Anyone with heads off the block?
TReK
Joined: Jul 2017
Posts: 3,387
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Exhaust ports were not coated with any oil but sooty. Spark plugs white ash in the electrode but heavy black elsewhere.
Cross hatch vey fine. So smooth can’t even feel it and looks like mirror when viewing. I’m generally knowledable on mechanically related stuff and not my first rebuild but I don’t have enough experience to understand what to look for and what I am seeing. Not often you get a chance to look inside an engine with 800 miles.
I agree the vertical scuffs on the cylinder wall are unusual so will inquire more on that. I know my pistons are .002 too small due to rehoning from the first rebuild for same oil burn problem. I’ve done this before and the shop has too so I don’t think it’s the cause.
Cold compression with intake off was 140-150. No leak down test
Cross hatch vey fine. So smooth can’t even feel it and looks like mirror when viewing. I’m generally knowledable on mechanically related stuff and not my first rebuild but I don’t have enough experience to understand what to look for and what I am seeing. Not often you get a chance to look inside an engine with 800 miles.
I agree the vertical scuffs on the cylinder wall are unusual so will inquire more on that. I know my pistons are .002 too small due to rehoning from the first rebuild for same oil burn problem. I’ve done this before and the shop has too so I don’t think it’s the cause.
Cold compression with intake off was 140-150. No leak down test
.002" isn't much, but that's .002" below spec, more if it's been honed again since.
I would measure the piston diameters, and cylinder bores. Then, check the rave for the max clearance allowed, regardless of what the bore is (forget about the rings for now).
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Rock Crawling
Joined: Aug 2017
Posts: 263
Likes: 32
From: South Dakota
If the pistons were .002" small, and the last time it was honed. Do you mean it's been honed again since that?
.002" isn't much, but that's .002" below spec, more if it's been honed again since.
I would measure the piston diameters, and cylinder bores. Then, check the rave for the max clearance allowed, regardless of what the bore is (forget about the rings for now).
.002" isn't much, but that's .002" below spec, more if it's been honed again since.
I would measure the piston diameters, and cylinder bores. Then, check the rave for the max clearance allowed, regardless of what the bore is (forget about the rings for now).
TReK
Joined: Jul 2017
Posts: 3,387
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Now after the rebuild I just did. I had it honed to seat the new rings. I have no spec on these pistons. Assume they are custom as I cannot find any suppliers that sell 3.780 pistons or rings. I’m not willing to invest $1500+ at this point for a new set of custom pistons when I’m not sure if the problem is even related. Or at least not today lol
So measure piston and bore diameters, and compare the clearance to stock spec clearance.
That will answer the question.
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Rock Crawling
Joined: Aug 2017
Posts: 263
Likes: 32
From: South Dakota
I don’t recall offhand but had that discussion with the shop back when we honed it. I know it was beyond the .001 - .002 RAVE spec. They recommended I run it that way rather than invest in replacement pistons. I’ll admit it’s suspect but the shop swears it’s not the problem. And they have nothing to hide or cover up so I trust what they are saying. I’ll have to measure again and they want to take a look at it again too but I’ve been out of town so haven’t dropped it off.
TReK
Joined: Jul 2017
Posts: 3,387
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If the rave calls for a .001-.002 tolerance, that is a very small and tight tolerance.
It is made that way for a reason.
If it is out of spec, and the engine was an oil burner before, then that sounds like it is the problem.
I would buy pistons, rings, and hone the block.
Cuss and spend the money.
Or, quit and sell it for hundreds.
It is made that way for a reason.
If it is out of spec, and the engine was an oil burner before, then that sounds like it is the problem.
I would buy pistons, rings, and hone the block.
Cuss and spend the money.
Or, quit and sell it for hundreds.
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Rock Crawling
Joined: Aug 2017
Posts: 263
Likes: 32
From: South Dakota
Given all the measurements, Hastings requested to see the rings and a piston so they can determine the problem and the possibility that the rings are defective.
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Rock Crawling
Joined: Aug 2017
Posts: 263
Likes: 32
From: South Dakota
*Update* I got extreme and bought a used Rover P38 Bosch engine from a guy that cracked the tranny and transfer case from a bad u-joint. Swapped out the short block but reused my SAI heads. Excited to have my major oil consumption problem fixed, I started it up and drove 100 miles. Used almost a quart of oil still! At least it Narrowed the problem to the heads. Shop used Teflon small block Chevy valve stem seals saying they are the exact same. I questioned this 3 different times with them and they convinced me each time it’s not the problem. I finally followed my hunch and changed to Rover seals. Problem fixed! What an ordeal. Haven’t received the rings analysis from Hastings but I now believe the rings are good. Excited to have this nightmare over but now I have a used engine in my truck and my top hat rebuilt engine sitting in pieces on a pallet...ugh. I tore down to the intake no less than 5 times and the engine out twice. Positive is I can get the upper intake off in less than 30 min and the intake off within 2 hrs. Haven’t talked to the shop yet as I’m not sure what to ask in return for their obvious error in parts used. I even gave them the proper seals to use but they claimed the Teflon are superior.
