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Thread: Want to get some opinions on this cylinder wall..

  1. #1

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    Want to get some opinions on this cylinder wall..

    Hi everyone. I was getting ready to redo the head on this truck, and saw these marks in the very back cylinder, so I wanted to post here and maybe get some advice on what I should do about it. The oil in the coolant is from me spilling some into it. It was green.

    The truck is an 87 mighty max with the G63B, and manual transmission. I was wondering if I should just go ahead and put a fresh head back on and hope for the best?... or see if I can remove the pistons by removing the oil pan, honing the cylinders, and replacing the pistons with new ones. I'm not sure if that's even possible on this truck without pulling the engine, but it looks like it could be done. I'm also not even sure if that's piston material imbedded into the cylinder wall or not, so I wanted to ask.. I can't feel it with my fingernail if that means anything.

    I guess I should also mention that there was coolant sitting in the bottom of this cylinder on top of the piston for a while. This has been sort of a slow project for me. I've had the truck for a few months now and I have been keeping oil in the cylinders just to prevent rust, and I recently within the past month or so moved to a new house and towed the truck on a trailer with plastic wrap over the block, and I think some of the antifreeze from the rear coolant passages spilled over into the cylinder and was just resting in there, until today.. guess I should have drained the coolant.. oh well too late now. I never saw any coolant in that cylinder before moving it so that's why I think it was from moving the truck here.

    The engine was overheated by the previous owner and the head gasket blew, and when I took it apart, the head was cracked in between one set of valves, not a super bad crack, but cracked nonetheless. So I went and pulled a head at the junkyard and had it cleaned, decked, and got them to do a valve job on it. I did all this assuming the block was ok, which was stupid on my end for not checking all the cylinder walls for wear.



    I appreciate any advice I can get, thanks.

  2. #2

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    I was trying to find an edit post button but couldn't find one. I just want to mention I don't remember seeing these marks before the move, but it's entirely possible I just never noticed them.

  3. #3

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    Hm, when checking ridiculously expensive glass for cracks that are invisible to the eye, the trick is to run your fingernail over the suspect area backward, not forward, to feel for cracks. So maybe run your fingernail both ways/all ways to make sure you really can't feel damage on that cylinder wall.

    Personally if I couldn't feel damage, or see any damage looking at it from all angles possible with a flashlight to reflect light from every possible angle, I'd put the head back on and hope for the best. But your answer would depend on a few things, how many miles are currently on the block? How many miles do you want it to keep going without having to redo anything? 10k? 60k? Ever? Do you have any idea of work done previously? Someone could have replaced cylinders and left the walls as-is in the past maybe?

    Also just thought of an alternative idea (so discount if you wish) but if you turn the engine to get that cylinder up to where suspect damage is, and put fluid in it, does it leak down over a few hours/days? Fluid will go in cracks we can't see & you're going to have to flush everything anyway after the job is done.

    Surely someone else will comment, but wanted to give you some ideas in the meantime Good luck!

  4. #4


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    If you are going to re-build, you will need to pull the engine, no way you can do what you want with it in the truck. besides it will be easier and quicker

    to get the work done.

  5. #5

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    Thanks for the replies. I did bring that piston up to that spot and pour oil into it, and it sat in there for 2 days without leaking down so I brought the piston down and put my fingernail to it again and felt it drag a little on the middle of that corroded looking spot. My fingernail didn't catch it, but it did drag over it if that makes sense. The engine has had head work before. And it has 234k miles on it.... Doesn't sound good I know.

    I'd love to just rebuild it. And I'd tackle it myself if I could do it for less than 200 bucks. I have the tools to rebuild, but I haven't looked up the cost of parts, and possible block machining for that. But if I can just pull the pistons and hone the cylinders, then put in new pistons and rings I'd be happy.

    I hear you can reuse rod bearings as long as they're put back in the same place, but with this many miles.. Idk.

  6. #6

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    Hm, I wonder now how many times there's been cylinder wall 'damage' on the 2 cylinders we normally don't see because the pistons are always 'up' on 2 of them. I for one didn't even think to rotate the engine to look at the #2 and #3 walls, HA! And i had it apart for about a month... never dawned on me. Now I'm wondering if that's why I seem to be burning a little oil... hmmm. No way in hell I'm pulling the head again to look either. Mine had overheating issues also. No big deal to keep an eye on the oil level at least with no long road trips.

    Coolant is bound to splash around a bit. But you'd probably flip out if that block has a crack you didn't notice yet, too. I'd be inspecting every last bit of it, then clean it up real good, fill all the coolant passages with coolant and see if you lose any - or if any shows up where it shouldn't. Keep in mind though sometimes a crack is so small though fluid won't show up elsewhere if it's not under pressure... Is there a dye that can be used to help with seeing that? I'm not sure. if any disappears, keep adding it until you can see where it's going.

    Ok so for under $200, man you'd have to get real lucky to not find anything else that needs attention at that many miles, it's a slippery slope since once we get in that deep, it's silly not to make it all 'perfect'.

    On one hand, did you hear it run before ? No rod knock or anything to indicate lower end issues? No metal bits whatsoever in the oil when you drained it? Have you pulled the oil pan to look? Depending on all that I'd figure when you're willing to part with more than $200 then deal with a complete rebuild if needed.

    IMHO that little bit of damage on that wall isn't going to make any thing ELSE go bad that isn't already. Since you already had the head off, the 2nd time will be so much faster for you - and the rumor is that it's much easier to work on anything w/the engine out.

  7. #7

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    At first i was winced when i saw the pic of your cylinder wall. However after looking at it a couple times, doesn't look like actual wall damage. Looks more like something just built up on it. It looks too white to me for it to be parts of the piston embedded in the wall. So i took a look at mine and this is what it looks like now.



    Looks similar. I can feel it with my nail when i run it over it. I'm 100% positive that wasn't there when i pulled the head off. Head has been off for approximately 3 weeks. Its only on one of my cylinders, the one that had the head crack between valves and was dumping coolant. So its probably just some form of build up from the left over anti freeze residue and being exposed. I'm not gonna worry about it.

    Mine has 221k on it. Before i pulled the head i did a leak down test and the 3 cylinders that didn't have a crack in the head help compression great. Your cylinder walls look to be in much better shape than mine are. If i was in your spot, i would just throw a head on it and be on my way.

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