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I fully understand.....
Clean it up...Stuff a set of gaskets in that sucker and run it like ya stole it....
Personally under the circumstances I would not worry too much about that crack.
If the head gasket had not gone away....we would not be having this conversation...:rolleyes:
Last night I was able to get the 1997 506 engine disassembled to see what was up inside that motor. It was running when I pulled it out of the C3500 truck it was in several years ago, but had almost zero compression on one cylinder and was missing.
Turns out the engine must have ingested a glow plug; the piston top was beat to heck and the exhaust valve was damaged with a chunk missing out of it:
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I put a light in the exhaust port.... there shouldn't be light shining out behind the valve!
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The rest of the engine looked great! No cracks that I can see. The cylinders still show the cross-hatch marks:
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The only issue I have found so far is that the cylinder with the damaged piston has some very light scoring:
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My plan is to remove that piston and hone that cylinder to see if it will clean up. If so, I will then use this short block, swap a piston in from my 95, use my 95 heads, install new bearings, rings, and headgaskets, swap over my nearly new water pump and timing chain from the 95, and then I should be good to go.
Casey
Is it a Squirt block ???
Yes it is!Quote:
Originally Posted by Robyn
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I went ahead and pulled all the pistons and removed the crankshaft so that I could really inspect this block, and there are no cracks anywhere. (I read another post where one guy didn't find any cracks until after taking the crank out, so I wanted to be real sure.) The only issue is cylinder one has some slight scoring.
This is after after I honed the cylinder for a few minutes:
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I've almost got it honed enough to where I can't feel the line anymore. I'm going to keep working on it, and as long as I can't feel the line, it should be good to use, correct?
Casey
Myself i probably would stop where you are.
As you hone you are making the bore bigger and losing some of the compression ability of the rings.
The small imperfection that is left will probably fill with carbon and be a moot imperfection.
I went ahead and honed the cylinder a bit more, and she cleaned up real nice!
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I then checked the cylinder diameter by measuring the piston ring end gap, and she was still within specs:
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I then moved my attention back to the heads. My intentions were to use my original 1995 heads, but upon cleaning them up, discovered they were cracked between all the valves in all 4 spots on both heads:
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So then I decided to clean up the 1997 heads, and was pleasantly surprised to find no cracks at all. These heads even had the diamond pre-cups:
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The only issue with the one head is where cylinder 1 ingested a glow plug and banged up the head and damaged the exhaust valve:
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Luckily the valves in the 1995 heads are in great shape, so I can use those valves. I will lap all the valves and put in new seals.
This area is pretty banged up, but since the firing ring area where it seals to the block is fine, this shouldn't affect anything, correct?
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So things are looking up. This 506 block out of a 1997 C3500 utility truck with low miles looks really good. New rings, bearings, head gaskets, head bolts, seals, and an oil pump and I should be good to go. I'm about ready to start ordering parts (finally!!).
Casey
The 95 heads don't look that bad. Cracks between the valves are common and aren't a problem if they don't leak. The 97 head in the pic needs a date with the mill. The impact damage probably won't be an issue, but it needs to be cleaned up and true.
I would look at the valve seats in the 95 heads....If the seats are not cracked....run them...
The 97 block looks great....
As I mentioned before...be sure to run the 97 oil pump (High volume)
Check the deck on that banged up head.....If it is flat....I would use it as is....A good "True" straight edge and a skinny feeler gauge.....see if it is warped....
Cutting the head is quite doable....But on the 6.2/6.5 the valve recess is important....Cutting the heads can lead to starting issues.
I am not sure why this is...but IIRC after reading a service bulletin some years back....I read about this anomaly...
I have run heads that make yours look pristine........
Also I would say to replace the one valve with a fresh one and lap it in....The others are all happy.... If it ain't broke ya know... Just clean things up and remove any carbon buildup on the valve heads.....Then check the seat contact with prussian blue... (https://www.google.com/aclk?sa=L&ai=...gQIARBB&adurl=
If the contact is good....run it. Really no sense in making yourself more work.....
With the seat clean and a thin smear of blue on the valve seat....Slide the valve in an lightly Tap it on the seat.....Look at the contact pattern on the seat and act accordingly.
I am nervous about that one seat after getting thrashed as it did.
Looks good
Should prove to be a pretty good engine .....
(ADDITION)
I found this excerpt from an article that spoke of the valve recess
Pushrods for this engine are specific in their orientation in the engine. They have a very specific difference in their hardness from end-to-end. The side with a paint stripe or copper coloring must go to the rocker arm side or the top of the engine. Failure to install the push rods correctly will result in premature engine failure without question. Valve recession for both the intake and exhaust valves is .034″ – .048″ – being outside of these specs will result in hard starting, white smoking and/or runnability issues.
Quote:
Originally Posted by DmaxMaverick
Yes, I agree. I have the heads loaded up and will get them to the shop this week.
Quote:
Originally Posted by Robyn
Thanks for the info. I decided to take the 97 heads to the shop to have them resurfaced and have them go through the valves.
The block deck is nice and flat; the heads... not so much. I think they're within spec, as my GM service manual says .006 is acceptable, and I measured .005 warpage. But there's some pitting I don't care for, and it makes me nervous to try and run them as is.
I also came across this in my GM service manual:
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I know that resurfacing can be done (I've done it with success on my old 6.2L), but would I be wise to get the .010 thicker gasket from Felpro to make up for the milling on the heads?
Casey
"Valve recession for both the intake and exhaust valves is .034″ – .048″ – being outside of these specs will result in hard starting, white smoking and/or runnability issues." Reads like something from GM and I have no doubt it's accurate and from real world testing. I just don't see how valve recession outside those limits would cause those problems. If they were recessed a little too deep, it would lower compression at TDC and cause hard starting? Surely it couldn't lower compression to that degree with a small amount of recession outside those limits? And white smoke is unburnt fuel. A little extra valve recession causing incomplete combustion?
Been there...done that...It is real.
I can't tell you why....But GM likely would not spend the time and effort to print it if it was of no value.
Taking off a bare minimum should not hurt.... BARE MINIMUM .002" OR SO and be sure the valve recess is within spec.
Using the +0.010" gasket won't hurt anything, and would certainly account for any concern about the height. If the engine or heads have been previously messed with, be sure that's not where you are already, or worse (Robyn can comment on that). Can you read the label on the old gasket? are there any scribe/stamp marks on the block deck or head? Definitely measure piston crown and head height to confirm.
OHHHHH YEAH BUDDY
Get the crank in (Only need a couple bearings) one piston/rod assembly "No rings needed"
Run the pistons to TDC and check the piston to deck location.
Should be flush with deck to .002" or so above
I had a block that had one side decked at .010....I bought the "Crack free block" from a rebuild supplier.... ASSUMED THE BLOCK WAS AS MANUFACTURED (BAD PLAN)
We decked the block .015" to clean it up......At assembly one side had the pistons hanging out of the block .025" OH !@#$%^
That ended poorly.
Bought a special MLS gasket to fix the issue.
Lasted a year and started leaking pressure to cooling system.
Ended up building a fresh AMG block (Another long story)
Just verify where the pistons are in relation to deck....and be happy......Too many engines get massaged and nothing is stamped on the upper deck flanges.
Never assume anything on these things....it can turn ugly and get $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$
I remember that whole ordeal!Quote:
Originally Posted by Robyn
I assume this engine has not been touched; I pulled the engine myself from a low mileage 1997 C3500 city utility truck. But, we all know what ASSUME means..... :D
Thanks again for all the advice!
Casey
I remember when I had the engine shop do the machine work on our 6.5TD Power Project engine, that the valve guy said he returned the geometry of the valve train to stock after decking the heads and block by trimming the valve stems. I don't think the +.010 Fel-Pro head gaskets were available then. I agree with DMaxMaverick, the head decks look like they need to be machined.
I had a 6.2L head back in the early 1990s that had one combustion chamber where coolant/water had eroded the cast iron, making it look like the deck area on the head you have here. We/they just did the machine work on it, and we re-used it. Not a problem...
Jim
The gaskets off the 1995 engine are FelPro 14098623. The gaskets off the 1997 engine are FelPro 12554979. I haven't discovered any scribe or stamp marks yet.Quote:
Originally Posted by DmaxMaverick
Casey
Those are GM part numbers. Are you sure they're Fel Pro? Fel Pro item numbers are 5 or 6 digits, usually with a letter.
Yes, they are definitely stamped with the FelPro name:Quote:
Originally Posted by DmaxMaverick
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Casey
I'm trying not to let the "might as wells" get out of control, but I have noticed lately that the torque converter was slipping a bit when locked up, especially when towing. I had planned on tossing in a new torque converter while the engine was out, but after a 30 minute phone call with my transmission guy this happenend......
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I mean, 376K miles on a 4L80E is pretty darn good. It will be way easier to rebuild it now, and probably cheaper. If I wait until it fails, it could grenade and cost a lot more to rebuild.
*sigh*
Oh well... when this is all said and done, I should have a reliable rig to get me down the road another 300K!
The heads are currently at the machine shop; hope to have them back next week.
I just ordered $1500 in parts today - rings, bearings, gaskets, motor mounts, injectors, starter, etc. Pretty much everything will be new in the drivetrain except for the power steering, alternator, and A/C compressor (compressor is only a few years old, as is the alternator; I've never touched the power steering pump....hmmmm...).
I figure for under 5 grand I will have a new engine, new transmission, and rebuilt transfer case. I couldn't buy another decent 6.5L rig for that money, and it would barely be a down payment on a new truck.....
Casey
If the power steering pump has that many miles on it, I'd replace the front shaft seal. Mine went bad around 200 thousand. You'll need a special puller to get the pulley off. Autozone has them.