View Full Version : Things were just a little too cozy...
Pulled the heads from my old engine this weekend and found a disturbing sight -
http://www.thedieselpageforums.com/tdpforum/[img]http://i.imgur.com/njQWZcz.jpghttp://www.thedieselpageforums.com/tdpforum/[img]http://i.imgur.com/njQWZcz.jpghttp://i.imgur.com/njQWZcz.jpg?1
This was a low-miles stock engine when I purchased it. I pulled the heads at that time to inspect the cylinders and all looked good. I reinstalled heads with FelPro gaskets and ARP studs. The only other modification to the engine was a DSG gear drive.
This wasn't the only cylinder. Several others showed imprints of the intake valve in the carbon on top of this piston. This one is the worst though as there is an actual indentation in the top of the piston from the exhaust valve.
I think I found the reason this engine always sounded mechanically noisy.
The more I look at things, the more I come to the conclusion that there must be a problem with the cam timing from the gear drive. Has anyone taken the time to degree a cam after installing a gear drive to verify that these things are accurate?
How far out of the cylinder is the piston protruding ???
You bought this engine used ??
Was it a rebuild ???
If so, by who, and were the decks cut ???
Almost looks like that piston is above the deck some ???
When you had the heads off did you use a standard head gasket ???
Specs say the piston should be even with the deck to NO more than .005 above the deck at TDC
The decks can be machined .010" butttttttttttttt I have taken them to .015" in a pinch to get a good clean surface.
The thicker (.010") gasket must be used when the decks have been cut.
These engines are really really tight inside even from the factory.
I am thinking that the gear drive would need to be waaaaaaaaaaaaaaaaaaaaaay off to cause this type of issue.
The stock timing chains can and do get pretty loose over time (Causing some valve timing changes) and there are no issues with valves smacking the pistons.
The cam profile on these engines is pretty mundane and should not even be an issue.
How many pistons show valve contact??
More info please:):)
How far out of the cylinder is the piston protruding ??? Haven't measured yet but they appear flush. This was just a rough check using a straightedge across the deck.
You bought this engine used ?? Yes
Was it a rebuild ??? No, it was supposed to be a low mileage used engine. When I pulled the heads and main caps the lack of wear supported this assumption.
If so, by who, and were the decks cut ??? N/A
Almost looks like that piston is above the deck some ??? Actually that picture the piston is down in the hole.
When you had the heads off did you use a standard head gasket ??? Yes, Felpro standard thickness.
Specs say the piston should be even with the deck to NO more than .005 above the deck at TDC
The decks can be machined .010" butttttttttttttt I have taken them to .015" in a pinch to get a good clean surface.
The thicker (.010") gasket must be used when the decks have been cut.
These engines are really really tight inside even from the factory.
I am thinking that the gear drive would need to be waaaaaaaaaaaaaaaaaaaaaay off to cause this type of issue. I'm going to do some measuring before I take it the rest of the way apart. I know what the factory lobe center should be with a stock chain so I can compare to that.
The stock timing chains can and do get pretty loose over time (Causing some valve timing changes) and there are no issues with valves smacking the pistons. Yes, but that retards the cam. There may be an issue with advanced cam timing.
The cam profile on these engines is pretty mundane and should not even be an issue. It is mundane but these are an interference engine. There isn't enough room for the valve to be all the way open and the piston to be at the top of the stroke.
How many pistons show valve contact?? I only have the passenger head off so far and it only looks like 1 exhaust had firm contact hard enough to cause an indentation in the piston. 3 of the intakes have left impressions in the carbon but don't look like they actually made metal to metal contact.
More info please:):)I will share more as I continue to investigate. I wish I could find the notes I made about what holes I pulled the bent pushrods out of when I took the top end apart a couple years ago.
arveetek
07-07-2017, 06:35
I wish I could find the notes I made about what holes I pulled the bent pushrods out of when I took the top end apart a couple years ago.
Sounds like this engine has had this problem for a while then. Valves hitting a piston will definitely cause bent pushrods.
Casey
Got the engine pulled and got the other head off. Amazingly none of those pistons showed any signs of valve contact. Next need to finish disassembly so I can send the rods over to the machine shop for resize and the crank so everything can get balanced. While it is apart I'm going to match-port the intake and exhaust. I'm putting in a new set of valves and I'll have the machine shop cut the minimum go get the heads flat.
But before I pull it apart, I'm going to do some measuring to see if I can find that side had the issue.
Sounds like this engine has had this problem for a while then. Valves hitting a piston will definitely cause bent pushrods.
Casey
Yeah, it was noisy when I first installed it. I pulled it apart about 5 years ago to have the injection pump rebuilt and was going to swap out the lifters because I thought I had a bad lifter. It has been sitting ever since.
Just noticed something also over the weekend. All of the pistons are marked with their location. You can see the "2" in the center of that piston. Is that normal on a factory engine?
john8662
07-29-2017, 20:32
That engine has been rebuilt. Those are Mahle pistons and look to be .040" oversize by the 100 marking.
This will require a dial gauge and bridge to see what the piston height is at TDC.
Maybe it had .010 thicker gaskets on it previously.
Since both valves are hitting, it's either a piston protrusion problem or incorrect valve depth and install height (machine shop can verify this), also uses dial gauge and bridge.
Will certainly be interesting to see wasssssup on that one side.
My bet is the deck was cut.
Check along the ledge at the top of the block to see if anything was stamped there to indicate that a cut was done on the deck.
To step back some ... If the cam timing was off then both sides would have had valve to piston interference issues ????
Very interesting situation... Very curious to see what you find.
Robyn
Other side showed no signs of hitting at all.
Is there something I can measure on the head to see how much the heads have been shaved?
No markings on the block or deck at all.
I'm seriously pissed at the company that sold me the engine. Now I have to question the integrity of the rest of the internals. Questions such as did they do something stupid like grind the crank?
The main concern is the piston top to deck dimension with piston at TDC.
If the head/s have been cut they are not as tough ($$$$) to replace.
You can use a depth mic and check the distance between the face of the valve/s and the face of the head. (Use a ground bar to span the chamber and place the mic on the bar)
My bet is still that the deck on the one side was cut.
These can be cut .010" and I have personally gone to .015 to save a block, but any cut of substance requires the use of the thicker gasket.
Very common to see the area around the front two cylinders gasket fire ring eroded into the block.
Without cutting the deck the gasket will fail again.
If after a thorough cleaning there is any indent into the deck where the fire ring sits the deck must be machined.
Felpro makes the new gaskets with a stainless block off for the front two water passages.
This stops the coolant from laying against the bare block and causing corrosion that results in the gasket failure.
Using premixed coolant (green) is much better than the concentrate as the "local" water can be all over the map as far as it's PH and mineral content.
Keeping the coolant readings proper helps a lot to stop issues.
(Use the little dip sticks with color chart)
May well be a combination of a head that's been cut as well as the block.
Check your piston protrusion as well as the valve face to surface on both sides.
Get all the numbers and it should ferret out what happened.
Good luck and keep us in the loop
Well the info on the oversize pistons confirming this was a rebuild made me go back out to the garage and really search the block for any markings. Sure enough, on the back of the block on that side (had to remove the layers of paint to read it) I found "SUR007". There was so much paint over it that you could not make out that it was a stamping - I only saw it when I put a light across it sideways. Once the paint was off it was very clear. Assuming that means they took 007 off that side. No markings on the other side. No markings on either head indicating that they had been machined but I would still like to know what the spec is for how deep the valve should be in relation to the deck. I just ordered a bridge for my dial indicator.
Interesting looking at the bores again...nice crosshatch still but you can really tell that it wasn't bored with a torque plate.
Using premixed coolant (green) is much better than the concentrate as the "local" water can be all over the map as far as it's PH and mineral content.
My dad taught me at a very early age that the only 2 things you ever put into a radiator are coolant and distilled water. I still follow that rule. I always keep a couple gallons of distilled on hand for radiators and batteries.
Daddy was spot on.:):)
Getting reliable info on the valve depth may be difficult at best.
Check your other side and see what the differences are between the two.
IF they scalped .007 off the deck and the head was cut too, that would explain the issue.
Likely a .010 thicker gasket would fix the interference issue, but things need to be right.
Years ago I had a 6.5 that cracked the #3 main web in the oil squirt hole and it went up into a cylinder until it hit water :eek:
I bought a "Guaranteed" CRACK FREE block from a rebuilder's service company.
Block was bare.
Cleaned it, magged it and then bored it for .020" pistons.
The decks were a bit sketchy so decided to surface them.
All good ..... Ahhhhhhhhh, noooooooooooooooo.
Started assembly and discovered the #2 piston hanging out of the hole .030"
:eek::mad::eek:
LEFT SIDE had been hit before, so ended up with big issues.
No marks on anything.
Ended up using a custom made MLS gasket BY Cometic (Bad jump)
These are nice gaskets, but not for the 6.5 (not enough head bolts)
The engine ran great for a year until the gasket failed.
These engines need the composition gaskets to live.
Ended up digging up a NEW AMG block.
Long convoluted story of some very interesting happenings at AMG, Navistar and it's employess.
But I ended up with a great engine in the end.
So many things go on out there in the re building game that it can drive ya nuts.
As far as Torque plates go, not many floating about in the hands of most shops for these engines.
With .004" PISTON clearance they seem to do OK
There may be plates made now, but in years past it would have had to have been custom made inhouse.
Sounds like you are gaining on it :):)
Robyn
As far as Torque plates go, not many floating about in the hands of most shops for these engines.
I own one. :D
DmaxMaverick
08-01-2017, 15:15
I own one. :D
I remember that post, and pics. Very useful tool, especially with what you have now. Very accurate for measuring absolute piston decking and valve recess. More accurate than a bridge and dial.
Sweeeeeet
Getting the cylinders nice and round is dependent on using a plate.
The final torque on the deck can and does change the shape of the bores.
:):)
Finally getting back to my project here...too many house projects keeping me away from mechanical stuff.
Got the block completely stripped last night so I could get the rods and crank over to the machine shop today. My how 15 years of knowledge makes you notice things that you haven't seen before.
I purchased the engine back in 2003 or 2004 and pulled the pan and installed a set of DSG girdles. When I pulled it apart I realized that I had smaller outer bolts on the mains. That didn't make sense since this was supposed to be a 1997 block, which should have the bigger bolts. I must have just thought I scored a later block when I installed the girdles. Remember this was supposed to be a "low mileage stock engine" that was sourced from a diesel engine supplier.
After I removed the girdles, I noticed that the outer bolt holes in the caps were large. Hmm... I pulled the main caps and what do you know, inserts in each of the outer holes. Well, why would they have gone through all that trouble with the rebuild? Yep, because the block was cracked. Web between 1 & 3. Extended about 2" up the front of the web and a little shorter on the back of the web.
Hindsight being 20/20, buying a rebuildable core would have put me far ahead in terms of cost and reliability. A "great deal" on a "low mileage" engine sounded good at the time.
I already had plans to scrap the block, so really nothing more lost by finding the crack. Just makes me want to punch the idiot that sold it to me.
Hi,
Years ago I dropped a valve on my 6.2 non turbo Jimmy Blazer.
Shut it down almost at once, and got away with nothing more than a nice circular imprint in the carbon on the piston. No further damage evident, and it ran well for years afterward.
FWIW.
Jeep
There are a lot of cracked blocks out there.
With the inserts in the holes the block should be good to go.
Are these the LOCK N STITCH ????
THEY WILL hold things together.
As long as the crack is not past the end of the web area you should be OK.
When the crack gets into the area beyond the bolt holes its getting real sketchy..
Beyond the bolt holes and they can start into the cylinder wall, and this is a no no...
More Power
03-16-2018, 09:22
The shadowed imprint of "both" valves on the piston crown tell me that piston protrusion exceeds the allowable high limit. I doubt it's a valve timing issue. With a valve timing problem, I'd be inclined to think that one valve or the other could have an interference problem, but not likely both.
Incidentally, I wrote an article covering 6.5 piston protrusion a while back...
https://www.thedieselpage.com/members/features/protrusionc.htm
Well if anyone wants an early squirter block, .040 over, 007 taken off the decks and has a cracked main web, please come get it. Otherwise it is heading for the scrap heap.
Block with inserts visible -
https://i.imgur.com/29CylMn.jpg?1
Pulled my heads apart and found aftermarket seals on both intake and exhaust. No o-rings on the stems.
Machinist recommended going to a modern viton seal instead of the rubber that were on there.
Would I still need o-rings? Since mine did not have o-rings (and definite oil control problems) I have no reference as to where they would be installed (over or under the seal).
Thanks!!
sctrailrider
03-17-2018, 16:44
The o-ring goes in the lower top grove on the stem not down where the seal is... and yes I would say you need it..
The o ring helps keep a lot of oil from pouring down from the spring retainer past the keeper and down the valve stem.
Yes you do want the o rings in there.
Good luck
Well that explains why there was so much oil residue in my intake ports...
DmaxMaverick
03-19-2018, 10:18
Well that explains why there was so much oil residue in my intake ports...
There is so much oil vapor/residue allowed by the CDR, I doubt you could really tell how much would be allowed by the valve stems. The O-rings are necessary, but hardly negligible compared to other sources.
There is so much oil vapor/residue allowed by the CDR, I doubt you could really tell how much would be allowed by the valve stems. The O-rings are necessary, but hardly negligible compared to other sources.
That would be true if my CDR had been routed to my intake, which it was not. And all of the residue was in the pocket behind the valves, not upstream of the guides.
sctrailrider
03-19-2018, 14:21
Then your guides were wore out...
More Power
03-19-2018, 15:07
Ordinarily.... There is a positive pressure inside the valve runners in the cylinder heads for both the intake and exhaust. The turbocharger is pressurizing the intake and exhaust back-pressure is usually positive because of the restrictions to flow (catalytic converters/mufflers/pipe/etc).
So... Oil doesn't want to seep past the valve stem seals all that much. Some does, but not much. A 6.5 that uses too much oil usually has more problems than just bad stem seals.
Where is your CDR routed to ????
The CDR when things are correctly working is supposed to pull a slight negative pressure in the crankcase.
This keeps the main seals from leaking as well as keeps oil from drizzling down the valve guides (At least in large quantity)
Is this engine turbo'd ???
A leaking turbo bearing that's allowing oil into the air stream will sure cause issues.
If there is no connection to the slight negative pressure in the intake airflow then the crankcase is running a positive pressure...not good.
This engine had all kinds of issues... LOL. That is one of the reasons I decided to pull it. It always used a lot of oil and had a lot of blow-by. The seals I pulled off were hard - not pliable at all. I know the guides were out of spec just by how much wiggle the valves had when I disassembled the heads.
Yes, engine was turbo'd. There are zero signs that the turbo was leaking any oil.
CDR was simply routed down under the frame with a filter on it. There was way too much blow-by so I never had it on the intake.
Got a call from the machine shop. Both heads had been welded around center head bolt holes. That much I could probably live with, but when they measured them they found both had already been machined past minimum thickness, one of them being .028 under. :eek:
No wonder this engine had issues.
Set of Promaxx replacements on the way. $255 ea with free shipping from Jegs for a set of bare heads.
These sort of engine jobs are out there, and the 6.5 is critical on the head dims and other things too.
I am not familiar with the heads you mentioned... CHINA castings ????
I have used the Clearwater "NEW" heads and the ones I had worked fine.
The ones from AMG are the best choice... if the budget can stand it.
Welding on these heads is a disaster waiting to unfold.
Good luck
Well after reading some real world experience with the Promaxx stuff, I cancelled the order. I ended up grabbing a couple used heads with a 6 month warranty off Ebay and will have my guy work those instead. The Promaxx are China. Issues with casting shift and they use a steel (magnetic) pre-cup and the holes are too big for factory pre-cups. I wish I had an extra $1800 in the budget for a set of new AMG, but...
So...Robyn...how are you liking those Clearwater heads? Heads I got were cracked and seller could not come up with another set that weren't cracked, even after pulling off of "running" engines, so I got a full refund from him.
Did the Clearwater have good pre-cups? One issue with the Promaxx was that their cups were magnetic and they were slightly larger than a stock cup so stock cups wouldn't stay in place.
The Clearwater heads worked fine.
The cups were magnetic...
The fact that they magnetic is a moot point me thinks...could be stainless steel (some grades are magnetic)
I have no clue, but it was not a deal breaker..
I checked them over for anything unusual and then dropped them on. (Make sure the cups are slightly above the head surface .0005" to .002"
The engine ran good and we put over 50K miles on the rig after the O'Haul
I sold the Burb and I saw it a year or so later and the fella said it was running great.
They are not as good s a set of AMG heads, but far less $$$$.
I good part is that they are ZERO hour parts with zero duty cycles and have not been overheated or run at 20 PSI boost or ???? whatever other form of torture some clown can dish out.
Thank you for the feedback. Seeing as how uncracked GM heads seem to be like hens teeth, I'm looking at alternatives. Feedback on the CW heads seems to be good so far from what I have found on google. I would like to find someone that ran a set for a while then pulled them to find out if they cracked between the seats also. I could interpret the fact that no one has pulled off a set as a good sign.
Another point to ponder would be to get your hands on a set of well used AMG heads and give them a really good going over to see wasssssup.
I have a feeling that the best solution is to grab a set of new brand X heads, bolt them on and just run them..
The flawed GM heads would generally go 200K miles give or take.
Some cracked early, some ran far longer.
The type of usage the rig was subjected to certainly could change the life expectancy, but overall the 200K mark is a common jumping off spot for the gaskets to fail.
I had 2 used Burbs and the Dahoooley and these numbers were pretty close.
One Burb went 237 K ...The other went 267 K and the Dahoooley was a crap shoot as the engine had been changed to a Goodwrench and the bottom end failed (Main web cracked into the water jacket)
Gawd only knows what the real lowdown is on these after market heads, but the various brands seem to be staying around.
Clearwater has been in the game a long time now.
I spoke with AMG about the various parts (blocks/heads) that are on the market, and they told me that they have looked the stuff over well.
The only issues they had were that the consistency of quality was all over the map... being ...some good ..some bad and some ugly...
I wish I had more info for ya..
Good luck
ronniejoe
05-17-2018, 09:19
and have not been overheated or run at 20 PSI boost or ???? whatever other form of torture some clown can dish out.
Gee, I wondered why my nose was big and red...:D
ronniejoe
05-17-2018, 09:20
I dropped $2100 last fall for a set of P400 heads.
I dropped $2100 last fall for a set of P400 heads.
If nothing else had gone wrong with this, then I might be able to do that. Right now that isn't in the budget.
I hate to brag...but the heads I got for Dahooooley were the normal pickup arranged P400 heads that were installed on a P400 that was ordered for a civvy H1 by mistake..
AMG sent the fella a fresh set of the proper angled bolt heads with gaskets and bolts and told him to keep the pickup style heads.
Got them suckers with zero hrs for $600 for the pair..:)
Another set of "guaranteed" good used heads with cracks in all 8 chambers, with many cracks going through the intake and exhaust valve seats.
https://i.imgur.com/GRxOJPKb.jpg
DmaxMaverick
05-23-2018, 10:53
Seems like you just can't catch a break! A world I'm all too familiar with.
More Power
05-23-2018, 11:29
Another set of "guaranteed" good used heads with cracks in all 8 chambers, with many cracks going through the intake and exhaust valve seats.
https://i.imgur.com/GRxOJPKb.jpg
Tough break... I too have a set of heads that I bought with the assurance that they were crack-free. I found at least one crack between the valves so far. They'll need to be thoroughly checked out by the engine shop.
With what it costs to ship these heavy items anywhere, I have begun recommending people ask that the heavy part they're considering be QC checked by an engine shop before dropping any bills on it. That'll be cheaper than dealing with all the shipping costs.
Tough break... I too have a set of heads that I bought with the assurance that they were crack-free. I found at least one crack between the valves so far. They'll need to be thoroughly checked out by the engine shop.
With what it costs to ship these heavy items anywhere, I have begun recommending people ask that the heavy part they're considering be QC checked by an engine shop before dropping any bills on it. That'll be cheaper than dealing with all the shipping costs.
So far the shippers have been eating the costs. I would think that they would test them before selling them. I'm sure they are betting on someone receiving the head and bolting it on and running it, and not actually crack checking them.
JUST AN FYI :)
Get a set of the Clearwater heads, bolt them on and enjoy...
I went through several sets of heads back in the days of the Dahooooley and the used stuff was just junk.
Out of 4 sets of heads I got ZERO good ones.
The last trip through, that rig got an AMG BLOCK and AMG heads.
The CW heads went on the Burb...
Someone recommended the heads from SS Diesel because they are supposedly USA castings. However SS couldn't tell me if they had hardened seats or inserts. I'm just leery of the steel pre-cups in the Chinese heads. SS also said his had steel cups, which are superior to the factory stainless steel cups and people should quit reading what people write on the internet about the steel cups.
The Heads I bought were ordered right from Clearwater.
I stayed away from all the second and third party sellers.
I tried sorting through all the hype on who's heads have what casting, made in what third world country, shipped to the US for machining, and using which original GM parts, that were remanufactured in what dumpy shop in Chicago ????
The stories are so convoluted and embellished with BS that's laid on with a trowel it's impossible to ever find the real truth.
I spent over an hour on the phone with a fella at AMG after I scored the AMG block with the mainline that was .0025 too small, and we covered the entire story on the after market parts that are out there.
The folks at AMG certainly have the ability to separate the fly chit from the pepper and they are even at a loss as to who has what, made by who and with what parts...
As I mentioned before, the Clearwater heads served me well...
I have no doubt that they are not as good as the AMG parts, buttttttttttt, when $$$$$$ are a big factor the CW heads are not a bad choice.
Trying to make a well educated choice on this subject will drive ya crazy...
Good luck
Trying to make a well educated choice on this subject will drive ya crazy...
Amen. I have spent too many hours researching this. Latest seller finally agreed this morning to refund all of my money and doesn't want them back. So now I have 3 set of heads lying around.
Interesting that I had a chat with Odessa regarding their rebuilt GM heads and asked them what they did about the cracks. He came right back and said they pin them all. Maybe when this is all said and done and I have some extra time, I'll call up the folks at Lock-N-Stitch and have a go at repairing a set of these and see how they turn out.
FWIW
I personally would not waste one thin dime on a set of well used GM 6.5 heads
Besides cracking they have coolant flow issues internally (likely causes the cracks) and once you have a crack, getting it to stay pressure tight is going to be a crap shoot.
Even a pinhole leak into the coolant passage will/can cause overheating, coolant loss.
The lower end cracks can be arrested and stabilized as they do not allow and real issues, unless the breach the oil passage and allow pressure loss, or travel up into the lower cylinder area and into the water jacket..
The best use for an old set of 6.5 heads is using them as door stops...or maybe a boat anchor...
Back in the dark ages I fooled with the 5.7 Olds diesels...
The cars could be purchased CHEAP once the Diesel started giving issues.
I had a 79 Calais that was a sweet heart... but would over heat and blow the water out....sound familiar :rolleyes:
I got real good at getting the heads off these rigs fast.
I finally found the issue on that rig... One cylinder had a tiny pinhole that was leaking, and the shops only mag'd the heads (no pressure test)
I built caps for the coolant passages and aired the heads up.
found the pin hole....
Decided to drill it out and thread the hole for a pipe plug.
Plugged it and then peened the hole well to prevent the plug coming out ;)
The spot was on the fire deck so was easy to deal with.
That thing ran for many years that way..
Glad you got your $$$$ back...
More Power
05-25-2018, 09:05
Based solely on my own personal experience with crack-repaired OE cyl heads, I don't have a problem with them. I have extensive experience with "crack between the valves" repaired cyl heads (>300K miles). A cracked block on the other hand scares me too much to consider investing any money in one - considering how much quality machining costs these days.
ronniejoe
05-25-2018, 09:13
Those repair kits from K-Line to sleeve the drilled passage between the valves that you wrote an article about years ago are not available any more -- I checked last fall.
The concern I have with the cracks between the valves is progression through the seat. There is no way that it won't eventually leak compression.
I've had some good luck with repaired heads that were furnace welded to repair cracks. The problem is, the source that I used has quit doing the repair. They've gotten into marketing their own aftermarket race heads and don't want to do repair work anymore. I can't find anyone else who will do it.
I have one of the K-Line kits with enough liners left to do 3 more heads.
Seeing as how every head I have checked so far has been cracked across a seat, the repair would be...
- Pin the crack from one end to the other using Lock-n-stitch pins. That would potentially start in the intake port, up through the valve seat, across the chamber, through the exhaust valve seat and into the exhaust port. Not all were that bad, but of the 6 heads that were crack-checked by my machine shop, every head had at least one crack that went through a valve seat.
- Install hardened seats on the intake and exhaust
- Install the Kline liners
I'm hoping that a head that has hardened inserts installed in the exhaust and has not been induction hardened will not have a cracking issue.
So far I have found 2 suppliers (SS Diesel being one of them) that claim their castings are US and that have hardened inserts. SS is more expensive, but the other supplier doesn't appear to have rotators installed on the exhaust valves. That is an easy fix though.
More Power
05-25-2018, 13:19
The sleeves are standard size valve guide liners. So, any decent head shop will already have the reamers and liners. Don't need the kit. The engine shop here in Montana that has done these for me in the past didn't use a kit.
Cracks of any kind - found in either a head or block - always come with a fear of progression. I have enough miles of trouble-free experience with crack repaired heads to know that there are more important things to worry about.
The repaired cracks I've seen in heads that had been torn down for other reason were filled with compacted carbon in the seat. Compared to piston ring leakage? Anything with a crack is not perfect. Myself included. Perfection remains a goal.
Those repair kits from K-Line to sleeve the drilled passage between the valves that you wrote an article about years ago are not available any more -- I checked last fall.
The concern I have with the cracks between the valves is progression through the seat. There is no way that it won't eventually leak compression.
I've had some good luck with repaired heads that were furnace welded to repair cracks. The problem is, the source that I used has quit doing the repair. They've gotten into marketing their own aftermarket race heads and don't want to do repair work anymore. I can't find anyone else who will do it.
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