It's my turn, Now the front of the truck is lighter...

[john8662]

Well, I finally did it, I found a way to make the front of the truck lighter and make it a whole lot quieter.

My '86 truck is officially off the road, while I repair or rebuild the engine, I removed the engine.

This engine has been troublesome in that it idles very poorly and has a nice ticking sound when the engine is under load. Many of you have followed some repair tactics that I've undergone, from installing a new IP, injectors, timing gear set, stud girdle, etc.

That can be followed here (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=2;t=003410)

Also, the last repair I did to the engine was to troubleshoot a rapping noise that would occur when the engine hadn't been started in weeks. I had figured it was a lifter because when it had run for about 2 minutes the noise quit completly, so the lifter pumped up. So I elected to replace the set of lifters with the engine in the vehicle and with the heads installed. I did find 2 bad lifters in the process. I installed a complete set of Melling lifters and within a two week span I had a different problem but lifter related the engine started ticking bad, I had to pull those lifters to find that HALF were not pumped up and were bad. The symptoms were really rough running, low power and ticking at anything above idle. A post covering this was here:

failed lifter noise for those that know.. (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=2;t=003535)

The next set of lifters I installed (engine installed still) were under the name of SBI, and they are still in the engine. Since I am still getting a ticking noise (but not near as bad as the Melling were) I figured I'd just pull the engine to get a better look, since I cannot endure replacing lifters in the engine with it installed and the heads on again. Besides, what if i wasn't lifters this time? It's a LOT of work, and it's tedious anyways!

So, here we are, trying to figure out the mysteries behind this 150k engine.

Here are a few basic pics of the removal

Last chance, what do you want on your tombstone? (I talk to my truck)

http://members.cox.net/acmdsl/www/truck/rebuild/images/01-512.jpg

Where did it go, it says "6.2 Litre Diesel" on the fender, but where's it at?

http://members.cox.net/acmdsl/www/truck/rebuild/images/03-512.jpg

And now, it's current new home, sittin' on the new orange engine stand.

http://members.cox.net/acmdsl/www/truck/rebuild/images/05-512.jpg

And finally, it's current state, somewhat stripped down, and I already removed the valve covers to take a peek

http://members.cox.net/acmdsl/www/truck/rebuild/images/08-512.jpg

So, I pulled the engine because I didn't want to do the third lifter R&R in vehicle because I just KNEW it was another case of lifters that were not getting enough oil to pump up or the clearance in the valve train was out of tolerance, or defective lifters (seems to be the trend). Well, I found a few things that justified pulling the engine.

When pulling the engine I disconnected the torque convertor to flexplate bolts. To my surprise I only have three main bolts, and this is especially surprising because this is the original tranny. Anyways, I removed two of the bolts and continued to manually rotate the engine from underneath to get that third bolt out. When I got to it I noticed that the TC was loose in it's connection to the flexplate. The bolt wasn't loose though (hard to turn). I was able to remove the bolt to find that the threads on the bolt were burred and stripped. When I got the engine out I was able to look closer at a problem. The Flexplate is now junk, the hole where the bolt goes has a washer like cunk missing where the TC contacted the plate. The TC is now junk because the friction between the plate being loose and TC being loose messed up the mounting pad (so it's now uneven with the other pads) and the obvious messed up threads. Hmm, glad I found this little unknown out, now I think I may be able to solve one problem.

The loose TC to flexplate problem is probably what has given me the groaning sound in the cab at 1700-1800 RPM under load that I NEVER could troubleshoot. I replaced engine mounts, tranny mounts, harmonic balancer, belts, crank pulley, etc trying to get it to stop. I'm pretty sure this has been the problem to that all along. The bad... I need a new TC and flexplate for a tranny that probably doesn't have anything more to offer, I think it's probably running on "borrowed time".

Finally, since I got the engine pulled and on the stand it was MUCH easier to work on, so I pulled the valve covers and took a look. I didn't find what I thought I would find (lifters that had bled down as before). ALL 16 lifters appear to be holding prime, I've rotated the engine over many many times placing each cylinder at TDC to verify this. I was surprised, but I still get to dig further.

So, my lifter assumption. The first set of replacement lifters were Melling, and were of a different design (in appearance) than of the factory and SBI lifters. THE MELLING LIFTERS SUCK! No other way to put it, I'm standing by this for the moment, that no one should even consider Melling for anything valve train (oil pumps are a different story).

I'll post pics of them later, and have more information as I have time to find it out, I should get some time to take the heads off on Sunday and see what else is the matter. Going to be pouring Concrete Saturday...

[arveetek]

Good luck, John!

As you well know, I've just been down the same road with my engine rebuild. I can tell you, there were many times I got very discouraged and was ready to throw in the towel, and I know you will too. (I read your post in the member's forum...trust me...you don't want a Ford! Take this advice from a Ford owner....) But hang in there, and it will all soon come to pass.

Casey

[john8662]

Casey,

Thanks, I learned some valuable lessons through your build that will hopefully save me some grief. Like, getting the pistons BEFORE having my local machine shop bore the block. And.. you caught me on the members forum :rolleyes: ... I'm fixing my 6.2 and 6.5 and not buying anything new.

The project:

Well I couldn't wait to get out to the shop and take some more stuff apart, I'm really tired from the days work, but curiousity got the better of me.

Here is the quick info I found so far.

Passenger's side head has the cracks on two cylinders between the valves, on holes #8 and #2. A couple of the pre combustion cups are no good on a few holes, cracked all the way past the sealing ring on the gasket. The cylinder bores on the passenger's side look excellent as far as wear, still cross hatching on the walls, and so very very little ridge ring.

On the other side, the head is fine (so far), but has one pre cup that is completly toast, cracked past the sealing ring on the gasket, first time i've seen them crack like that.

The bad about the heads, being an 86 i thought I'd be immune to the extra cooling port (bean shaped port) being in the heads, nope mine have em. But... These heads have the BIG valves, no wonder this truck was a tire spinning little trouble maker, this engine has been the most powerfull 6.2 n/a engine I've ever driven.

Another bad so far, and I figured I'd run into it anyways, Cylinder #1 has way more wear than any of the other cylinders, not sure why, but it has a definite ridge ring completly around the cylinder. So, I'll be doing the whole thing.

More to come, took the pan off, still no cracks on the bottom end but I didn't go any further tonight, tomorrow the crank and pistons come out and I will remove the cam and look at it (I suspect I have problems here, either bearings or worn cam).

[john8662]

Well... It's all in pieces now, I have completly disassembled the entire engine. No cracks that I can find anywhere.

So far my findings..

Two of the cam bearings are rough, none of them look like they're spun though.

The first main bearing is significantly more worn than any of the other bearings, and I don't know why, worn through the first layer.

All the rod bearings looked great, and I've kept all these bearings in order and place just in case I find some of of the odd sized ones.

I don't have any plastigauge, but that would have been a good idea, I can still do that for the mains. I also need to measure the cam and crank journals.

So far I'm glad I tore the engine completly down, it was ready in many ways I'm afraid.

The heads seem to be the worst part of the engine, and I'm a little concerned about whether they're going to be rebuildable. One thing that really bothers me is a white hard crust that's developed under the intake valves on two cylinders. To me it looks like antifreeze, I also wouldn't think that there would be any buildup on an intake valve, it should be clean!

Here is a pic of the worst valve (before cleanup, just as unbolted)

http://members.cox.net/acmdsl/www/truck/rebuild/images/headno1.jpg

it looks white now that I've cleaned the head surface to look for cracks and sprayed it down with brake parts cleaner.

[arveetek]

The '86 heads I used on my rebuild also had the extra cooling port, as did the '82 and '83 heads I tried to salvage. Apparently is was after '86 when GM eliminated that port. I wouldn't be surprised if it was around '88, when some other changes took place.

I definitely believe that the GM diesel heads are the weakest link in the system. I had to find a third set of heads that were even useable, but they still needed a lot of work. As a result, I have two extra good blocks laying here in the shop. However, it's looking like I might end up using one to rebuild to install into my Dad's '82 Ford F250 that just blew a 400 gasser. Why not? :D He's got a good old work truck that needs an engine, and I have a lot of spare 6.2L parts. I think I have enough good parts to make a decent running work truck engine.

Are you going to bore the engine, or do you think # 1 might clean up?

Good luck with your rebuild, John.

Casey

[john8662]

Casey,

It's been awhile before I could update this post.

Thanks for confirming the head condition! I was starting to think that I had more of a mess up than I already do.

I got a chance to measure all 8 cylinders, turns out that #2 was actually larger than #1 was, just the cylidners on the drivers side actualy developed a ridge at the top of the bores, where as the passengers side doesn't have any cut ring in the bore.

The measurement on #2 was biggest on my vertical measurement among all the cylinders which came up to 3.9860" so it's out of spec for stock pistons for sure because it doesn't fall in the 3.9758" - 3.9789" stock piston range.

The good news is that I can easily get away with a .020' overbore because that has the range of 3.9960 - 3.9999 (according to specs I got from Benny).

I'm going to buy the pistons coated from Avant as well as the ring set, just had to make sure that I was in the range. When I get the pistons in hand, then I can take the block and pistons down to my local machine shop and have the block bored.

I'm thinking for now to go with the stock compression ratio, as this truck will no longer have any duties pulling trailers, but no with an ATS turbo for a little more grunt (it had power in stock form). The sole purpose of the truck will be to haul the 4wheeler to the dirt track and me of course.

Whats your impression of the dropped compression? I was informed I could go with a shaved .010 piston to drop it a point. So it could be 20.75:1 instead of the 21.75:1 C/R. That is, if I don't deck the block or mill the heads (which I don't wanna do).

Besides engine block work, I've been working on other things on the truck, like completly removing the evap box from the firewall to re-seal it (air noise in cab). Which this was started because I needed to replace the heater core (which is normally a complete pain in the butt) it was still a pain, but a little less so w/o dealing with the engine in the way. I also cut my exhaust system out from underneath the truck Sunday Night, now I guess I'm comitted to install a turbo huh. I really hated to ruin the perfect duals I've become so fond of (factory V'ed out exhaust). Oh well, it's not like the truck is stock anymore.

I'll update as soon as I know more...

So, a 6.2 in a F*rd, sounds like a good idea to me! I'm like you, I've got enough parts engines to make a runner (didn't say a good runner).

Got a complete '87 engine (picked up for 50 bucks complete with all accessories), supposed to run, I want to set it up on a stand and test run it for grins. And a a 91 shortblock that needs rings, and an 85 model 6.2 that I pulled with a rod knock, never pulled the pan on it, but stole the heads for a beater truck engine.

[ 07-25-2005, 11:29 AM: Message edited by: john8662 ]

[arveetek]

I don't see any reason not to drop the compression a little, especially since you're going to install the turbo. If you were sticking n/a, then I would probably stay with stock compression. But the turbo adds heat and pressure to an already extremely high CR, so I think lowering the compression is a good way to help the engine last longer. I did mine mainly for longevity, not for a power increase.

I would also recommend shaving the heads and block. I know, I know, it's a lot more work and money, but I think it's worth it to get a good seal on the head gaskets. Of course, you have to shave the block, and then find out how much was shaved off, and then order the pistons to match, and then bore the block to match the pistons...it's a real pain in the neck, I know, but it makes a much better product that will last a long time without fear of blowing head gaskets.

Casey

[john8662]

I'm skeptical about dropping the 6.2's compression for what I'm going to be using the truck for. Mainly for several reasons.

First, the piston is shaved .010, so in my mind that makes the piston thinner, but it's having to withstand less compression.

Second, cold starting, I'm doing an 18:1 build on my 6.5, and when it's cold, I want something that'll fire right up no matter what. Having the C/R at stock on the 6.2 will also give me some ground to compare the higher compression verses the lower compression of the new 6.5.

Decking the block? I totally understand the reasons behind this, but...

How about an engine that didn't have any problems with head gasket failures, and the deck isn't eroded or messed up in any way? I figure, if it went as far as it did with the surface it had, then it's likely to go just as far again with better quality head gaskets and bolts than what was probably used in 86. But, I do realize that I need to have the deck height checked, as these engines are prone to vary, which will be a problem. Hmm...

One thing about the turbo that I'm going to use though, it's a mild turbo, that from others I've talked to say it makes 6-7psi and thats about it, but it SPOOLS fast. I've got a friend who has a 6.2 in a suburban, with over 300k miles on it, had the ATS added when the engine was new, never a problem with head gaskets, and the thing still goes 3000 miles w/o using any oil. He wants more power out of it, but it works well for what it's being used for. The only problem to date that I know of engine wise was 1 lifter, that was repaired with the engine installed.

I appreciate your input on the lower C/R though!

[dieseldummy]

Sounds like next time I'm down in Texas I better pick-up some cheap extra parts for my fix it and sell it project... My .02 on compression it leave it stock, my 18:1 was a hard starting pain in the rear when it was warm, I can only imagine cold.

[john8662]

Casey,

I've got a quick engine building question for ya. I took a look see at all the bearings on the engine. All the main bearings are the OS bearings at the .013mm stamped on the back, except journal number 3 which is more OS at .026mm. I went back and looked at all the rods, because I still have them together because of stuff like this. All of them were standard except for the #7,8 rod bearings, and only on the rod cap side, the rod side bearing was standard. These were the .026mm bearings.

I'm starting to think I need to turn this crank, thats what Benny Suggested, but I'm leary of a suggested .010, .010 crank.

I was wanting to polish the crank then balance it, but if I polish it, then it'll all be out of spec (just a speculation). I don't think I have another crank thats great.

Just curious if you ran into this?

I need a better mic to to the journals, I just have the C clamp style (you know what I'm talking about).

[ 07-26-2005, 06:34 PM: Message edited by: john8662 ]

[john8662]

Just an update...

The machine shop called and said that my heads are rebuildable, so thats good news. So I gave them the green light to go ahead and rebuild them and surface them. The guides were gone, so thats the cause of the buildup on the intake valves, oil. They also pressure checked the heads, the one head with the cracks beetween the valves doesn't leak, so were're gonna go with em. Also, it needs a few precups. yada yada yada.

I've also placed an order for a set of .020 coated pistons at the stock C/R.

And.. most importantly, I now have the $ for the parts, thanks to my local bank note on an 80's model truck engine... :cool:

John

[EWC]

John , I'm in the same boat as you . Mind if I ask what a set of pistons cost ?

[arveetek]

John, as far as your bearings question:

I know that GM used a select-fit bearing process, by which they installed different sized bearings on one engine in order to get the best fit and clearance. I didn't know this when I originally overhauled my engine in 1996. I just installed a new set of standard sized bearings, and all the oil clearances were fine. So, when I rebuilt the engine this time, all the bearings were the same size. I simply bought a new set of standard bearings, checked the oil clearances with plastigage, and all was fine.

I know that the standard bearings will be okay, because it ran 120K miles on standard bearings. There wasn't much wear after 120K miles either.

If I were in your shoes, I'd probably buy a set of standard bearings, install the crank, the then check the oil clearances with plastigage. You might not have to polish the crank or anything.

Casey

[john8662]

Progress!

Well.. not that much progress.

I have the new pistons from TDD for the engine, but it's taken this long to get a good set, believe me, it's a long story, but hopefully with a happy ending.

Anyways, I've got the block down at the machine shop, here is whats been done so far:

-Block deck checked, given clean bill of health, needs no decking.
-Cylinder bore diameter re-verified (turns out I can operate a mic with accuracy!)
-Crank being checked, probably use .001" OS bearings across the mains,
-Rods having new wrist pin bushings installed
-Rods size will be checked on the big end.
-After crank usability is verified, will be balancing the rotating assembly.
-Very important: Hidden oil gallery plug removed prior to final cleaning.

Now, the question at hand, I think I have the answer, but we'll see.

Machine shop called and said they wanted to know where I wanted to set the cylinder to bore clearance on this engine, this is from after mic'ing the pistons.

Here is what Jamie told me for the pistons used:

1-6 .004"
7-8 .0045"

Because according to the GM book on the 6.2 you add .0005" (1/2 thousandth) for cylinder to bore clearance on top of what the clearance is. Of course the book only lists Zolhner and Bohn pistons.

The pistons I'm using are Clevite boxed pistons, but marked Mahle on the inside of the piston skirt. So, I downloaded Clevite's Engine Parts catalog and it said to use:

http://members.cox.net/acmdsl/clevitepistonspec.jpg

So.. Clevite is using a full .001" extra clearance on cylinders 7&8 instead of what the GM book called for being .0005" clearance.

I think I'm going to go with the tighter of the two and go with the TDD's recommendation of .004" .0045" clearance.

[arveetek]

John,

I set my clearances at .0035" for 1 through 6, and .0040" for 7 and 8. I just read Ronniejoe's new article, and he set his at .0040" for 1 through 5, and .0045" for 6, 7, and 8. Mine are tighter than that, and I went by the book that I had. Around 4000 miles on the engine now, some of those are hard pulling miles, and no problems. I wouldn't go any larger than .0045".

The DD pistons I used also came in Clevite boxes, with "Mahle" stamped into the skirts.

Casey

[mhagie]

Why the extra clearance omn 7&8? Mine does not run that hot at the rear of head, in fact it runs 10* cooler at rear of head than at factory port or t/stat housing.
confusing to me.
Merle

[arveetek]

Apparently 7 and 8 do run hotter....from what I've gathered, most engines that fail due to heat have galled cylinders in 7 and 8. Ronniejoe says that when he tore his engine down, he found galling on 6, 7, and 8. That's why he allowed a little extra space.

I've heard of an awful lot of 6.5L engines that failed due to problems in 7 and 8 that were heat related.

I think in order to verify your readings, you need to use the same kind of temperature guage at all places. Perhaps the digital guage is more exact than the mechanical guages. The best thing you could do, would be to swap locations on the sending units for a while, if possible. This way you could verify the readings. If the digital guage shows 10* cooler when reading the front, and the mechanical guage shows warmer reading the rear, then you know there's a discrepancy in the guages.

Casey

[dieseldummy]

I often wonder if some of the galling in the rear cylinders isn't from to much clearance letting the piston rock around in the hole. 6&8 on my first overhaul were worn and galled much worse than the others, 8 had symtoms of excessive piston "slop". There were physical waves in the cylinder wall caused by to much clearance with a short skirted piston...

[john8662]

Well the engine is bored to .020

This project is going to be a long winded one, I hate to say it, but I know that this truck probably won't run this year, it will be early next year :eek:

But.. Hopefully I get a chance.

This is mainly due to having to buy a part at a time, and getting things coordinated, plus working on the 6.5 engine project at the same time...

Thanks for the points on cylinder bore clearance!

DD, I do agree that there is a possibility that the little more bore clearance in the back two cylinders probably does contribute to more uneven wear in the form of piston slap.

I'm interested in Caseys engine being built to tighter tolerances. But for the record, Peninsular is building their engines to about that clearance, so it's probably not a problem.

[john8662]

My baby is back home, now some assembly required...

The machine shop called me and said that they had everything finished on the 6.2 and that I could come pick it and the parts up.

Cool!

So, what I picked up:

6.2L block, .020 bore, new cam bearings installed.
Balanced crankshaft, and new flexplate.
Rods, resized on the big end, and with new pin bushings
Heads, surfaced, new guides, seals.

on the way...

New Torque convertor for the tranny
New gear drive, we'll dig deeper there
New cam.

Still on the list,

need an exhaust system for the new turbo.
Amsoil air filter (must have).

The project continues, I need a break from the 6.5L project (yeah , you know) so I'll play 6.2 mechanic for awhile (I promise I won't feed it any nuts).

smile.gif

[dieseldummy]

Cool John! I hope this one treats you better than the 6.5. I bet this one will be a runner!

Justin

[john8662]

Well.. Another stand still.

I was doing the "right" thing and checking piston end gap and came to the conclusion that it's out of spec.

My book shows a max gap for the 1st compression ring gap at .021" and I'm at .024" the 2nd compression ring gap is supposed to be larger, but my end gap that I measured was at .020" and that gap is supposedly too small (I can fix these if necessary though).

I took the time to check the piston diameter and compare it to the cylinder bore diameter and came to the conclusion that everything looks good there, I'm at .004" bore clearance, according to where I measured. Don't see a problem here..

So, I'm looking for another ring set to try at this point.

And, well, no one in town has .020 rings for a 6.2, so it's up to ordering them.

[john8662]

Well, This ring problem seems to be the biggest concern stopping the build currently.

A few observations, but first the specifications for what the ring gap should be:

Upper Compression Ring Range .012" - .022"
Second Compression Ring Range .030" - .040"
Oil Control Ring Range .010" - .020"

The first set of rings were Hastings rings, and upon checking the two compression rings I came to these specs:

.024" Clearance Upper
.021" Clearance Lower

So, the Upper ring is has too much gap, and the second ring has too little.

I ordered another set of rings, this time to match the Mahle pistons.

They came in at:

.023" Clearance for the Upper compression ring
.041" Clearance for the Lower compression ring

So, what gives? They're out of spec, but not by much. This is just one of those things that we rarely check, but I view as very important.

I've checked the bore in comparison to the piston size, and I come in at .004" bore clearance. Right where I want to be, but the rings are too loose. If I were to have gone with the .0035 bore clearance, I would probably be just in the ring gap range...

So, whats a person to do? Are the pistons slightly larger than a .020 OS, causing the rings to be off because the block was bore according to the pistons?

I don't know, I'm debating going with Total Seal Gapless rings, and I think that others may have run into this with 6.2 or 6.5 builds and gone this route because it was the only way to recover. At least with the gapless rings I can size them (according to the specs).

Input?

[BobND]

Here's some thoughs on ring end gaps by an "expert":

http://www.dol.net/~dave.reed/tips.htm

[john8662]

Something not checked, ring clearance in piston.. Yes, but these are new pistons.

The equation given on the site for ring gap clearance is .003" per inch of bore. So, 4" bore x .004" = .016" and this is for hard usage engines according to the link.

[ 11-27-2005, 06:46 PM: Message edited by: john8662 ]

[BobND]

Did you notice his claim that 95% of blowby is between the ring land and the ring, leaving 5% leakage at the end gap?

I wonder how accurate this is?

[john8662]

I did read that, but kind of blurred past it because it wasn't what I was reading for. But, I don't know how accurate that percentage is on blow-by past the ring into the piston groove. But, I can sure see that this would be a problem in rebuilding an engine where boring the engine wasn't required and the pistons were re-used.

I will check the ring clearance in the ring groove on the new pistons, since I'm there.

[EWC]

John , how are you positioning the rings for measurement of the end gaps ?

[john8662]

EWC,

I'm taking the ring and compressing it to go into the bore, then I take a bare piston and guide the ring with the top of the piston (to keep it square in the hole) until I get to the mid point. I'm leaving the gap at the bottom of the bore, mainly for ease of access, then I measure the gap with feeler gauges. I tried to rotate the position in the bore where I was measureing, but it didn't make any difference on the gap.

Well, I called my machine shop that did the work. Here is the deal. I was informed that the gaps that I've got are so very close enough that I should use what I've got. The man I talked to who runs the shop said that the .020 pistons used aren't necessarily .020, they're usually a little bigger. So, since I had the block bored to the size of the piston measurement (plus clearance) that I was going to run into this.

I could go gapless and size them from there, but, the money tree has been dead for a long time, and I'm going to use what I've got now. I need a new job, I've started looking but ain't turning up much, Gov jobs suck on pay!

[john8662]

FINALLY!!

I'm sure working on this slowly, but I finally have something to show for my work.

The engine is getting close to assembled. I assembled the shortblock over the weekend, checking everything clearance wise. The mains came out at .003" clearance (using STD mains), the rods are .002" clearance (using .001" or .026MM bearings). The heads were bolted on Monday night, lifters, etc.

All I have left are mounting the "tins" and installing the timing set, as I'm going to be waiting for a new cam gear for the timing gears, the one supplied is chipped up. I'm a bit worried about taking the 'ol file and cleaning it up, because it's a timing component. This should and will be a warranty item.

Just posting, because I haven't given up! Hope to have it running by the end of January, I miss my truck!!!

Still have to sort out the turbo stuff, my turbo needs to be taken apart, build the exhaust system (still a question), and order a replacement 6-bolt (no more INFERIOR 3-bolt) Torque Convertor.