When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So I knew I had bad compression in cylinders 5 and 7, I also knew there was a little surface rust on the valves on those cylinders. I pulled the head off to assess the damage and this is what I found. I'm very experienced in working on cars, but this is my first deep dive inside of an engine.
This is a stock junkyard 5.3 L59 that is going to get put in my K5 Blazer. I got it for pocket change compared to most. Am I looking at something I could fix with a ball hone and a re-tube or is this full on send it to a machine shop? Or am I just better off just buying another one?
If you’re on a tight budget, a ball hone and rings would get you by. The rust doesn’t look deep except in a few small spots. If you want it done right, and to last, have it honed .005” at a shop and get new pistons. Really depends on long term goals here. I’d go ahead and tear it all the way apart and have a looksey first at everything.
If you’re on a tight budget, a ball hone and rings would get you by. The rust doesn’t look deep except in a few small spots. If you want it done right, and to last, have it honed .005” at a shop and get new pistons. Really depends on long term goals here. I’d go ahead and tear it all the way apart and have a looksey first at everything.
Basically I have the budget for the engine swap itself right now. Machine work on the block is stretching it. If I could make this engine run and drive for about 3 years, I'd be happy to pull it and do a full rebuild after that.
I would clean the surface rust off with a fine scotch bright and then see what you have for pits. I've seen worse run just fine and regain some compression after it's had a chance to wear back in if the pit's aren't deep. That looks more like surface rust from condensation rather than water leaking in. You'll have to decide if it's worth taking the time and money to drop it in and run it to see how it performs. You have the cost of gaskets/bolts/oil and your time.
I would clean the surface rust off with a fine scotch bright and then see what you have for pits. I've seen worse run just fine and regain some compression after it's had a chance to wear back in if the pit's aren't deep. That looks more like surface rust from condensation rather than water leaking in. You'll have to decide if it's worth taking the time and money to drop it in and run it to see how it performs. You have the cost of gaskets/bolts/oil and your time.
I'm pretty positive it's just from condensation judging by what I found on the rockers. I might try some fine steel wool and wd40 and see how it looks. I guess I can't make it much worse than it is.
I think you'll be fine just cleaning off the rust and running it.
I'm guessing this isn't a max-effort build, and as others have said, I've seen worse on engines that were running just fine when they came in for other repairs.
I think you'll be fine just cleaning off the rust and running it.
I'm guessing this isn't a max-effort build, and as others have said, I've seen worse on engines that were running just fine when they came in for other repairs.
It's a long way from max effort. I could be down 40 or 50hp and I probably won't care. I just don't have a feel for how much is too much to be usable.
After you clean the rust off it should feel fairly smooth everywhere unless it's pitted, A few pits aren't a deal killer. If you have a decent amount that feels like orange peel or worse when you run your fingers across it you may have some blow-by when you run it. From the pictures it doesn't look that bad.
So Ill be the first to bite. Would cylinders that are low on compression be that way because of something other than a head gasket leak? I was going to reply with the thought of just doing head gaskets and throw it back together lol.
For the sake of learning something, what makes this engine need rings just from photos? The fact it had known low compression?
Ok, so I shouldve said to me it looked like a head gasket leak. Normally that causes the rust in the cylinders. And to me it doesnt look that bad, but I guess bad enough its wise to just take it apart and hone the cylinder and clean everything up and do new rings?
I opened up a 5.3 I bought off ebay and rebuilt it (head gaskets, lifters, springs, oil pump, ARP bolts), I didnt notice anything like this so I just went about my merry way and put it back together.
like I said I would leave the rings, the factory rings are excellent and are good even with 300,000 miles on them.... (unless it was ran with the cylinder walls jacked up)
The engine above looks like that from a valve being open on that cylinder and sitting in a humid/wet environment for an extended period of time, not from a head gasket leak
like I said I would leave the rings, the factory rings are excellent and are good even with 300,000 miles on them.... (unless it was ran with the cylinder walls jacked up)
The engine above looks like that from a valve being open on that cylinder and sitting in a humid/wet environment for an extended period of time, not from a head gasket leak
Bingo. This was sitting in a back yard in South Carolina for about 2 years. Tahoe still had a hood, but no fenders.
So Ill be the first to bite. Would cylinders that are low on compression be that way because of something other than a head gasket leak? I was going to reply with the thought of just doing head gaskets and throw it back together lol.
For the sake of learning something, what makes this engine need rings just from photos? The fact it had known low compression?
In my case (the engine above) the oil was "clean", it had no water in it, the entire passenger side bank has good compression and so did cylinders 1 and 3. That pretty much confirms it's not a head gasket. I'm pretty sure my bad compression on 5 and 7 are a combination of what you see above in cylinder 5, and surface rust on the valves for 5 and 7, which is what I pulled the heads apart to fix in the first place.
How screwed am I? 
