Duramax Head Gasket Replacement [Archive]

More Power

05-31-2021, 06:10

5/31/2021: Well, I'm into it. Pulled the truck into the cleaned-out garage yesterday, and began the dis-assembly. A lot of prep work had to be done before hand...

In the meantime... Update 8/7/2024...

https://www.youtube.com/watch?v=20JXJx-luNQ

This video is an introduction to Duramax 6600 diesel service - and is the first in a series that will eventually show how to do what's necessary to complete a fuel injector replacement, cylinder head gasket replacement, water pump replacement and much more. But first, let's talk about what tools, tips and supplies you'll need to do the work in the best way possible.

If you're interested in learning more about Duramax 6600 service and repair, then the introductory YouTube video shown here would be the best place to begin. We've helped thousands of Duramax owners with their own service work through the years. We can help you too.

Can't wait for the video series to be complete? Would you rather have a complete printed Duramax Diesel Service Guide now?
See: https://www.thedieselpage.com/duramaxdieselserviceguide.htm

Our YouTube channel is new, but its growth will help us to provide so much more - at no cost to you.

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Subscribing to TDP's bulletin board forum and our YouTube channel will ensure you don't miss any new videos. As always, your input, suggestions and advice are all important.

Lastly... The most recent video in this Service Guide video series has been posted near the end of this thread titled: No Fail - LB7 Duramax 6600 Injector Replacement (https://www.thedieselpageforums.com/tdpforum/showthread.php?46717-Duramax-Head-Gasket-Replacement&p=337032#post337032). Have a look!

Robyn

05-31-2021, 07:26

Anxiously await lottssa pics

Yukon6.2

05-31-2021, 10:55

Watching as well i think the same job is in my future on my 2001 Tow truck.
Getting a hard rad hose,and losing fluid,smoke on starts

a5150nut

05-31-2021, 12:21

Will there be Pop Corn provided?

Robyn

05-31-2021, 17:39

BYOPC....;)
Shop towels advised.....Coveralls mandatory dress code.....yeah buddy

More Power

06-01-2021, 07:28

I'm looking at 2 possibilities, as of right now, for why I was seeing excessive pressure in the cooling system. By the way... there are patches of soot visible inside the coolant surge tank, which is a dead give-away.

The 2 possibilities...

#1- The No. 2 injector failed at about 120,000 miles (I identified it as having a way out of range fuel rate), which produced a "chugging" while the engine idled, like at a stoplight. I suspect that may have stressed the head gasket surrounding that cylinder - maybe.

#2- The excessive pressure in the cooling system was identified not long after an injector replacement (see #1). My GM Duramax mechanic/enthusiast friend seems to think the problem will be identified as a cup seal leak. He's seen enough LB7 cup seal leaks in his day (that follow an injector replacement) that he developed his own procedure to prevent them from happening. If my truck's problem is due to a cup seal... then it may have been a byproduct of risky/lazy injector replacement (meaning it was an independent shop's fault... :mad:). Unfortunately, without taking it apart there's no way to tell if the excessive pressure is due to a bad gasket or a cup seal leak.

Another "by the way".... according to my mechanic buddy, the design of the Duramax head gasket produces a more likely problem at the #2 and #7 cylinder. If the head gasket were to fail... and that's not injector or cup related, the problem always winds up being associated with #2 or #7.

Have a look near the end of the following story on water pump replacement to learn more about head gasket failures*.... (LB7 cup seal problems). https://www.thedieselpage.com/duramax/duramaxwaterpump.htm

Robyn

06-01-2021, 16:58

Dig into it Jim
Gonna be interesting to see what ya find...

More Power

06-02-2021, 08:32

Here's a shot of the engine bay as it exists this morning (June 2, 2021). Getting closer... I need to unbolt the exhaust up-pipe from the exhaust manifold and remove the steel fuel lines. There's still a fair amount of electrical and plumbing to get the left side clear enough to look like this side.

I know there's a grounding strap on the back of the driver's side head (left side) that'll need to be unbolted. And, I think I just need to remove the three bolts at the bottom of each exhaust up-pipe to then free the heads... If I'm missing something, let me know. The book says the turbo needs to be removed to do a head R&R, but it looks like I can get the intake Y-pipe unbolted without removing the turbo. Just need to remove the turbo compressor inlet elbow to allow access to the intake bolts... I think.

Getting the electrical connectors disconnected up to this point took quite some time... There are many different types used here, and each has its own enigmatic snap-lock design (plus needing to be very careful due to 20 year old hardened/fragile plastic). You can see the soot in the plastic coolant surge tank...

https://www.thedieselpage.com/images/engine-bay01c.jpg

Kennedy

06-02-2021, 08:52

Robyn

06-02-2021, 09:39

I am with John

I would clear off the crap on top and then yank the engine out.

One little issue in a hard to reach spot can lead to a redo.....and that stuff sucks.

Take your time and yanking the engine will not be all that bad.

THEN... you can walk up and get quite intimate with the old girl....
And if there are any other things that show up....they can be dealt with easily.

PLUS....While the engine is out...you can muck out the engine bay and make it all spiffy.....

More Power

06-02-2021, 09:48

We've done them in chassis I believe one time. Then started removing engine from chassis altogether. Easier to work on this way. Most lift the cab, and we always thought about it, but the risk of doing any paint and body damage...

Use a 10 mm ujoint socket for the turbo inlet bolts. The ones that I have are Snap on and have a very shallow socket.

ANY signs of rust on the injector inlet bowls or supply lines I would replace with new, in fact a set of SAC 00 injectors with new lines would be mandatory on my list. Hazing at idle shortly down the road will tend to break your spirit and all LB7 VCO seem sto do this. Some sooner than others.

Thanks John.

The injectors in the engine now only have about 20k on them. I had planned on having them cleaned/checked/tested before they went back in. But, I hear you on the "spirit" point... It's a lot of work to complete a project like this, to then have an injector issue soon/right after... I'll think about it...

Do you agree that the bottom 3 bolts on the exhaust up-pipes will free the heads from the exhaust system? Or, are there any bolts on the back side of the heads that secure the heat shields?

The GM mechanic I mentioned earlier told me that they lift the cabs too, but I was against it for of a variety of reasons - including damage to the cab, and then having persistent gremlins move in (with electrical, A/C, brakes, Allison shift cable, steering shaft, etc.). He then said his next option would be to pull the engine. Working mostly alone and without a vehicle lift, I pulled each inner fender wheelhouse and front tire/wheels, then lowered the front of the truck about 5-6 inches onto jackstands. Using plywood, I then made a 6" high x 24" wide x 48" long platform to stand on while leaning over the rad area. I can still pull the engine if it comes to that.

More Power

06-03-2021, 15:01

Had to buy a few more tools... i.e. a short 1/2" drive 12mm 12-point socket, a 10" long 12mm 12-point box wrench (need the leverage), 19mm flare nut wrench for the steel injector hard lines (although I used a 3/4" crow's foot, which worked perfectly), a set of 1/4", 3/8" and 1/2" drive adapters for my battery powered drill/driver, a set of metric Allen ball drivers and a couple misc tools to help out. Then, I removed the passenger side exhaust manifold and glow plugs. Up next is the driver's side exhaust manifold/glow plugs. I've heard that it's easier for one person to get a head up and out of the engine bay if the exhaust manifold has been removed. Gotta be careful not to ding the aluminum deck surface of the head.

Advice from John and others I trust say the ARP studs are the better choice over the factory TTY head bolts. So... we'll go with that. More later...

Update: 5/30/2024

https://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=7629&d=1717096528

This image shows the worst area of the worst head gasket. This is the block deck side of cylinder #2 (front-most cylinder on the driver's side). To recap, the engine had 140,000 miles on it at the time of the head gasket replacement in June of 2021, and the truck had endured 20 Montana winters. The head gasket leak began in about 2016 with the truck having ~120,000 miles on the odometer. I'd been living with this chronic, though slight, cooling system over-pressure problem for about 5 years. This made the truck unusable for anything but local driving all during that time.

It's hard to know how many cold starts occurred from when the truck was new to June of 2021, but it is my contention that over 15-20 years, the coefficient of expansion differential between the aluminum heads and the cast-iron block may have produced some scrubbing that contributed to a reduction in sealing ability of the head gasket, This eventually resulted in a combustion pressure leak into the cooling system -which was the reason for this head gasket replacement... The head gaskets simply wore out. This is why the service manual calls for a final finish of 600-grit wet/dry paper used with a light oil. A rougher texture on the deck surfaces, using some other method, will shorten the life of these gaskets.

I've had nearly 3 years to think about all this as of May 2024, and that's still my best guess as to the cause of the head gasket failure discussed here. There has been no excessive pressure buildup in the cooling system since the service. It's such a relief having the truck reliable again... ;) TDP

We need your help too! Would you like to share this thread with others or help us get the word out about Duramax head gasket service? I hope so. Copy the following link and paste it into another forum post, text message, DM, email or social media site:

thedieselpageforums.com/tdpforum/showthread.php?46717 (http://www.thedieselpageforums.com/tdpforum/showthread.php?46717)

Thank you!

Robyn

06-03-2021, 17:09

Hang in there Jim......It will get easier the more stuff ya get off of the beast.....

Dr. Lee

06-06-2021, 10:35

This will give you a real workout, Jim. If I were closer to Montana I would be there to help you. If you do pull the engine out, you can do everything necessary to have it run another 20 years, and by then you might be ready for something different, like the diesel El Camino you have always wanted.

DmaxMaverick

06-07-2021, 12:23

The head and gasket look to be unremarkable. Really good for a 20 year old, actually. Just an observation.

80/120 grit on an aluminum head? I can see Scotch-Brite or 600 as reasonable, and what I might use. Anyone who'd suggest 80 grit gets no more of my attention. I doubt you could fix that with a mill.

convert2diesel

06-07-2021, 13:21

When re-doing the heads on a 6 liter gasser (aluminum heads) the FSM wants the surface to be "R15". When I got them back from the machine shop, you could almost see your face in the surface. In other words, check the FSM for surface requirements. Just a thought.

Bill

DmaxMaverick

06-07-2021, 14:44

According to (the latest bulletin regarding head/gasket prep and install):

Bulletin No.: 06-06-01-006C

Date: October 30, 2009

Subject: Information on 6.6L LBZ, LB7, LLY Duramax(R) Diesel Engine Cylinder Head Gasket Design Change - New Head Gasket Part Numbers and Head Bolt Torque Specifications

Models:
2001-2006 Chevrolet Silverado
2003-2006 Chevrolet Kodiak C4500/5500 Series
2006 Chevrolet Express
2001-2006 GMC Sierra
2003-2006 GMC TopKick C4500/5500 Series
2006 GMC Savana
with 6.6L Duramax(R) Diesel Engine (VINs D, 1, 2 - RPOs LBZ, LB7, LLY)

[snip]

Special Cleaning Requirements
For 2001-2006 vehicles produced with the first generation head gasket, special attention must be given to the cleaning of the engine block and cylinder head surfaces when servicing with a second generation gasket. The crimped areas (1) on the first generation gasket may, over time, allow corrosion buildup where they contact the block and cylinder head surfaces. The second generation gasket has raised ribs that seal at these crimped areas (1). A special cleaning procedure is required to ensure proper sealing.

Cleaning Procedure

1.
Remove the old head gasket using service manual procedures. Save the gasket for reference until the repair is completed.

2.
Place clean rags in the cylinder bores and pushrod openings in order to keep out debris.

3.
Use the J-28410 or equivalent to carefully clean the gasket sealing surface of large sealing or corrosion matter. When scraping, take care not to scratch or gouge the metal surfaces. Do not push the debris into oil, coolant, and combustion openings or bolt holes.

4.
Inspect the gasket sealing surfaces for corrosion, especially in the areas that were in contact with the crimped tabs of the first generation head gasket. If corrosion is present, continue with the rest of the steps in this procedure for proper cleaning. If the sealing surface is sufficiently clean and smooth, use the revised torque specification listed towards the end of this bulletin and continue with published service manual procedures to complete the repair.

5.
For surfaces that have corrosion or pitting, wrap a piece of flat steel (4"x 2" or larger) with 600 grit wet grade sand paper. Using Moisture Displacing Lubricant, P/N 88862629 (in Canada, use 89020803) or equivalent, wet sand the block surface to remove any remaining gasket material or corrosion. Do not use any paper coarser than 600 grit.
Notice

-
Do not use any power type sanding devices.

-
Do not use a wire brush or wheel to clean gasket surfaces.

-
Do not use chemical cleaning agents on gasket surfaces.

6.
Take care to keep the sanding block parallel to the block surface and evenly sand the sealing surface. Some areas of corrosion will still show a stain. Do not attempt to wet sand these areas down to a shiny metal surface.

7.
Change the sanding paper when it becomes clogged. Carefully and frequently wipe the surface, using a clean cloth each time, to prevent sanding debris from building up and contaminating the oil and coolant cavities.

8.
Clean the bolt threads and holes and remove the rags from the bore cavities and pushrod openings.

9.
Repeat the above cleaning procedure on the cylinder head gasket surface.

10.
Clean the engine block and cylinder head gasket surfaces with Brake Parts Cleaner, P/N 88862650 (in Canada, use 88901247) or equivalent, to remove any traces of oil or debris.

11.
Using the revised head bolt torque specification below, reassemble the engine with NEW M12 cylinder head bolts according to service manual procedures.

Also:

Bulletin No.: 07-06-01-009A
Date: November 02, 2009

Addresses head gasket thickness identification, Gen 1 crimped gaskets vs. Gen 2 riveted gaskets, and revised head bolt torque and angle procedure. DO NOT use the original Gen 1 head bolt torque procedure with Gen 2 riveted gaskets. Definitely worth a read.

RTFM (note to self)

Robyn

06-07-2021, 16:50

I can't imagine using 80 grit.....omg...

DmaxMaverick

06-08-2021, 08:57

Thanks Greg... does the info you have list the new torque specs - i.e. "Using the revised head bolt torque specification below..."

It does, in the 06-06-01-006C bulletin. I'll send the PDF to your email. The bolt torque pattern isn't specified, but it's the same as original.

More Power

06-08-2021, 12:52

Thanks Greg,
The original gaskets identified in the TSB with arrows ("showing the crimped construction") did produce a buildup of rust on the block deck at each of those locations pointed to. Those small areas of rust build-up need to be removed, probably by first carefully scraping them down to block deck level.

Once I'm close to the end I'll make a list of the special and common tools that were either necessary or made the job easier. I'll also have some tips that'll make it easier, safer and produce a better result. I'd loan them all to you, but I have yet another LB7 to do once this one is back on the road. I'm sure it's punishment for something... ;)

DmaxMaverick

06-08-2021, 12:54

....I'm sure it's punishment for something... ;)

If that's the worse karma thrown at you, I'd not complain too much.

More Power

06-08-2021, 13:13

As a "by the way", I couldn't resist watching one really short Youtube that was entitled "Remove the Duramax Damper Bolt in 2 Seconds".

He used a 36mm socket and a ~24" 1/2" breaker bar, with the bar wedged behind the alternator pulley, held in place using bungie straps. Then, he got into the driver's seat and bumped the ignition key. The engine loosened the bolt.

This seems more like a "here hold my beer and watch this moment", especially with a naked rear surface of the radiator in the video only inches away. I'd be wary of the engine starting with just a bump of the key.... then the loose tools would wreck the radiator, throw the wrench into a fender, then the windshield, then across the parking lot into your wife's car... :(

DmaxMaverick

06-08-2021, 13:50

That's how I get 'em loose, sort of. Radiator protected with plywood, 1" breaker bar, strapped down, extended to a wood block on the ground, and driver fuse pulled (no fuel). I broke a 1/2" breaker the first time, so up to the 1". Just a bump of the starter is all it takes. You could "jump" the starter solenoid, just the same, but it's easier to pull the fuse and bump the key. At the same time, if an LB7 started at the bump of the key, it's be the first time I've ever heard (they all take at least 2-4 seconds of cranking, in my experience). I made a tool for tightening, that fits into the holes in the balancer, and braces against the socket on the bolt. The alternative is removing the starter and locking the ring gear with a special tool (that I don't have, but probably should). Ask me how I get the front brake bracket bolts loose, unless the above method makes you queasy.

More Power

06-08-2021, 15:23

I bought these flex-plate/flywheel locks some time ago. One of these was designed for the Allison (not sure which one right now, the other for the ZF equipped trucks), which is inserted into where a thin steel inspection plate near the driver's side lower section of the Allison bell-housing can be pulled back to expose the teeth on the flex-plate. I suppose it's used to allow removing the transmission (by first removing the 6 torque converter bolts - through the starter opening) as well as help with removing the damper bolt. They were priced pretty cheaply. Just gotta make real sure it's removed before trying to start the engine... :eek:... Maybe tape a big note to the steering wheel...

https://www.thedieselpage.com/images/Duramax-head-gasket/Flywheel locksc.jpg

DmaxMaverick

06-08-2021, 15:36

Robyn

06-09-2021, 05:11

Thanks Jim....I will check out the Video.

Keeping all the crud out of the engines innards is a challenge to say the least.....

Rags and such can help.....but SANDING grit is nearly impossible to keep out of the cylinders and other openings.

The stunts that some so called mechanics pull makes me cringe.....

More Power

06-09-2021, 07:21

That's good to know. The last Kent-Moore tool I saw for that bolted in place of the starter, and the manual called for removing the starter. Is that an updated Kent-Moore tool, or an aftermarket better idea? Where did you source it, if you don't mind me asking?

https://www.thedieselpage.com/images/Duramax-head-gasket/Lisle-02.jpg

Kennedy may sell that part. If not,

Go here: https://duckduckgo.com/?q=duramax+flexplate+locking+tool&atb=v265-6__&ia=web

By the way, that is a 3/4" drive 36mm 12-point impact socket for the damper bolt. I've seen the locks sold separately for less. The above link should help.

More Power

06-10-2021, 08:34

After reading the TSB about how to prepare the head/block deck surfaces, I pondered what I would use for a sanding block...

"For surfaces that have corrosion or pitting, wrap a piece of flat steel (4"x 2" or larger) with 600 grit wet grade sand paper."

I didn't have anything that would qualify as precision flat, so I contacted my fabrication guy. Here's what he was able to produce on his milling machine for me - a flat 1/2" x 3" x 4" steel block.

https://www.thedieselpage.com/images/Duramax-head-gasket/Sanding Block-sm.jpg

This was made from 1/2" chromium steel plate of the type used for silhouette targets.

I watched a YT video recently that showed what another guy used... a 6" long piece of angle-iron. That could work if he spent some time with sandpaper and a flat surface to sand it smooth and flat. He may have...

DmaxMaverick

06-10-2021, 22:54

While I wouldn't call that a smoking gun, it's an indication of something. What's the head and deck look like at that location?

Robyn

06-11-2021, 06:33

The leak required to pressurize the cooling system is minimal...
The area on that fire ring is mighty close to the coolant passage.....

The condition of that fire ring is pretty sketchy.....

Sure looks like a good possibility to me...

Getting the heads and decks cleaned up well with the "Sanding block" should give you a good idea of what you are dealing with.....

I would do a good wipe down of the cylinders and look for anything hinky ....as in strange stains or discoloration ......

Just to be sure and cover the bases...

DmaxMaverick

06-11-2021, 11:47

More Power

06-11-2021, 12:40

Is the firing ring impression consistent all the way around, and consistent with other cylinders? If they are all typical, and the manual and other technical sources don't hint at milling, would they all consider that condition normal, and not need a correction? I'm wondering if it's a product of aluminum vs. steel under high loading/torque or perhaps 20 years of high, sustained pressure. Or, is it a condition involving erosion or corrosion? I suppose it could be calculated, considering the force PSI, effected area, and hardness of the aluminum, exactly how much of an impression it should have. Even if you had them milled, would torquing a new gasket result in the same? If milled, would you be repeating exactly what you're seeing now? I don't know of anyone who's immediately removed a freshly torqued aluminum head for a look. I know it sounds skeptical (I am, a little), but mostly just thinking out loud. This is essentially a new territory for me, and something I'll likely be visiting in the near future. I've done dozens of aluminum head jobs, but those were almost entirely smaller engines, V6's, I4's, and boxers in compact/mid cars. I did assist with an LS V8, but wasn't present for the whole job and don't recall anything remarkable. Fire ring impressions were somewhat, albeit much less pronounced, typical, and often were at least minimally, still present after machining. It never became an issue, after the fact.

The fire ring impression is not entirely uniform all the way around the pictured head deck - or for any particular cylinder for that matter, but the head decks for the center cyls appear to be more lightly affected while the most effect can be found on the outside of the end cyls... and, none of them are really that bad, but everything is subjective and my inexperience with this makes my judgement a little rocky.

The guy I spoke with at the engine shop said it was due to "brinelling". But, he did say there was a time/mileage component to it, indicating that a 140K engine would likely need to have the heads milled while a 5-10K engine likely wouldn't.

You can see in the above image on the upper and lower left corners of the head where the small "crimped" areas on the head gasket had imprinted (brinelled) the aluminum. This is likely why GM redesigned the head gasket to include external rivets (outside the mating surface areas) in place of the crimping. Aside from a redesign of the gasket, GM also reduced the torque of the head bolts... Maybe because of the brinelling....

My guess is that a resurfaced head would brinell yet again, but would last another 20 years...

According to Wiki...

Brinelling is the permanent indentation of a hard surface. It is named after the Brinell scale of hardness, in which a small ball is pushed against a hard surface at a preset level of force, and the depth and diameter of the mark indicates the Brinell hardness of the surface. Brinelling is permanent plastic deformation of a surface, and usually occurs while two surfaces in contact are stationary (such as rolling elements and the raceway of a bearings) and the material yield strength has been exceeded. The brinelling is undesirable, as the parts often mate with other parts in very close proximity. The very small indentations can quickly lead to improper operation, such as chattering or excess vibration, which in turn can accelerate other forms of wear, such as spalling and ultimately, failure of the bearing.

DmaxMaverick

06-15-2021, 11:54

That's purdy. Doesn't look like he used 60 grit paper and a 2x4.

Robyn

06-15-2021, 14:44

Loooking great

convert2diesel

06-16-2021, 06:37

More Power

06-18-2021, 05:59

Thats what my 6.0 heads looked like when I got them back from the machine shop. Forced me to do a much better job on the block side. Sort of makes you want to polish the decks. Would polishing compound work on cast iron?

Bill

I know... I feel the same way. However, the service bulletin says not to attempt to block sand the surfaces on either the heads or block decks to produce all shiny new metal. "Staining", they say is perfectly OK to remain, just not old gasket remnants or corrosion (rust) above the deck surface. The flat steel block ensures that the high spots will be removed, and besides, 600 grit paper wouldn't allow you to remove all traces of everything anyway - on the cast iron - without the patience of the Saints. Gotta be careful on the heads though. A scraper, properly and carefully used, will get almost all of the old gasket material, carbon deposits, and most corrosion off. Where you'll spend the most time with the sanding block is on the rusty perimeter of the block decks. Can't take all the rust off, just take enough to produce a flat surface transition - run your finger across is. The rusty perimeter is outside the gasket edge anyway. Jim

Robyn

06-30-2021, 13:11

Good to hear that things are coming together....

When you going to build a fire in it ?????

More Power

07-02-2021, 06:21

I've got most of the coolant and fuel hoses/pipes connected... The electrical is upcoming. Won't get to work on it much today, but I suppose Monday/Tuesday will be close to when it'll be ready.

Robyn

07-02-2021, 06:30

SWEEEEEEEEEEEEEEEEEET.

Will be great to have it all back together and purrrrrring away again.....

More Power

07-05-2021, 11:24

Nearly complete. Trying to figure out which wire goes where... ;)

https://www.thedieselpage.com/images/Duramax-head-gasket/nearly-complete.jpg

convert2diesel

07-05-2021, 19:45

Thats what they sell masking tape and sharpies for.

Looking good.

Bill

Robyn

07-06-2021, 05:23

Yup.......Been there done that trip.......

Butttttttttttttttt.....Most electrical connectors are item/location specific and will only go one place.

More Power

07-06-2021, 13:28

It lives!

Started it for the first time this morning. Checked for leaks after the first two non-firing cranking sessions. Found a pretty significant fuel leak on the forward end of the right fuel rail. Seems I forgot to tighten the fuel line nut (pointed to in photo below) that feeds the rail... :eek: Only needed to remove the alternator and AC compressor (to get the alt off). Luckily, I could get my 3/4" claw-foot and an extension to work with my tq wrench to reach under the wiring bundle in that area. That fitting is tq'ed to 30 ft-lbs. I think it's leak free now.

https://www.thedieselpage.com/images/Duramax-head-gasket/rail-leak.jpg

No abnormal pressure buildup in the cooling system, which is why all this was done in the first place. Starts and runs really well. Drove it a few miles to burp the cooling system. No SES lamp or trouble codes. Sounds a little different than before.

When re-installing all of the coolant-related parts on top of the engine, I noticed that most of the gaskets and o-rings had been leaking/oozing a little over time. I suspect that the cooling system over-pressure the engine had been having over a long time worked on the gaskets/o-rings too. I replaced all of those gaskets/seals/o-rings and installed new thermostats. The rubber gaskets on the t-stats had been leaking a little too, and they weren't properly regulating engine temperature - ran a little on the cool side.

Once the engine cools overnight, I'll change the engine oil and filter, then re-install the wheelhouse liners. Hopefully that's it. "Only" about 80 actual hours start to finish, not counting the ~400 mile round trip to get the heads resurfaced. No broken parts, no lost (or "left over") bolts/hardware, no broken electrical connectors, no scratches on the truck, just a few scraped knuckles, got a better result for far less money... New SAC00 injectors, new updated "C" grade head gaskets, new injector hard lines and ARP studs, plus some new tools (including two small torque wrenches) for something over $4K. I'll have a more accurate accounting when I go through the pile of receipts. This job would have cost $10k if you'd hired it done...

More Power

07-06-2021, 14:05

Thats what they sell masking tape and sharpies for.

Looking good.

Bill

Thanks Bill,

Mostly kidding about the electrical connector puzzle...

Although, it took me a while to figure out one connector on the driver's side. The answer came when I remembered that it was for the oil pressure sender connection to the engine harness. On the passenger side, I had this important-looking connector on the harness that had no mate on the engine, then I remembered it was for the MAF sensor on the airbox (which was sitting on the parts table). And lastly, the glow plug controller module has 4 connections. I didn't do a good job documenting the wiring, so I had to dig through my photo archive to find a photo of a wired GPCM. The best photo I had only showed a part of the module, but after some head scratching it was enough. Every other electrical connector was, as Robyn said, pretty much self evident - there are so many of them...

Robyn

07-07-2021, 05:17

Good to hear that things went reasonably well....

The first start up after a major tear down is always tedious and usually bends the nerves a bit.
Looking forward to hearing the results of the road test.....

DieselDavy

07-08-2021, 18:13

Congratulations Jim!
Glad to see you got it up and running again. 80 hours isn't so bad for a guy who doesn't do it for a living....
Way to go!
Dave

More Power

07-09-2021, 07:37

Congratulations Jim!
Glad to see you got it up and running again. 80 hours isn't so bad for a guy who doesn't do it for a living....
Way to go!
Dave

Thanks Dave. Not as young as I used to be either... 36 stud nuts each torqued in sequence at 30, 42, 84 and 125 ft-lbs while sitting on the rad core support was a high point... ;)

More Power

07-09-2021, 15:55

Deja Vu - photo taken just 10 minutes ago... It begins again...

https://www.thedieselpage.com/images/Duramax-head-gasket/Deja.jpg

DmaxMaverick

07-09-2021, 21:03

Take 2?

More Power

07-12-2021, 06:38

Take 2?

There was once an "incident" with nitrous... producing a nagging cooling system overpressure. I suspect a couple of the head bolts may have yielded a bit. The first head will come off later today or tomorrow, depending on how much time I get to work on it. Working on the engine is generally easier in Lil Red than it was in the GMC - the truck is lower, and there's more room in certain areas (rear of the driver's side head). Plus Lil Red has a lot fewer miles (about 10k), has never been apart before and has never seen road de-icer.

Dr. Lee

07-12-2021, 18:49

There was once an "incident" with nitrous... producing a nagging cooling system overpressure, that I suspect may have caused a couple head bolts to yield a bit. The first head will come off later today or tomorrow, depending on how much time I get to work on it. Working on the engine is generally easier in Lil Red than it was in the GMC - the truck is lower, and there's more room in certain areas (rear of the driver's side head). Plus Lil Red has a lot fewer miles (about 10k), has never been apart before and has never seen road de-icer.

I was a little more cautious with the nitrous and propane in my 6.5L. You gotta keep Lil Red in top-notch shape, you have LOTS of sweat equity and brain-power equity invested in her.

Robyn

07-13-2021, 15:25

Sounds good.....

Be interesting to see what actually happened...and why the pressure issue....

More Power

07-14-2021, 08:35

Sounds good.....

Be interesting to see what actually happened...and why the pressure issue....

Robyn,

My thoughts about the causes of over-pressure problems are evolving. My thinking at the present time include:

1- The head gaskets simply wear out over years of use due to the friction caused by differences in the coefficient of expansion rates between aluminum and cast-iron. I suspect there's a direct correlation between thermal cycles and head gasket life (in the case of my GMC - 15+ years and 140,000 miles), at least with the original crimped head gaskets.

2- Head bolt(s) yield for whatever reason (especially when beyond stock power/boost levels), which reduces the clamping load - resulting in combustion pressure leaks. With Lil Red, there's a direct connection in time between a nitrous backfire at the track and the first appearance of the cooling system overpressure... What's interesting is that GM reduced the head bolt torque angle settings (reduced the torque) of the same TTY head bolts when installing the newest riveted head gaskets. Perhaps the earlier/original crimped tabs were interfering with head bolt clamping force.

3- The original head gaskets used crimped tabs at various places around the perimeter of each gasket. These crimped tabs were what kept the multi-layer gaskets locked together. The tabs are thicker than the surrounding gasket and are located between the head/block surfaces - making it harder for the head bolts to effectively clamp/seal the gasket. You can see what effect this has on the gasket and where most of the questionable sealing occurs. The new riveted design has the riveted areas outside the head/block mating surfaces, so they don't interfere with the effectiveness of the head bolts to maintain clamping load over time.

More Power

07-14-2021, 12:27

I watched an ARP video a while back where they discussed the "elastic" clamping load supplied by properly installed and torqued Series-2000 head studs produced for the Duramax. I like it that the ~$650 head studs have some elasticity designed-in.

However, we know that GM is still using TTY bolts in the newest L5P Duramax, which is rated for 445 hp / 910 lb-ft - and rated for up to a 35,000-lb GCVWR.

I interviewed the "Duramax Power Tour" team in 2000, who drove an LB7 equipped 3500-series truck towing a 20,000-lb event trailer. I rode in that truck as they wailed on it, on the I-90 continental divide pass just east of Butte, Montana. I asked them if they drove it like that all the time. I was told yes... They put in excess of 20,000 miles on that truck - hammer down all the time. I can also point to a 750,000-mile LLY Duramax used to commercial tow RV trailers all over North America, that I wrote about a few years ago. GM could acquire head studs equal to those offered by ARP (maybe even contract with them to provide) if they felt it was necessary.

I have a couple of debate points about studs that are hard to answer and difficult to challenge. 1- The aftermarket pushes anything that they can sell - ("while you're in there") type of stuff, including head studs. 2- Studs are simply easier to install than TTY bolts. You must mark the heads of each TTY bolt during the two angle tightening sequences or you'll mess up the installation. With studs, you only use a torque wrench. If you forget one or get out of sequence, it's really easy to check what the torque is for that stud. Personally, I think this is why many vendors/mechanics push studs (sell more expensive stuff and they are easier to install). Otherwise, they would/could point to actual durability tests involving direct comparisons between engines using head studs and TTY bolts (fleets would be the best source of information. Second best would be an accumulation of real-world reports from actual owners - like the story I did on the 751k mile LLY Duramax). For most, these head gaskets will wear out long before any real comparison can be done on the veracity of claims otherwise.

I plan to measure the actual torque applied to these TTY bolts after completing the 2-step torque angle installation. We know that GM/DMAX reduced the final TTY head bolt torque angle setting when they introduced the new updated head gasket in 2007. I suspect this was to reduce the Brinelling of the head gasket fire-ring onto the aluminum heads. Knowing what the torque is for current ARP studs (125 ft-lbs), it'll be interesting to learn what the actual torque value is for the installed TTY bolts. The current TTY installation takes the TTY bolts from a static torque installation setting of 59 ft-lbs then adds two separate 60 degree rotations for a total 120 degrees. The original Duramax TTY bolts saw a 150 degree sweep after the 59 lb-ft static tq setting.

Robyn

07-14-2021, 17:58

I agree 100% on the TTY BOLTS.....A cheap easy fix instead of doing it the right way..

You drive the rig with great care and NOT ...HAMMER DOWN .....The stock stuff will work.....

Take it into the ozones a couple times.....Maybe it will survive....maybe not......

A bolt that is already into it's elastic mode and then hit hard......all bets are off.

TTY BOLTS are more like taffy.......

A bolt that can stretch a little and come back will be far better than one that is into the"GOOOY PHASE" and then the extra hit simply stretches the bolts out waaaaay too far......."The bolts you found with less breakaway tension.

I have found the same mentality with the big snow cat.....do it cheap and dirty.....Yeah...good for a while...but when it fails ...things get ugly..quick.....

Are you going with studs on "Li'l Red" ?????

Robyn

07-14-2021, 18:04

More Power

07-15-2021, 07:51

A six and a half with REASONABLE power levels will do fine with TTY bolts.

Try shoving big boost and a buttload of fuel into a 6-1/2 and it will suffer....

I tried a set of MLS gaskets on a 6.5.....NOT ENOUGH HEAD BOLTS IF USING TTY..

ARP studs may have worked better.......

The factory stuff is always right on the ragged edge.....You always need more when you plan on flogging it hard.....

If money is no object, we would all live life differently and make different decisions regarding diesel engine service. Fact is, the ARP head studs are $650 and the factory TTY bolts are about $100.

Take an old truck to a diesel shop or dealership, and ask them to install a new head gasket kit ($400), ARP head studs ($650), new injectors ($2400), new injector hard lines ($650), new water pump ($125), new hoses and an endless list of "as long as we're in there" stuff, and of course at least $5k in labor - and you've made a bad decision regarding financial common sense - i.e. spending $10k+ on a truck that in even perfect condition is still only worth 10K. When faced with that reality, most thinkers will crush/part-out the truck and not spend a dime on it... We didn't even talk about brakes, ball joints, steering components, drivelines, tires, rust... and on and on and on...

Meanwhile, our performance 6.5TD Project ran without a problem to 300,000 miles in 7 years using TTY head bolts (till we sold it), and my 2001 GMC ran to 140,000 miles using TTY head bolts - even with the poorly designed factory crimped-style head gaskets. I get where the ARP stud advocates are coming from. This is partly why I installed ARP studs in my own 2001 GMC LB7 head gasket repair. I spent extra on this truck only because I did the work (and because I needed to install the studs so I could photograph it and eventually write about it). It's just that at some point, all those faced with a significant repair on an older truck need to make a decision... Do you crush the truck or do what is necessary to save it without compromising basic service and dependability while not violating financial common sense? As part of an overall budget strategy, I think the lower cost TTY head bolts fit into that paradigm. And... Lil Red is getting TTY bolts.

What would mean most to me regarding this studs/bolts debate is to study the actual service histories comparing engines built with studs/bolts along with a description of how the trucks were used, and then be able to discern some sort of recommendation from that. Right now, the stud advocates "say" they are better... We can read about tensile strength and a wide range of engineering theory, but what's that really mean in the real world to average truck owners?

Robyn

07-15-2021, 12:58

Pretty much spot on..
Trying to do a "Budget" rebuild any more is a real challenge.

I am trying to build a 406 Small block Chevy for the snow cat....

Used Vortec heads in great shape (Zero cash outlay....Sold the short block to recover the total cost)
400 block $150 plus $350 for machine work
Pistons....New ebay score for $135
Good used stock crank.....$125
Still need the cam/lifters
Timing gear/chain
Gaskets
Oil pump
Fuel pump
Push rods
Have new high capacity pan $175
Flex plate

And on it goes.
Have a fresh carburetor $127
New exhaust manifolds $175 pair

Intake manifold for Vortec heads to fit 4 barrel carb.....$100 plus

No matter what it is....even when you do all the wrenching yourself.....$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

Adds up quick

56pan

07-15-2021, 17:04

"new injectors ($2400)" Are you writing about a 6.5 GM diesel? That's $300 per new injector?

More Power

07-16-2021, 06:44

"new injectors ($2400)" Are you writing about a 6.5 GM diesel? That's $300 per new injector?

That price is for remanufactured Duramax LB7 injectors. "New" as in replacing what was originally there. Prices vary between vendors. You can buy suspect stuff off eBay for less or spend a lot more for newly manufactured Bosch injectors. The $2400 price is for reman from Kennedy. Injector prices for newer model Duramax engines are more.

I had hoped back more than 15 years ago that injector prices would fall for the older model Duramax. I knew that as the truck's book value dropped, a critical point would eventually be reached where the cost to repair exceeded the "drop dead" percentage of 50% of vehicle value.

There is light though... I'll need to spend some time investigating, but it is possible to do what was unthinkable just a few years ago and replace the wear items in these injectors using only basic tools and skills. This, I believe, will become a big factor in saving the older trucks.

Robyn

07-16-2021, 06:59

DmaxMaverick

07-16-2021, 10:32

With a basic "Pop" tester you can check the pop pressure and observe the spray pattern.

Not quite as good as the tooling the big boys have....but you can get the job done.

Replace the nozzles and a few other small parts.... then shim the springs to get the pop pressure right.

I have done a few sets of "Squirts" for the 6.2/6.5 and other than the time to fool with them....They were fine......

I can't imagine the units for the DMAX being any tougher to do...

The LB7 squirts from what I have read were basically flawed from the get go and tend to be very fussy about any dirt in the fuel......

Be fun to rip into a set and give it a go.....

In theory.

But, it isn't that simple. I'm not too optimistic. Parts can be replaced, but that's about where it ends for the consumer. Capable test equipment would be necessary, as well as tools and a clean environment. The parts are relatively inexpensive and available, and not too difficult to replace, which creates a difficulty (at least for me) in seeing where the replacement cost of reman's comes from. I suspect they charge what they do, simply because they can. Bosch factory new and remans are costly, and non-Bosch rebuilders base their pricing on the Bosch list price. The actual cost of rebuilding these things is MUCH less than what they sell for. The profit margin is ridiculous, at more than 300%. I've researched it, and that's the most generous figure I can come up with. The parts, tools, labor and time just do not add up. For the cost of 2 or 3 retail injector sets, a shop can fully equip a station capable of quality full rebuilds, and a full set can be rebuilt and tested in a couple hours or less. Of course, it isn't that simple, but it certainly is not 300-500% more complicated. The same argument can be made of 6.2 and 6.5 injector pumps.

The LB7 injectors can see up to 23K PSI (later models are significantly higher), and idle at 4K+, and are fired by a solenoid, and will fire multiple times for each injection event (pilot injection, up to about 2700 RPM's). The volume of fuel is similar to the 6.5, but at the LB7 pressures, as with any hydraulic system, pressure and volume can be traded. Increased pressure decreases necessary component volume for the same fluid volume. Contamination becomes much more critical as the component parts become smaller. Herein lies the problem. The internal fuel volume components of the Duramax injectors must be very small, and meter fuel precisely. Known material failures aside (there have been a couple), that high pressure working against the tiny components results in erosion over time, which is also more rapid with greater fluid contamination. SAC nozzle injectors address much of the durability issue, but at a cost of less precision. Everything is a trade.

56pan

07-16-2021, 16:54

If money is no object, we would all live life differently and make different decisions regarding diesel engine service. Fact is, the ARP head studs are $650 and the factory TTY bolts are about $100.

Take an old truck to a diesel shop or dealership, and ask them to install a new head gasket kit ($400), ARP head studs ($650), new injectors ($2400), new injector hard lines ($650), new water pump ($125), new hoses and an endless list of "as long as we're in there" stuff, and of course at least $5k in labor - and you've made a bad decision regarding financial common sense - i.e. spending $10k+ on a truck that in even perfect condition is still only worth 10K. When faced with that reality, most thinkers will crush/part-out the truck and not spend a dime on it... We didn't even talk about brakes, ball joints, steering components, drivelines, tires, rust... and on and on and on...

Meanwhile, our performance 6.5TD Project ran without a problem to 300,000 miles in 7 years using TTY head bolts (till we sold it), and my 2001 GMC ran to 140,000 miles using TTY head bolts - even with the poorly designed factory crimped-style head gaskets. I get where the ARP stud advocates are coming from. I can actually read the engineering specs and understand the logic. This is partly why I installed ARP studs in my own 2001 GMC LB7 head gasket repair. I spent extra on this truck only because I did the work (and because I needed to say I did it, could photograph it and eventually write about it). It's just that at some point, people need to make a decision... Crush the truck or do what is necessary to save the truck without compromising basic service and dependability while not violating financial common sense. As part of an overall budget strategy, the lower cost TTY head bolts fit into that paradigm. Lil Red is getting TTY bolts.

What would mean most to me regarding this discussion about the value of studs/bolts is to study the actual service histories comparing engines built with studs/bolts along with a description of how the trucks were used, and then be able to discern some sort of recommendation from that. Right now, the stud advocates "say" they are better... We can read about tensile strength and a wide range of other stuff, but what's that mean in the real world to average truck owners?

My mistake. You had replied to a post from Robyn where she was writing about power levels in a 6.5 and I assumed your prices listed were for that engine.

More Power

07-16-2021, 20:20

...The parts are relatively inexpensive and available, and not too difficult to replace, which creates a difficulty (at least for me) in seeing where the replacement cost of reman's comes from...

That's the crux of what I'm talking about.

There are a lot of really good vendors out there - who have done a lot to push forward the service and performance of these diesels. But... it is a business, and some, unfortunately, are losing sight of the big picture. Unaware of what is happening, they are driving out both the older trucks and those new (read young) diesel owners who are the future of the market.

I've watched a lot of youtube videos recently about a range of Duramax repairs. Most of the videos are produced by 20-somethings to 30-somethings, some even doing the work (big jobs) in a car port... some in northern winter weather. Many are doing it because they can't afford a newer truck or can't afford to hire the work done. Everyone should realize that these are the new truck buyers a decade from now... unless the cost of repair parts drives them running and screaming away from diesels in general and the Duramax in particular. Generally, it's the kids who are buying many of the 10-20 year old trucks. GM has a stake in all this (creation of owner loyalty)... So does the aftermarket.

More Power

07-16-2021, 20:48

Something new! I pulled all 8 of the injector cups from the heads in Lil Red. Seven of the cup seating areas inside the heads looked pretty much identical to the following image.

https://www.thedieselpage.com/images/Duramax-head-gasket/Cup-Seal-Carbon-Track-02.jpg

I noticed while pulling the injector cups from this set of heads that they pulled quite a bit easier than they did from the heads in my GMC. It appears that there was very little sealant used on the cup tips when installed at the factory.

The following cup seat image shows what looks like carbon tracks due to a combustion pressure leak. The stainless steel cup had matching identical discoloration on it as well. Sorry for the slightly out of focus image. It's hard to get the camera to focus that deep into the head. I should have used a pre-set focal distance setting on my DSLR with an F11 or smaller aperture, but I didn't want to fiddle with it (end of a long day). So, I used my iPhone. This is the #8 cylinder, where the slightly loosened head bolts were found. Possibly the result of the nitrous...

https://www.thedieselpage.com/images/Duramax-head-gasket/Cup-Seal-Carbon-Track.jpg

DmaxMaverick

07-16-2021, 23:22

That's an absolute indication of....something. Likely, at least, a contributor to your pressurized coolant. What's the origin of the engine? I'm sure we discussed it before, but I don't recall.

Robyn

07-17-2021, 07:39

I agree on the small parts, high pressure and erosion..

At the pressures used in these systems it takes little abrasive to go to work on the metal.

When you consider the amount of time these parts are subjected to the abuse they take.....no wonder at all that they wear out.

Old school squirts like the 6.2/6.5 are pretty basic.....add the electronics to the mix and the issues get far more complicated.....A simple pop tester will not operate the Dmax injector.....

Working in a clean environment is an absolute.....
Follow factory protocols for the rebuild....No different than anything else we do when building an engine.
Can it be done at home in the garage.....yup.....I would not hesitate to go at it....just need specs on stuff is all.

I rebuilt several sets of Squirts for various 6.2/6.5
Are the ones done by many so called experts any better. ??????? Depends on the tech doing the job....Does he care about quality and is as finicky as we would be.....Big IF right there...

As far as pricing goes...

Here is an analogy of WHY THE COST.

I priced out new track belts for my cat project.
Go to snow cat supply company....1 belt 8" wide and 287-1/2" long $595 per belt

Go the the people who make the belting and spec it out $180 per belt for the same part..

BECAUSE THEY CAN CHARGE UP THE WAZOO.....and they will do so......

a5150nut

07-18-2021, 12:37

Robyn

07-18-2021, 14:52

Yeah buddy.

When I did the cat differential last summer/fall all the bearings had to be replaced (Water damaged)

Luckily the numbers were still readable.

The inner pinion bearing is a big roller bearing. And at $700 and change for the bad boy...../I went shopping.

Found a new one on ebay.....Located in New York state......$20 including shipping....

All the bearings came off ebay......all top brand names and exact part numbers..... averaged about $20 each.

16 big bearings in that sucker.....

If I had gone to the snow cat parts supplier.....I would have needed to mortgage the ranch...

Yes....prices are much variable......

More Power

07-19-2021, 07:26

That's an absolute indication of....something. Likely, at least, a contributor to your pressurized coolant. What's the origin of the engine? I'm sure we discussed it before, but I don't recall.

Here's what it looked like when I received it from GM... after it was uncrated. The Allison it came with had been used in a test vehicle. The engine looked assembly line new, but I thought it odd that the glow controller hot lead had been clipped off. I received this engine in the spring of 2002. I had assumed this was a new assembly line engine - a 2002 model year, but it was actually a 2001 model year CA emissions engine. The glow controller and glow wiring is the main difference between a CA engine and a 48-state Federal emissions engine.

https://www.thedieselpage.com/images/Duramax-head-gasket/Lil-Red-Original-Engine.jpg

It was at this point that I wish I'd clear-coated all of the aluminum components on the engine. So bright and shiny!

DmaxMaverick

07-21-2021, 10:00

More Power

07-21-2021, 10:19

I've always doweled several bolt holes and slowly lowered the head onto the block. Never gave it more thought past that. Is there something not obvious about the job, other than preventing a mishap that could damage the head? Your method looks very effective, though.

Not sure exactly what you mean by "doweled several bolt holes".

I watched a guy on youtube set a Duramax head onto a block (that was on an engine stand) after having already set all of the ARP studs in the block. Maybe he was a clod, but he had to get help after having floated the head over (and making contact with) all 18 studs and still not getting it on. I'd bet that head was scratched all over the deck. Even if done perfectly, I don't think that's possible in-frame with the cab on - certainly not on the driver's side. I know that the rear corner of the driver's side head bolt/stud must be inserted into the head before being lowered into place because of interference with the firewall.

My main motivation was about not damaging the head decks and gaskets. Cast iron heads are easier to deal with in this regard.

DmaxMaverick

07-21-2021, 12:56

"Doweled" as in, wooden dowels in the holes. I've used old head bolts with the heads cut off, as well (removed with a vice-grip). If clearance was an issue, short dowels. Wooden dowels got a screw in the end so they can be fished out with a magnet. If I had to use head bolts (never had to), I'd slot the ends so they can be turned with a screwdriver, then fished out with a magnet. I learned this from a retired Ford technician (50+ years) neighbor when I was a teen. He said he had a set for every engine and vehicle he worked on, and never just "tossed" a head on a block. "It's just too easy to do it right the first time." All of my first vehicles were basket cases (dirt cheap or free), so I got a lot of experience. I paid more on DMV fees and insurance than vehicles for many years.

More Power

07-23-2021, 08:06

I have both heads on, and the first two initial bolt torque settings applied. Next step is to complete the TTY torque angle settings (2 passes at 60 degrees each).

More Power

07-28-2021, 07:01

https://www.thedieselpage.com/images/Duramax-head-gasket/nearly-done.jpg

This is how it looked late yesterday. Nearly done! Maybe I'll attempt a restart later today.

Now I know why some mechanics like ARP studs... They are a lot easier to install. Took me about 2 hours to take all 36 bolts through 2 sequences, what with the setup for each torque angle setting, and wanting to do the best job I could... while in the truck. I watched the TTY head bolts installed at the DMAX plant in Morraine, Ohio back in 2001 - they are all installed at the same time by a machine... Took maybe 30 seconds for each bank. I was thinking of that day while fiddling with the angle card setup for each bolt.

arveetek

07-28-2021, 10:05

I watched the TTY head bolts installed at the DMAX plant in Morraine, Ohio back in 2001 - they are all installed at the same time by a machine... Took maybe 30 seconds for each bank. I was thinking of that day while fiddling with the angle card setup for each bolt.

I remember that! I was there for the plant tour as well, and I thought that was the coolest machine ever.

Casey

More Power

07-29-2021, 10:33

Completed the 1,254th step (somewhat hyperbolic) in the process late yesterday afternoon. I had spent some time priming the fuel system using the hand pumping plunger on the fuel filter housing while using both the bleeder screw and the fuel test Schrader port. The engine started on the second 15 second cranking cycle. Purrs like a kitten. There were no check engine light or leaks. I was extra careful to make sure every potential leak source was properly installed and tightened before moving on to the next step.

I shut it off, and spent some time looking everything over, then re-started the engine. Now, there was a service engine soon (SES) lamp. I shut it off, and looked under the hood for anything out of place. I found that the MAF electrical connector had become mostly unplugged. I straightened that out, which must have been due to not getting it latched completely, and the fact that I had to push and pull the air duct to get the new AFE air filter installed - all of which moved the MAF sensor around. However, getting the MAF re-plugged didn't turn off the SES. My Predator programmer won't communicate with this truck... it's married to my 2001 GMC, so I don't have a code to report. Does anyone know if a MAF code has to be cleared or does it go out on its own? Of course, I don't know for sure that the SES is due to a MAF code...

However, the truck runs great! I drove it about 15 miles to warm it up and to burp the cooling system. Makes so much power! It purrs... And, no excessive pressure in the cooling system. Yay!

DmaxMaverick

07-29-2021, 11:19

Your Predator should at least be able to read and clear codes on any LB7, even if married to another VIN. It won't allow any programming, but should read codes fine. I have an early model married to my 2001, and it will read all LB7 and some 04-05 LLY trucks (2006 LLY was a transition), as well as a bunch of other non- CanBus brands and models I've tried. If it doesn't read, check that the OBD port has 12V power, which is required. If it doesn't have power, the tool will seem to power up, but won't do anything (communication error), like plugging it in with the key off, on a truck that's known to work.

The MAF codes are immediate, meaning the PCM only acts if the code condition is presently active. Otherwise, it will remain in history for several start and warming cycles, with the SES lamp on. After the SES turns off, it will remain in history for 40 cycles, IIRC. If you have an active MAF code, you should notice the engine running different. It resorts to a default fueling map, which is very conservative. Unplug the MAF and give it a test. If you don't notice a difference, then it's still faulting that series of codes.

More Power

07-29-2021, 13:37

The Predator powers up, and says" Establishing Communications..." or some such, but stays there for as long as I have patience for (with the key in the "RUN" position).

There is unswitched 12v power on pin 16 and a solid ground on pin 4.

https://pinoutguide.com/CarElectronics/gm_car_obd_ii_pinout.shtml

By the way, this lack of communications was present before the tear-down. I wanted to record the injector fuel rates before beginning, but couldn't. And, this truck is running a Kennedy ECM, if that makes any difference...

Update Friday morning: I started the truck last evening, and saw that the SES lamp was gone. Apparently, the prescribed number of ign/start/warmup/cycles allowed the SES to go out. Still a puzzle why Lil Red's test port doesn't allow connection to the ECM. The wiring harnesses were all new factory items when the truck was first put together...

DmaxMaverick

07-30-2021, 08:42

I suspect the ECM plays at least a part in it. I've used 3 Predator tools on several trucks, and some of them had Hypertech programming or plug-in modules in them, and it was able to read/clear codes, as well as read real-time data. I mention the 12V power at the connector because some of them had the power missing at key-off, but worked once keyed on. There were probably other issues at play that I don't recall, but it's happened more than once. It may have been due to a power module or some harness hacking. If yours powers the tool before keying on, it isn't the issue. You possibly could have used the PCM from the 2001 in Lil Red to read the engine data. It may still have some use for benchmark data, and for a comparison between the two, if it works. I don't know if it will, and I've never tried it.

Robyn

08-02-2021, 11:50

Also.....doing the job yourself ensures that it gets done right in many cases.....YOU are going to take a second look at anything that seems a tad hinky.....as compared to the shop mechanic that MAY NOT give it a second thought....

More Power

08-03-2021, 07:34

You're right Robyn.

Mechanics and shop owners have a somewhat different motivation than do owners. They are worried about come-backs and liability, as well as producing a satisfied customer (or they should be). Shops also rely on their mechanic staff to do all that, while trying to keep the best mechanics and make the shop profitable (the really talented mechanics usually go out on their own). Shops have a lot of competing interests, which is partly why they do the "As Long As We're in There" routine with up-selling every job that comes in. There are a lot of good mechanics out there and there are a lot that aren't. I've heard so many horror stories through the years from GM diesel owners.

Jim

Robyn

08-04-2021, 05:44

I agree on the "Upselling" many times these things are done to "Cover the dealer/shops butt"

A side story.

My tenant that lives in the lower level of our place has a 2002 Jeep Cherokee with a V8
It has been giving issues off and on for a few weeks now.
I DO NOT WANT TO BE HER "GO TO MECHANIC" although on occasion I have wrenched on her rig to get it going so she can make it to work....(Important if I expect rent payment)

The Jeep started stalling.....I grabbed the scan tool and checked it out..../A failing crank sensor..

She took it to a shop close to her work....They installed the new sensor.....On the way home it died about 4 blocks from the shop....

Shop sends the mobile unit out and he determines that the tranny is burnt up and needs replacing.. Hmmmmmmmmmmmmmmmmmmm

She calls me and I told her....DO NOT DO ANYTHING.....NURSE IT HOME.

I check the tranny fluid....PINK AND SMELLS PURRRRRRRRRRRRRRRRRFECT.

Tranny shifts fine.
Every so often at light throttle the engine would just die....

Throttle position sensor and the idle air control are suspect in my book..

The TPS was replaced about 3 years ago due to a similar issue (Engine speed surging up and down)

I suspect the NAPA part that was installed (Made in China) is giving up....

Idle air control dirty with carbon and crud can and does cause stalling......

Sharis called another shop....told them the story....

Fella puts his scan tool on the JEEP and tells her she needs a new ECM

Nobody has hit on the IAC and TPS
She has been quoted MEGA $$$$$$$$$$$$$$$$$$$$$$$$$$$ to chase this anomaly....of which none of the FIXES will do anything accept take her money..

What I have seen so far is mechanics that rely waaaaaaay too much on the magic box scan tools.

If the tool does not tell them what's wrong....they default to a WILD ASS GUESS.....

They need to learn "Butt dyno" and basic automotive skills.

If the scanner is not showing anything then its not electronic (Generally)

Back in the day.....when a screw driver and a crescent wrench were king....We had to THINK

I digress

Glad to hear that the Daughter is interested in learning the art of swinging a wrench...
Definitely be good for her to have a good handle on all things automotive.....Then she will be able to know when she is being told BS....

More Power

08-04-2021, 07:48

I suspect the NAPA part that was installed (Made in China) is giving up....

Not much available in any auto parts store that's not made in china... They've all turned into Harbor Freight. (although HF is starting to grow on me... I bought a number of wrenches from them recently, including a 3' long 3/4" breaker bar - now that's a manly wrench!)

Robyn

08-04-2021, 10:09

Yes indeed
Big Ma break stuff type wrench

I avoid screw drivers and such. Pretty much junk
I have a set of impact sockets I bought back in the 80’s when HF was mail order only

Still 100% shape and been beat unmercifully over the decades

I have several power tools from HF
No complaints
Just need to treat them with a bit of care as opposed to tossing in the truck with a heavy hand

I have a 12” double miter saw, a hand held band saw snd a few other tools

All are great tools

Several air tools including my air compressor came from HF
My old air compressor died after 30 plus years of serious abuse

Ran to HF and picked up the Squatty top compressor unit on wheels

Works great
The Cat project has already put 16 hours on the beast

I have one of their multi meters snd it’s been great too

Most stuff from HF is great for hobby shop or moderate use and will live a long time if taken any dirt of care of

Oil the air tools and be somewhat careful of plastic handles and such

I have an ancient horizontal metal band saw that still fills in when we need two machines

My Son in law picked up a nice Jet band saw that has the protractor head on it

He found it sitting in a driveway near his house with a sign FOR Sale
This model is about $1000 and we got it for $500
Just requires a very easy feed or the band will pop off
That was common in that model

But for the price ..: good tool

HF is my Toy store

I will not buy their 18 bolt stuff

The 1plus from Home Depot have been great
Have Ridgid brand too
Both great tools

I like having several tools that use one battery and charger
The lithium ion batteries are sooooooo much better than the old chemistry stuff

Got one of those battery chain saws
Great for that little job that you don’t want to go get the gas saw and fool with it....

Tools ... great toys for busy hands

arveetek

08-04-2021, 12:11

Harbor Freight quality has really increased a bunch lately, it appears to me. However, so have the prices. Case in point - their "pro" 1/2" drive torque wrench is $109. I picked up a Craftsmen brand from Lowes for $89.

Casey

Robyn

08-10-2021, 06:27

Looking great.

I have seen this view before a few times...... always a good feeling when ya get the crank in and start stuffing the little soldiers back in their holes.....

The sorting through the parts boxes is always fun....especially when others have torn stuff apart.

When the Dahooley came down the last time I knew it was going to be a lengthly period of time until it went back together.

Stopped at the grocery store and grabbed a few boxes of the various sizes of plastic zip lock bags.

Bagged and tagged all the bolts. nuts and sundry other small items.

Made the reassemble a breeze....No matter what was happening, a quick sort through the bags of goodies and whatever was needed was in hand and ready to go.

When the hood was closed for the final time ....all the bags were empty and nothing missing or left over.

Really makes me wonder why some folks toss all the bolts and such in a bucket and then have to sort through it all later....

Too much like work and frustration me thinks......

More Power

08-10-2021, 08:07

Bagged and tagged all the bolts. nuts and sundry other small items.

Yup... We used about 20 such cups for hardware during the Duramax head gaskets jobs, and I kept as much of the hardware as was practical with the items being removed. All of this speeds the reassembly process considerably. Unfortunately, the 6.5 was disassembled by someone who didn't know - who hadn't done this before, as evidenced by the fact that they ruined the original crankshaft getting it out of the block (gouged journals) and not protecting vulnerable inner parts from moisture (i.e. most of the lifters were ruined by rust and none of it was kept clean). There are about a dozen cups with hardware, but most weren't labeled (or the lettering rubbed off) and there appears to be a mixture of fasteners in some cups. Reminds me of the time that, as a teen in the '60s, I bought a basket case 1938 Harley Knucklehead for $75 that I turned into a bobber. Fun times! My spine winces a bit when I think of riding that bike. ;)

Robyn

08-10-2021, 11:46

Sad to see stuff trashed.....but it happens.

arveetek

08-13-2021, 08:12

I watched an ARP video a while back where they discussed the "elastic" clamping load supplied by properly installed and torqued Series-2000 head studs produced for the Duramax. I like it that the ~$650 head studs have some elasticity designed-in.

However, we know that GM is still using TTY bolts in the newest L5P Duramax, which is rated for 445 hp / 910 lb-ft - and rated for up to a 35,000-lb GCVWR.

I interviewed the "Duramax Power Tour" team in 2000, who drove an LB7 equipped 3500-series truck towing a 20,000-lb event trailer. I rode in that truck as they wailed on it, on the I-90 continental divide pass just east of Butte, Montana. I asked them if they drove it like that all the time. I was told yes... They put in excess of 20,000 miles on that truck - hammer down all the time. I can also point to a 750,000-mile LLY Duramax used to commercial tow RV trailers all over North America, that I wrote about a few years ago. GM could acquire head studs equal to those offered by ARP (maybe even contract with them to provide) if they felt it was necessary.

I have a couple of debate points about studs that are hard to answer and difficult to challenge. 1- The aftermarket pushes anything that they can sell - ("while you're in there") type of stuff, including head studs. 2- Studs are simply easier to install than TTY bolts. You must mark the heads of each TTY bolt during the two angle tightening sequences or you'll mess up the installation. With studs, you only use a torque wrench. If you forget one or get out of sequence, it's really easy to check what the torque is for that stud. Personally, I think this is why many vendors/mechanics push studs (sell more expensive stuff and they are easier to install). Otherwise, they would/could point to actual durability tests involving direct comparisons between engines using head studs and TTY bolts (fleets would be the best source of information. Second best would be an accumulation of real-world reports from actual owners - like the story I did on the 751k mile LLY Duramax). For most, these head gaskets will wear out long before any real comparison can be done on the veracity of claims otherwise.

I have the opportunity to purchase some new ARP head studs for my 6.5L for the same cost as new TTY head bolts. Is there any reason NOT to use head studs in my application? This is a stock 6.5L with 375K on the clock and no other issues other than a blown head gasket. John Kennedy recommends studs.

Thanks,

Casey

More Power

08-13-2021, 08:47

I have the opportunity to purchase some new ARP head studs for my 6.5L for the same cost as new TTY head bolts. Is there any reason NOT to use head studs in my application? This is a stock 6.5L with 375K on the clock and no other issues other than a blown head gasket. John Kennedy recommends studs.

Thanks,

Casey

I can easily make the case for TTY - which includes the quote you included in your post. What was not in that quote was the head gasket durability I saw with our 6.5TD Power Project, using TTY bolts (300K miles of mostly towing/performance miles without a single head gasket problem).

It's disappointing that "some" get perturbed when asked to provide support for their position. I don't understand it. If studs are better, state why you believe that... I have nothing to gain otherwise by promoting one type of fastener over another (I actually lost a vendor over this very issue). As an information resource (thedieselpage.com) I have more to gain by promoting the "best" option. There are several criteria for what could be considered "best". "Best" could defined as proven better - sorta like how the FDA approves new drugs (blind studies - direct comparisons). "Best" could be defined as being more than adequate for the vast majority of the owners while saving them a lot of money in the cost of fasteners. What's not "best" is theoretical or an arm chair opinion. I would ask the stud advocates to put some verifiable high mileage examples of head stud usage on the table to consider - like the following high mileage TTY head bolt example I talked about a couple of years ago - 772,470 miles, which backs up the story I did on the 751k C2500 Duramax RV hauler (https://www.thedieselpage.com/duramax/750kduramaxc.htm) and our own 300k-mile 6.5TD Power project... Read more about high mileage Duramax trucks here: https://www.thedieselpageforums.com/tdpforum/showthread.php?36692-750K-Mile-Duramax-March-updates

https://www.thedieselpage.com/images/Duramax-head-gasket/772k-Duramax.jpg

It used to be back in the early days of the 6.2/6.5 that GM's head gasket suppliers hadn't figured out how to design a gasket that worked for these engines. Far too many head gaskets failed in these engines because of poor gasket design, and that's when the aftermarket (and others) began advocating for studs for the 6.2L/6.5L. Then one day Fel-Pro designed the best head gasket, and head gasket failures almost disappeared. Turns out that the problem was never the fastener but the gasket design. But, old opinions die hard. By the way... throughout the early years of the 6.2L diesel engine production, GM used head bolts that were not TTY. They were simply torqued to a specified torque value in steps... like stud nuts are now. GM could have stayed with non-yielding head bolts, but they switched to TTY early and continued through to the end of their own production of this engine, and AMG continued to use TTY when they took over 6.5 production.

So, to answer your question.... because of their elastic head clamping design that compensates for thermal cycles and gasket compression (and my own verifiable long-term experience/success with them), I prefer TTY, especially for the 6.5. Now, for the Duramax, if cost is taken out of the equation, it's more of a toss-up in choice except perhaps for a high power (2x+) application, then ARP's engineering data "begins" to sway my opinion. But, even that is simply theoretical. ARP's own ad claims in the Northern Auto Parts catalog, when talking about diesel stud kits, say that their studs are preferred among "racing" enthusiasts. That said, I'm quite content in my choice of TTY for Lil Red's Duramax because it has been retired from any sort of racing/dyno/nitrous duty. The 6.5 I'm putting together right now will get Fel-Pro TTY head bolts along with Fel-Pro head gaskets... just like our 6.5TD Power Project did in 1999. Besides, due to the limitations in fuel delivery of the DS/DB fuel injection system, the 6.5 can't be made to produce a horsepower level that justifies studs... in my humble opinion.

Jim

Robyn

08-13-2021, 10:06

GM spent a buttload of $$$$$ designing things (Bean counters not included in the equation)

But even the best engineering will not always stand up to road testing by "Bubba"

I think you are pretty close to the mark....

The Monday morning quarter backers.....always...woulda, shoulda, coulda types always have an answer to every issue.. "My buddies uncles shop" does it this way......

Ah well.

Such is life....

More Power

08-13-2021, 14:18

GM spent a buttload of $$$$$ designing things (Bean counters not included in the equation)

...

I'd bet that "if" GM believed studs were best, they could contract with ARP or another manufacturer to provide head studs for the Duramax. DMAX has produced millions of these engines. That should allow for a pretty deep discount on quantity buying.

By the way, the engine shop I visited, to get my GMC's aluminum heads resurfaced, also builds Duramax engines for their retail market. They offer a 5 year warranty on their top of the line Duramax engines, and they only use ARP head studs and Mahle gaskets. The owner is a nice guy, and I didn't press him by asking "how he knows they're best?". I was there to make friends. Sometimes people forget or simply don't know how much experience I have with these engines - and how many people I've talked to in more than 2 decades. I always allow room for others to have their own opinion, even if it is based on theory or... If their position is fixed, I move on.

An additional item I found during the Duramax head gasket replacement project(s)... The Mahle head gaskets made for the Duramax don't seem to compress overnight after having the fasteners (either stud nuts or TTY bolts) torqued to their second-to-last torque setting (59 ft-lbs). When checked the next morning, the torque setting was still right where I left it. So, there's no need to pause overnight, then re-torque to 59 ft-lbs the next morning, before moving on to the last step in stud/TTY tightening.

Jim

Robyn

08-13-2021, 16:47

Allowing folks their latitude is usually a great plan to make inroads.....

The folks that really irritate me are those that say.....WHATEVER IT IS ....You can't do it that way...."Why" BECAUSE....IT WON'T WORK.....

No explanation....just because....

Arrrrrrrrgh....

More Power

08-18-2021, 09:36

I haven't talked much about the injectors I used for the two Duramax head gasket projects discussed in this topic thread, and after having lived with the choices I've made for some weeks now, I think I have enough information to talk about the differences between the original VCO type injectors (stock type used in the LB7) and the more recently available SAC type that I installed in my GMC during the head gasket replacement.

First, a little background: The original 2001-2004 LB7 high pressure common rail fuel injection system operates at up to 23,000-psi fuel rail pressure. The more recent model year Duramax operates with up to 29,000-psi rail pressure. We all know that high pressure liquids can erode even hardened components. For example, the Duramax conversion motor mounts (https://www.thedieselpage.com/conversionmounts.htm)we sell here at thedieselpage.com are made from 3/16" plate steel cut from large sheets using a computer controlled water jet system. It cleanly and smoothly cuts steel plate like butter. The Bosch fuel injectors use hardened components designed to deal with the high pressure diesel fuel... but, there is a design difference between injectors made to operate at up to 23,000-psi and those designed to work at up to 29,000-psi. The aftermarket (S&S Diesel) began offering the SAC type injectors for the LB7 in about 2018, which combine some of the 29,000-psi nozzle components in an injector body that fits the LB7. Longer nozzle life is the leading ad claim. That's the upside... but, is there a downside? Turns out... yes...

According to the web site: https://powerdrivendiesel.com/difference-vco-sac-injectors/ , the acronym VCO is derived from (Valve Covering Orifice), where SAC style nozzles utilize a different shaped orifice that is said to provide more longevity. The site didn't say what the letters SAC mean..., but they do mention a difference in the level of combustion rattle (noise) produced by the engine depending on which type of injector is installed - confirming what I experienced. I didn't know this before the SAC installation...

In real terms, there are a few differences you will notice the first time you start your LB7 Duramax after installing the new SAC injectors.

Originally equipped with VCO, my 2001 GMC got the new stock flow rate SAC type injectors during re-assembly. After all this work, the engine appears to start almost instantly with a much crisper "ccrraacckk" sound. While motoring around town, you can hear more combustion rattle in general along with a background of light secondary rattle (like shaking an empty soup can with a dozen BBs inside). I don't see anything in the way of smoke, either during a cold start (it's summertime) or when accelerating hard - boost goes to 20-psi. Seems to be very clean for a 141,000 mile engine. At secondary road speeds (55-65-ish) the increase in combustion rattle produced by the SAC injectors can be a bit annoying... it's as though the pilot injection has been reduced or is only marginally effective. Haven't had it on the Interstate yet. By the way, my GMC is running with a 100% stock factory-programmed ECM and without any sort of power adder. There is no SES light.

For Lil Red, I re-installed the very same factory original VCO injectors that this particular LB7 came with - now with just over 8,000 miles on it. Not surprisingly, the engine sounds exactly like it did before the head gasket replacement. Its combustion rattle is relatively quiet, just like it was before. In terms of combustion rattle, it's noticeably quieter now than the GMC... By the way, I went to considerable lengths to keep Lil Red's injectors clean and uncontaminated during dis-assembly, storage and re-assembly. I must have done a good enough job because the engine runs just as smoothly now as it did before all of the engine work.

The original VCO injectors in my GMC crew cab ran to about 120,000 miles before #2 set a fuel-rate balance code (P0302). Not long after, a local diesel shop installed a full set of VCO reman injectors for me (I know, I know... I should have done it...). After about 4 years and ~20,000 miles (now 140,000 miles total on the truck), I was beginning to see a little blue fuel smoke at a cold start that quickly went away and didn't return till the next cold start. It ran well enough with those reman VCO injectors, and the combustion rattle was just like it was with the factory original set of injectors. I decided not to re-install this 20k-mile set of injectors during the head gasket replacement because of the blue puff at a cold start - "as long as you're in there", I thought. By the way, I've always used a commercial diesel fuel treatment in this truck (lubricity, cetane, anti-corrosion, cleaner, etc.). I had originally planned on taking the GMC's injectors to a local certified shop for testing and cleaning (if they would do it), then re-install them, but doing the work myself saved so much money that I splurged a bit on new reman injectors.

Going forward, the only reason I can see for choosing the SAC type injectors is longer life (theoretical - yet unproven), which would be a good reason... but, I know now that the VCO type injectors offer a much quieter operation - and that's important to me as well.

What would I choose if doing the GMC again? I'm thinking I'd choose VCO... And, I would investigate the service life data and cost differences comparing reman Bosch injectors with new Bosch injectors as part of the decision making process, as well as looking to solve some of these injector problems on my own work bench using the available replacement parts. All that said, I'm glad I reinstalled the original VCO injectors in Lil Red.

Jim

Robyn

08-18-2021, 09:43

Interesting stuff.....

DieselDavy

08-22-2021, 18:00

Hey Jim,
I'm wondering if John could spin some new code to quiet the GMC down. See what he says.....

More Power

08-23-2021, 11:54

As an aside... During the opening phase of these two head gasket replacement projects I became acutely aware of the enormous cost potential, especially if a truck owner took the advice of the "replace it as long as you're in there" crowd and replaced or upgraded everything. Doesn't take long to cross the line in economic sanity.

As my work progressed, I assumed I'd need a water pump for the GMC, even though it had been replaced just 3 years earlier. I thought this because I could smell hot coolant after a drive, parking, then walking around the front of the truck. I just assumed the water pump seal had surrendered to the excess pressure, so I bought a new water pump from Kennedy (like most things I needed) so it could be replaced as part of this head gasket replacement project.

During the tear-down I noticed that most fittings/joints/connections in the thermostat housing area had been oozing coolant for quite some time. The coolant ooze had run down the front of the engine behind the fan pulley assembly, producing the hot coolant smell. That made me curious, so I then carefully examined the weep hole on the bottom of the water pump, to see if it showed any evidence of coolant leakage. That weep hole is somewhat hard to see - it takes some effort to be sure about it. Turns out the weep hole was bone dry and was without any dried coolant residue. So, there were no water pump seal leaks. As a consequence, I didn't replace that 3 year old water pump. It wasn't leaking then and still isn't. I left the brand new water pump on the shelf, "standing by, just in case" for the Lil Red project.

When Lil Red was at the same place in its head gasket replacement, I examined its water pump weep hole. Nary a hint of leakage... So, I kept the new Kennedy AC Delco water pump (with welded impeller) on the shelf. I've driven Lil Red about 4,000 miles and the GMC about 8,000 miles since replacing the head gaskets (now ~13 months after the fact - September 23, 2022). Everything remains perfectly dry and without a whiff of a coolant leak... After having done these two head gasket replacements, I now know that a water pump replacement is, by comparison, cake (I've participated in one complete WP replacement)... Besides, I still have that new Harbor Freight 3 foot long 3/4" breaker bar I mentioned a few weeks ago, just in case I need to remove the damper during a water pump replacement. ;)

More Power

08-23-2021, 12:13

Hey Jim,
I'm wondering if John could spin some new code to quiet the GMC down. See what he says.....

I wondered about that. I suspect he's reading this thread.

Experience... you'd think that at some point a person would have a good handle on what to ask - live long enough and you'd become that wise old sage. Seems I'm still learning...

S&S has an info page that talks about and discusses the benefits of SAC. I should have asked them about downsides... didn't see any on their web site. I thought maybe I'd screwed up during the install because the truck was so much noisier with combustion rattle... Then I started doing a little research online... I also wonder about potential impacts to power and fuel economy - by comparison to VCO. I've been tracking fuel economy in the GMC... I'll report what I find when I have enough information to form an opinion. Jim

On edit (9/15/2021): Fuel economy so far... has been in the range of 15-17 mpg for mostly local driving, so my guess is that the fuel economy hasn't been affected all that much - that's about what it did pre-head gaskets with the VCO injectors. I'll know more when we drive it on the interstate for a few hundreds. The GMC has nearly 2,000 miles on it since the head gasket replacement.

On edit (2/1/2023): The GMC is coming up on 10,000 miles since the head gasket and injector replacement. I've gotten more or less used to the increase in combustion rattle. The engine runs smoothly, and continues to perform very well without any sort of problem. It's wonderful knowing that I can jump in the truck, and can go anywhere without worrying about whether or not the cooling system will dump its contents out onto the highway. We love this truck. I'd rather drive it than our Chevy Malibu, anytime, anywhere - for the room, the comfort, and the safety...

arveetek

08-23-2021, 12:24

I thought maybe I'd screwed up during the install because the truck was so much noisier with combustion rattle...

Sounds like a good thing to me! :D That's actually one of the things I don't like about the newer diesels... they are too quiet. I love the older, clattering diesels.

Casey

JohnC

08-25-2021, 05:39

That's actually one of the things I don't like about the newer diesels... they are too quiet. I love the older, clattering diesels.

When I brought our brandy new 2006 Duramax home, my wife, who had been around Diesels all her life, said "it's not a Diesel!" in all seriousness, thinking her husband had made yet another huge blunder! ;)

Robyn

08-25-2021, 07:01

I think the reason that the newer diesels are so much quieter is to satisfy the "City dwellers" that are offended by everything.

The common rail and pilot injection technology really made all this stuff happen
Just to sort of play the devils advocate here...

After owning many diesels....OLDS 5.7...GM 6.2/6.5 a couple Detroit 2 strokes and a 3406E 500 HP Cat.
The interior cab noise levels does tend to beat ya up after a while....So why not make it quieter...
With the computer control and the pulsed injection....Does make the long trip much more relaxing.....

Likely has a lot to do with meeting emission requirements too....

DmaxMaverick

08-25-2021, 07:09

Simple. Turn up the radio or turn down your hearing aid.

Robyn

08-25-2021, 07:50

ROFLMAO

Pretty much......
Trucks used to be "Trucks"
These were hard working, hard driving beasts that offered little if any real creature comforts.
Rode like a buck board....
Power steering....Wasssssat ???

I had a 1967 IH 3/4 ton 4x4
Gawd that was a beast....The transfer case shifter looked like the Johnson bar off a late 1800's steam locomotive.. Damned lever weight 15 lbs Cast steel....

Now that was a truck.....Everything about it was brute force.....

No power steering either....let alone AC and other fluffy stuff we have come to expect...

Crank windows, no radio....Stereo with surround sound ....Say whaaaaaaaaaaaaaaaat...

More Power

08-25-2021, 13:02

Simple. Turn up the radio or turn down your hearing aid.

What was that???

Back about 1992 or thereabouts my sister-in-law's husband (who owned a Ford diesel pickup at the time) test drove a then new 1992 Dodge 12v Cummins. I asked him afterward if he was planning to buy a Dodge... He said: "If I wanted a truck that rode like, drove like and sounded like a road grader, I'd buy a road grader." It was funny when he told it... He still drives Ford diesels... has a couple of new ones.. pretty quiet too.

Daughter doesn't think the GMC is too noisy either, and I don't yet have a hearing aid...

It's a little amusing, but I'm also embarking on a mission to quiet down Lil Red... not the combustion rattle (that's quiet enough), but the overall truck noise... Remember, this was a 5.7L gas truck originally, so it doesn't have a lot in the way of sound abatement. So, I'll be installing a muffler along with more padding (firewall pad, under-hood pad and a rubber mat for the bed). Everything is an echo chamber now.

Robyn

08-25-2021, 19:07

Yeah buddy

Tain't lived till you have driven a big rig with a Detroit V12....The O'L Buzzin dozen...
A SWEET SOUND INDEED

a5150nut

08-26-2021, 06:38

Yeah buddy

Tain't lived till you have driven a big rig with a Detroit V12....The O'L Buzzin dozen...
A SWEET SOUND INDEED
Used to run Euclid SS40 3 axle scrapers. 1271 Detroit and 4 speed Alison, with open sided hood and 6in well pipe with a steel seat pan welded on top of it. Had 1/2 in of cotton padding in a vinyl covering. Always carry a spare set of cloths because when they blew a hydraulic line you were getting a bath.
Ahaaaa, the good old days!

Robyn

08-28-2021, 06:48

Gotta love the smell of hot hydraulic oil eh ????

a5150nut

08-29-2021, 17:43

Gotta love the smell of hot hydraulic oil eh ????

Especially with the smell of scalded flesh. And if you dont change cloths it will blister your skin.

Robyn

08-30-2021, 05:29

Yeah buddy
Even the cold oil will likely give ya a nasty rash if it's not washed off....

a5150nut

08-30-2021, 19:28

Yeah buddy
Even the cold oil will likely give ya a nasty rash if it's not washed off....

Back when I was a young apprentice on a lube truck if we got an operator that couldn't park in the lineup correctly after several warnings we would dribble diesel on the seat cushion. They would have a red ass after a couple hours the next day.

Robyn

08-31-2021, 04:39

HAAAAAAAAAAAAAAAAAAA....ROFLMAO

Yup...that will do it...

More Power

09-01-2021, 07:51

Felt confident about the head gasket R&R so we took about a 300 mile overnight road trip with Lil Red on Mon/Tue. No oil use, no coolant loss and no abnormal pressure buildup in the cooling system. :o

https://www.thedieselpage.com/images/Duramax-head-gasket/LilRed-Dash-85-aa.jpg

This was taken on I-90 about 60 miles east of Missoula Montana, headed west/home. The speed limit on I-90 here is 80-mph. The 3.42 gearing and 275/55R20 tires make for fairly tall gearing. The truck loves it. We crossed the continental divide on US-12 coming/going. Truck stays in OD with ~8-10 psi boost and ~1000 degrees EGT at 60-70 mph while climbing the grade (there are some corners). So far so good!

Edit: The JK 600+hp ECM race programming (did 632 on it's last dyno pull) was replaced recently with a Kennedy program that includes both a stock power/fuel economy setting plus a +100 horsepower switchable setting. In addition, John corrected the speedometer for the 3.42 differential gearing and tire size as part of his programming for me - thanks John. I haven't used the +100 hp setting yet. Wanted the new head gaskets and cup sealing to settle in a bit.

I don't know if you can see it in any of the prior images, but this engine is also running a Banks "Big Head" wastegate controller, which has a larger diaphragm than the stock one, and it includes an adjustable control rod - to control spring pre-load (thus boost pressure). Current rod adjustment produces 25-psi boost pressure during a brief full pedal run - still goes like a bat even with stock power. The truck delivered 22.13-mpg on the last fill-up (250.1 miles), which was a good part of this trip. Considering the speed...

Jim

More Power

04-27-2022, 09:25

Just an update...

The GMC now has about 6500 miles on it since the head gasket replacement. I bought the oil and filter for it a week or so ago, and will change it soon. This'll be the first oil change since the work. It's been such a relief to not have excessive pressure in the cooling system no matter how long or short the drive. We've driven the truck on several trips of a few hundred miles each - mostly this past winter when the roads were awful. The engine starts, runs and drives very well. Fuel economy on winter fuel has mostly been in the 18-mpg range on trips and high 16s-low 17s locally.

Lil Red only has about 1500 or so miles on it since the head gaskets. It too, runs very well without a hint of excessive cooling system pressure. I did notice a very minor fuel leak somewhere near the driver side fuel rail. I need to remove some stuff covering the area and then re-torque the fittings.

More Power

06-17-2022, 09:48

Update! It's finally here, about 13 months since the project began.

https://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=6546&d=1655244034

https://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=6545&d=1655244034

Go here to learn more: https://www.thedieselpage.com/duramaxdieselserviceguide.htm
(https://www.thedieselpage.com/duramaxdieselserviceguide.htm)

If I can find it, I'll post a pic of the quote I received a year ago from our local GM dealership for just replacing the head gaskets - $6500. That didn't include injectors or much of anything else... other than head gaskets and head bolts. That was the biggest incentive to do the work ourselves (daughter and I). How hard could it be? In hindsight, it wasn't that bad, but going in - there were so many unknowns that it was a little scary. Now, not so much! Thanks to JK, Greg and others for tips, and for everyone's encouragement. Jim

Robyn

06-18-2022, 04:07

Looks great Jim.

"Doing the exact same repair yourself would reduce the cost to a total of only about $3500. This is why more of us are finding the will to work on our out-of-warranty trucks. In the end, doing the work yourself will provide far more value and truck performance/longevity than you could expect by hiring someone else to work on your Duramax."

You got that spot on....
The quality of the "$10,000.00 job if done at the dealer is suspect IMHO....
Doing your own work certainly does add the fact that as the owner.....You care far more about the outcome of things rather than the guy who is only interested in beating the flat rate time...

The attention to details and taking a second look at the little things that might well come back to bite you if you don't deal with them properly......

I have not been closer than looking over the fender at a Dmax ....but certainly appreciate the work needed to gitterdone...

Good one....:D

More Power

06-20-2022, 14:23

Thanks Robyn.

Yukon6.2

07-28-2022, 09:09

More Power

07-29-2022, 08:39

My 2001 3500 is making pressure and have idle smoke when i haven't ATF'ed it in a while.
As much as i have been putting it off,i am going to have to start looking for tools and parts to do the head gaskets and injectors.
First step will be to add the new books to my library.
I was told that the injectors were done at one point,but there was no paper history of it.My assumption is that if they were changed the lines weren't.Plus there is a chance the injector tubes are causing the cooling system pressure.Is there a way to point to the gaskets or injector tubes?
Thanks

After having done two sets of head gaskets and re-sealed 16 injector cups, it's my opinion that the LB7 injector cups are rarely the problem with excessive pressure in the cooling system... Unless there's been work there in the recent past, and it wasn't done right.

Thermal cycles are, I believe, the biggest contributor to gasket failure... Time and starts... The gaskets simply wear out. Gasket replacement isn't that bad. The new Duramax Service Guide walks you through the complete process showing what tools, supplies and items you'll need, as well as showing you how to do each step. Lots of helpful tips and practical experience. I'll even give you my phone number if you need it - it's right there in the Service Guide. Both of these engines are running great... My GMC now has going on 8,000 miles since the gaskets and Lil Red about 4,000 miles. There have been no problems with either truck other than a couple of fuel leaks that were super easy to resolve. After far too long a time, it's so nice not seeing excessive pressure in the cooling system... Both trucks are dependable enough to drive across the country without worrying about the engines. ;)

More Power

04-17-2023, 08:24

The past 10,000 miles and 18 months have been pretty amazing. I lived with the excess pressure in the cooling system for several years prior to the head gasket replacement, which limited the usefulness of the truck. It had become a "local-only" truck. But, for the past 18 months+, I could drive it anywhere, and I have... including several 250 mile trips to see our daughter during the last 2 winters.

The cooling system over-pressure was eliminated by replacing the head gaskets. Now, you can squeeze the upper radiator hose right after driving the truck, or after sitting over night and not have a hard hose. Before, the radiator hose felt more like a kid's bike tire (really hard) when the engine was near operating temperature. In addition, there is no "swooosh" when opening the coolant surge tank cap when the engine has cooled. An over-pressure problem left the cooling system pressurized even after sitting overnight.

However, I do have an oozing coolant leak - the small 10mm coolant hose located behind the fan pulley assembly. I had installed a new hose, but used the same screw clamps that a local mechanic had installed during a water pump replacement some years ago. I really don't like screw clamps for engine coolant hoses, preferring the OE spring clamps used by GM. For the head gasket replacement in Lil Red, I was able to re-use all of the OE coolant hoses and OE clamps. Lil Red's LB7 hasn't leaked a drop since it got new head gaskets.

So, my advice... Learn how to remove/re-install the OE clamps. Your engine is better off with them. ;)

DmaxMaverick

04-17-2023, 09:08

More Power

04-18-2023, 12:31

That little hose section behind the fan pulley is the turbo coolant supply. I've replaced mine twice, as well as a bunch of others. Not too complicated or difficult (replaced one in an RV park in less than an hour, once). I prefer the OEM spring clamps, as well, but used screw clamps the last time I replaced the line. I double-clamped it (4 clamps, 2 at each end), and it hasn't leaked since. I reused the OEM spring clamps the first time, and it began weeping rather quickly. As far as I know, mine wasn't/isn't pressurizing the coolant system, such as with a head gasket leak. GM/Duramax surely could have located the soft connection in a better place.

Thanks... Second the notion that GM could have located that hose somewhere with a little better access...

I may try a double screw clamp. The end with the best access is the one oozing.

By the way... And for everyone else, that hose is a 10mm internal dimension coolant hose. It looks like it may be 3/8", but 3/8" is a little small. The hose can be saved by squirting a little coolant on the pipe it is attached to and once the clamps have been loosened, work/move the hose all the way to the left (as you're facing the front of the engine). That should get you enough latitude to remove the coolant pipe that carries coolant to the turbocharger, or replace the hose/clamps if need be.

More Power

08-14-2023, 08:54

It's now been a little over 2 years, and the truck has accumulated nearly 13,000 miles since my daughter and I replaced the head gaskets, injectors and injector fuel lines, and resealed the injector cups, resurfaced the head decks and set the valve lash in my 2001 GMC's Duramax 6600. The truck continues to run great, and there has not been a single issue with the head gaskets or any other aspect of the tear-down and re-assembly (other than a minor fuel and coolant leak after the initial startup the first day after the service - that were easily taken care of). None of the head gasket service videos that I've seen online talk about how successful their repairs were over time. A rather important point, considering the "dubious" repair procedures shown in the videos... So, other than to share a little of Montana with you, that's the reason for this update - to talk about the success of the head gasket replacement project that was completed in June of 2021 - done the right way. ;)

https://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=7269&d=1692026290

Nearly a hundred miles from home, this pic was snapped on Thursday, August 10th looking north from an overlook situated above the southern end of the beautiful Flathead Lake here in western Montana. Just over the hill and to the left a couple of miles is the small town of Polson, Montana. However, our destination that day was to the right in this photo, on the eastern shore of the lake, to a public facility called Finley Point State Park. We had rented a cabin there for a few days. This trip was possible because the new head gaskets have made the truck a reliable member of the family again.

Flathead lake is among the largest freshwater lakes in the country, being 28 miles long, up to 15 miles wide, and 370 feet deep at its deepest point. The scenic value of this natural wonder is awe inspiring, especially when set against the glacially carved and rugged Mission Mountain Range just off camera to the right. This mountain range reminds me of the glacially carved topography found in Yosemite. Flathead Lake is the result of a very large glacier that had scooped out the lake bottom during the last ice age. This elevated overlook where the truck is sitting is a "terminal moraine" that had been bulldozed into place by that glacier, and which also defines the southern boundary of the Continental Ice Sheet that once covered all of Canada and a northern fraction of what would become the US's lower 48.

We were here, partly, to kayak and to try our hands at fishing. Flathead Lake contains Lake Trout up to 40", good sized Lake Whitefish, Kokanee salmon and several other species (bass, perch, etc). My experience with fishing the lake was pretty limited, but the Zimmerman bait/tackle shop in Ronan, MT set us up with a selection of the right gear, and showed us a chart with water depths describing where each species would be located. This time of year, the bigger fish are all in deeper water, so my daughter and I jigged for Whitefish using artificial lures in about 100-150 feet of water - offshore from Blue Bay. I caught one and had several others on the line. The Whitefish we battled were about 2+ lbs and about 24" in length. Though the limit was a hard-to-imagine 100 per day, we were just catch-release fishing. We found the Whitefish to be hard fighters when using light tackle, and when in a kayak!

We had beautiful weather this trip, and the many cherry orchards around the lake had produced a bountiful crop - there were many open fruit stands all along the roadways. The large Bing cherries were delicious! My daughter even fed a few cherries to a Whitetail doe and fawn just a few feet off the front porch of our rented cabin.

See my signature below for a link to a page that describes our printed and bound Duramax Diesel Service Guide book, which includes a number of service procedures for the Duramax 6600 - including a head gasket replacement project. Do it once, do it right. :)

Jim Bigley

PS - The name "Flathead" came about because of a native tribe that once inhabited this area. Their custom was to bind boards against the heads of younger members of their group, thus modifying their skull shape over time. This was similar to what was practiced by a few native tribes found in both North and South America.

Today, the southern half of Flathead Lake and continuing south for another 50 miles is all within the boundary of the beautiful Flathead Indian Reservation. There is much to see and do within the Reservation, and I encourage those visiting this area to take advantage of the opportunity. Fishing on the reservation requires a reservation permit - available at any license counter here in western Montana or online.

I've known and even worked with a few natives from this area - going back to when I was a teen, and up through the 1990's when I assisted their tribal college to complete the setup and repair of some science tech I was trained for at the University of Montana. We met and talked with a handful of natives during this August 2023 visit. They're still the real deal... This area is a bright spot among Indian reservations. It's beautiful here. You'll be blessed for having visited.

arveetek

08-16-2023, 11:37

Thanks for sharing, Jim! You definitely live in a beautiful part of the country. I've never been able to visit Montana, but it's on my to-do list.

Casey

More Power

10-27-2023, 12:19

I've mentioned here before that Youtube can be a fun place to hang out or learn something you didn't know. However, when it comes to working on your Duramax 6600, a little common sense can go a long way. Back in 2021, I did a search on YT about Duramax 6600 head gasket replacements... I found the most popular video in the list of those I watched to be one where the mechanic was using a horrible technique to prepare the block deck for new gaskets... Here's a screen grab. Yikes!

https://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=7421&d=1698432471

The above image would be appropriate if he was grinding off a half inch of body filler - but this is not appropriate prep for new head gaskets. To compound the problem, there is absolutely no attempt to prevent carborundum grinding grit and debris from falling into the lifter galley, onto the piston crowns or into the cooling passages. This is NOT how GM specifies the heads and block decks are to be prepared...

The next image shows what IS recommended by GM - to help prepare the Duramax 6600 head and block deck surfaces.

https://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=7422&d=1698433033

This is a 3"x4" steel block that was machined flat on a milling machine. GM recommends using a light oil (I used WD-40) with 600-grit wet/dry paper on the pictured steel block to prepare the cast iron block and aluminum head deck surfaces. I also stuffed the lifter galleys and piston crowns with clean shop rags, and any accumulating oily sludge was prevented from entering the cooling passages. Our Service Guide linked-to below shows how this is done.

The Duramax 6600 head gaskets require a certain smoothness for both the block and head deck surfaces. The design of the head gaskets require this smoothness, and the differing temperature coefficient of expansion between the aluminum heads and cast-iron block demands it. 600-grit provides that smoothness, when used with an absolutely flat steel block.

I had a local fabricator make this block for me, but you could create your own by using a 4" length of 3" steel angle iron. Then make it flat by using a series of coarse/fine grit wet/dry sand paper sheets on glass or a flat counter top. Round the edges before completing the job - so they can't dig into the aluminum heads.

The job of preparing the heads and block isn't that difficult and it goes pretty fast. Jim

a5150nut

10-27-2023, 17:03

More Power

10-31-2023, 11:14

I have found if i watch 5 or 6 YT Videos i can find something in one and something else in another. They all seem to leave out a little something that was critical or that made things easier.
But for the price you cant beat it

You're right. Though, discernment comes with experience. The video mentioned above was about an hour long - for a project that takes 40+ hours to complete (GM labor rate), so there's a lot left out - a lot of questions unanswered. And, certainly most of the hard parts of the job are left out - the same hard part(s) are left out in each video (I have a theory for why that's so). I watched several other videos for this topic, but found none gave the complete story - a proper story. The video channels all produced content that relied on the viewer to already have a good understanding of auto mechanics in general and Duramax head gasket replacement in particular - when in reality very few actual truck owners have that level of knowledge. These engines and fuel injection systems are complicated - risk of failure is significant, and the video creators never give the viewer a long-term follow-up. What's the price of failure or chronic nagging complications? This is why The Diesel Page has produced Guides that help owners do their own service work, and succeed in that effort.

I know a local Duramax owner who abused his stock Duramax till coolant leaked/poured out in several places (i.e. head gaskets, water pump seal, coolant surge tank overflow, etc). He then hired a local shop to build him an "indestructible" 1000-hp monster - forged pistons, aftermarket rods, big injectors, dual CP3 pumps, twin turbos, etc. It only lasted a couple of months, after the truck owner spent $20K on it. Knowing the story, I blame the shop for the eventual outcome and not properly managing the owner's expectations... An idiot behind the wheel can ruin just about anything. In the end, success sometimes boils down to experience...

More Power

11-01-2023, 10:36

I watched a Duramax engine-related video short last evening that was created by a white haired guy in a professional looking shop. The video focused on a Duramax 6600 engine sitting out of the truck with its heads removed. In that video, the white haired guy pointed to the top of a Duramax piston that had been partially melted by what he described as an injector failure. He said this extreme heat had damaged the piston crown and caused the piston to swell in the cylinder, resulting in both piston damage and cylinder damage.

Individual common-rail injectors can fail in ways that cause it to become a fierce blowtorch - a piston melting blowtorch. But, in my opinion, an injector failure wasn't the root of the problem in that video short. What he didn't point out was that other pistons also showed evidence of extreme scorching, produced by excessive fueling, which resulted in EGT temperatures well in excess of 1300 degrees F (maybe even 1500 degrees F). This scorching always produces a distinct and pronounced star pattern on the piston crowns - the melted piston in the video had that scorched star pattern on it. Think about what a Saturn 5 launch pad must have looked like after a moon shot.

My opinion, based on the images, was that the truck owner installed high-flow injectors and ran with a big program that put a lot of fuel into the engine. He then raced or pulled with it, which produced a combustion temperature that the piston(s) couldn't cope with.

The point... I believe the video producer didn't correctly diagnose or describe the problem... I found it curious that the shop owner didn't take the time to show the viewers what the other pistons looked like, and how he characterized their appearance. The video only showed an adjoining cylinder very briefly and incidentally - curious... Truck owners (and video viewers) need to know the whole story of what happened, to help them avoid a problem like that shown in the video. This must have been at least a $10,000 repair.

By way of comparison, here's what a normal Duramax piston crown looks like in a stock daily driver with 140,000 miles on it. There's only the faintest of star pattern on the outer rim, with no star pattern on the bowl.

https://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=7431&d=1698862480

In closing, a common-rail injector that fails in a way that allows it to spray unregulated amounts of fuel will likely set a cylinder balance code, will smoke at idle (and above), will run rough and excessive blow-by will huff white smoke out the oil fill pipe with the cap removed - if the engine is run long enough to damage a piston/cyl. I'm not sure how this would affect fuel rail pressures at idle, but I suspect there also may be low rail pressure codes. In other words, a Duramax owner should have ample warning that a serious problem exists - possibly even before damage has been done. An exception to this might be when a Duramax is being used to tow heavy while out on the highway, and the driver simply can't pull over/stop immediately due to safety concerns - he has to keep going. In this situation, it becomes a choice between dollars and sense.

Maybe someone who has experienced this sort of problem with their truck can help fill in the blanks on symptoms. Jim

More Power

11-24-2023, 11:03

https://youtube.com/shorts/pySyCI1lRq8?si=B-HunvXKqYnAoKzp

I know that the debate regarding whether to choose head studs or head bolts for a Duramax 6600 will likely never be completely resolved, but here's another voice that addresses the question... ;)

I like Gale Banks. I've met him personally a couple of times, had dinner with him, and we've talked on the phone/email. But... Now, to be fair, the image he uses in this video of block deck bolt thread failure is NOT of a Duramax 6600. I don't know what engine is represented by that pic. You can see in the image in a previous post (of mine) what the block deck actually looks like in a Duramax 6600. The bolt holes are much different, and far less likely to fail like that shown in the Banks video.

Still... I believe Banks would be running studs and selling his own stud kits if he thought studs were either necessary or even just a better choice. Studs are a fairly expensive option. Gale is a businessman...

Robyn

01-30-2024, 05:14

More Power

01-30-2024, 15:56

I agree.
But Gale Banks has not been known for peddling "Goody yum yum" parts simply to make $$$$
Gale has always worked to deliver fixes to real problems......

I have never met Gale buy have used some of his parts....Always top shelf stuff

I believe that if Banks thought (or could show that) head studs provided a justifiable benefit, he'd be selling his own - "he is a businessman" after all.

Still... I wish Banks hadn't used a non-Duramax 6600 block deck pic to try to make a point about weak threaded holes in a block deck. That pic wasn't necessary. In my opinion, Banks' opinion/in-house testing is enough to make the point. I trust him.

Studs, however, do have one real advantage over TTY head bolts... Studs are reusable. But... you can buy 3 sets of TTY bolts for the cost of one set of ARP-2000 head studs. This reusable advantage might be important for racers who are inside their engines on a regular basis, but not so much for a grocery getter, commuter, or RV/boat hauler.

As discussed in our Duramax Service Guide, the fire-ring on these head gaskets tend to Brinell (create an impression in the aluminum head decks) over time due to the clamping load of the head fasteners. Both the factory TTY bolts and the ARP studs are torqued to the very same level - 125 ft/lbs. I measured the final torque of the TTY head bolts using a torque wrench during the final TTY angle sweep during installation. And, I installed a set of ARP head studs during another of the Duramax head gasket projects I did a couple of years ago. So... studs aren't being used to add more clamping load, because that would create a deeper fire-ring impression into the aluminum head decks.

More Power

05-14-2024, 12:47

Next month will be three years and nearly 16,000 miles since replacing the head gaskets on my 2001 GMC Duramax 6600.

Here's an update...

There has been no coolant loss or abnormal cooling system pressure. The truck has now experienced three winters since the head gasket project - with winter 22/23 seeing as low as -30 degrees F. Once solving the 10mm coolant hose leak a while back, there have been no engine-related issues. Over the past 3 years, the truck was driven on a few longer trips of a 200-300 miles each, some during the winter and some during the summer.

The truck has set a P0700 code (generic all-encompassing Allison trans code) now and then during this time, and even going back to a year or two before the head gasket work. It comes and goes... The transmission has been serviced twice - replacing the fluid and both filters. The most recent trans service was summer 2021. The root problem with the trans code may be related to a contact issue for one of the pins at the transmission's electrical connector. This has been reported by others on the Internet. The code setting hasn't produced a change in how the engine/trans runs or performs. I'll try to get the problem totally resolved this summer. In the meantime... it's a backburner issue. If anyone can add to this P0700 diagnosis, pls let me know.

DmaxMaverick

05-15-2024, 15:26

More Power

05-16-2024, 10:34

P0700 is only the TCM requesting the PCM to illuminate the SES lamp, which drops the P0700 in the PCM shell DTC. It is not a error or failure, in itself. If the SES lamp is on, and you have a P0700, you need a scanner/reader capable of reading TCM data to recover the causal trouble code(s). Common "code readers" don't do this. Also, the TCM does not clear the P0700. The PCM simply expires it, if there are no further pending TCM codes, after a specific number of warming or starting cycles, depending on the code class. Transient TCM codes tend to clear themselves very quickly, and can leave behind a P0700 ghost. If possible, check the DTC's before shutting down the session it occurred. Some of them clear at the next restart if the condition is not present, and some of them do not print in history. Speed and pressure codes (slippage) remain for several warming cycles, while most solenoid timing, voltage and temperature errors may not last through 2 restarts if they don't repeat. There is also a trigger for limp mode, but I haven't figured out that one yet. I recall seeing a chart of the code classes and reactions, but can't find one now. It may have been in my Alldata account, but I haven't renewed since they priced me out of their market.

Thanks Greg. I had a local friend (and mechanics garage owner) attempt to pull the codes using his commercial Snap-On code reader. He couldn't get any detail beyond the P0700, just like my Predator reader/programmer.

Typically, the SES lamp is off for a few/several seconds after starting the engine, before it reappears. If using the Predator to reset the SES, the lamp will go out for a few/several seconds, before reappearing. I need to crawl under the truck and then wiggle the electrical connector to see if that has an effect. I do know that the SES remained off after the last full service, which I suspect may have been due more to incidental movement of the electrical connector than the service itself. The pan had been dropped during the service to R&R the internal pan filter. There was very little in the way of sludge or particles in the pan and the ATF looked pretty new.

Annotated Allison code list: https://www.thedieselpage.com/members/duramax/allisondtclist.htm

DmaxMaverick

05-16-2024, 12:54

That is curious. If I'm understanding, you are clearing DTC's while running(?) and it reappears in the same session before changing any conditions (such as driving, changing gear selection, restarting)? That is not a transient fault, and it should be, at least, leaving a trail of codes in history. If you aren't seeing limp mode, the P0700 is a soft code, and shouldn't be persistent as it is. Any code that repeats after clearing, in the same session, or a specific number of successive sessions, will print in history. A Snap-On code reader, if that's all it is, shouldn't be able to read TCM codes. They're intended for general ECM DTC's and emissions inspection readiness. I use a Zurich ZR15S, which is a full function bidirectional scanner. It easily reads TCM data and DTC's, as well as historic codes, pending codes (incomplete tests), and all the real time data any of the control modules are capable of showing. A bidirectional scanner may be required to command the TCM to dump it's codes and data, which is true for most other control modules (BCM, ABS, SRS, etc.). I got the scanner primarily to access EV functions and data. GM EV's have a few more control modules that most code readers and many scanners don't know about.

More Power

05-17-2024, 11:43

DmaxMaverick

05-17-2024, 20:04

If a reader/scanner is capable of clearing codes under any condition, it will clear codes engine running or not. Given the opportunity, I will almost always check/clear during the same run session, then try to repeat the conditions before a restart. Some diagnostics only run during a cold start (such as a glow cycle), and/or after a specific number of starts or warming cycles. A high class code in history, even if erroneous, can override clearing the code, and relight the SES. P0700 won't do this, so if it returns, the TCM is still seeing the condition that set it and requests the code and SES. If P0700 is that persistent, there must be an underlying code. You need a bidirectional scanner to clear codes from history, so they should be there. Anyone with a smog inspection in the near future should be careful of this. Clearing history will also reset ALL the smog diagnostics, and restart them from the beginning. It can take days or weeks to get them all to clear. Learned that the hard way.

More Power

07-19-2024, 21:33

https://www.youtube.com/watch?v=20JXJx-luNQ

This video is an introduction to Duramax 6600 diesel service - This video is the first in a series that will eventually show how to do everything listed here, but first, let's talk about what tools, tips and procedures are necessary to complete a fuel injector replacement, cylinder head gasket replacement, water pump replacement and much more.

Can't wait for the video series to be complete? Would you rather have a complete printed Duramax Diesel Service Guide now?
See: https://www.thedieselpage.com/duramaxdieselserviceguide.htm

If you're interested in learning more about Duramax 6600 service and repair, then the introductory YouTube video shown here would be the best place to begin. We've helped thousands of Duramax owners with their own service work through the years. We can help you too.

Our YouTube channel is new, but its growth will help us to provide so much more - at no cost to you.

You can help! Please subscribe to our Youtube channel - run your mouse cursor over the little circle truck image in the upper left of the video shown here. Please Like and Subscribe, and post your comments on YouTube.

I recommend that you create a YouTube account. It's easy and free to register at YouTube.com (http://YouTube.com), plus you'll be eligible for free stuff here in The Diesel Page very soon. By the end of July 2024 we'll begin offering all member-only online content here at TDP (https://www.thedieselpage.com/password.htm) free of charge to those who are subscribed to our YouTube channel. Your YouTube account name will be linked to the free access list.

TDP's long-term goal is to produce more free content videos, some derived from some of the several books we offer. The first book to be transformed into a video will be the "Duramax Service Guide" (https://www.thedieselpage.com/duramaxdieselserviceguide.htm). This book is, in my opinion, the most valuable book we offer. We're very close to uploading the next Service Guide video. The next one will be about Duramax injector replacement and the video after that will be about head gasket replacement - using the same sort of format used here in this introductory video.

Subscribing to TDP's YouTube channel will ensure you don't miss any new videos. As always, your input, suggestions and advice are all important.

More Power

08-09-2024, 10:57

The cooling system in our project truck (Lil Red) was filled with the red/orange colored Dex-Cool coolant back in the spring of 2004. While a little was lost during the head gasket replacement in August of 2021, most of the original fill was saved and re-used. It still looked as fresh as new. Keeping the drained coolant clean is required if anyone wants to re-use it.

Our 2001 GMC Duramax had its head gaskets replaced in the June of 2021. The coolant looked great (like new) and most of it was kept clean and re-used. I could see a lot of the internal areas of the engine's cooling system with the heads off. The internal areas looked practically new. There was no visible indication of corrosion in any of the aluminum, cast-iron, steel or any other component wetted by Dex-Cool coolant.

We used Dex during the September 2021 rebuild completion and install of my daughter's 1994 6.5L Turbo Diesel Chevy Blazer engine. The radiator and heater core were flushed before hand, due to its having used the green coolant from new. The vehicle sat since 2009 till getting the engine running again after the rebuild. In the years since 2021 and getting the Blazer back on the road, there have been no coolant related problems (or problems otherwise).

Conclusion... Dex-Cool is a great!

Upcoming will be a new video showing the Duramax engines during the disassembly/re-assembly process of having their head gaskets replaced. You'll get to see inside both engines. The Youtube video should be available sometime near the end of this September. I'll announce it here when it goes live and you'll be notified by YouTube if you're subscribed to our channel. :) Jim

More Power

08-14-2024, 01:27

https://www.youtube.com/watch?v=QQ1D1FUk1zs

Duramax Diesel How-To video series! This video will show you how to correctly remove and replace the LB7 Duramax 6600 diesel fuel injectors. This video is part of a series of service videos (available now and upcoming), all designed to help you perform your own service work, save money and get a better result.

To learn more about the "Tools, Tips and Supplies" you'll need when working on your Duramax 6600, watch this video first:
https://www.youtube.com/watch?v=20JXJx-luNQ&t=2s

Can't wait for the video series to be complete? Would you rather have a complete printed Duramax Diesel Service Guide now?
See: https://www.thedieselpage.com/duramaxdieselserviceguide.htm

If you're interested in learning more about Duramax 6600 service and repair, this series will be a big help to you. The Diesel Page has helped thousands of Duramax owners with their own service work through the years. We can help you too.

Our YouTube channel is new, but its growth will help us to provide so much more.

You can help! Please subscribe to our Youtube channel - run your mouse cursor over the little circle truck image in the upper left of the video shown here. Please Like and Subscribe, and post your comments on YouTube or here.

Subscribing to TDP's YouTube channel will ensure you don't miss any new videos. As always, your input, suggestions and advice are all important.

Want to share this thread with others or help us get the word out about LB7 Duramax Head gasket and Fuel Injector Replacement? It's easy! Simply copy the following link and paste it into another forum post, email message or social media site:

https://www.thedieselpageforums.com/tdpforum/showthread.php?46717