Corrosion on cylinder wall
 

I recently bought a 65000k vvt engine from the junkyard. I removed the head to install a 99 head gasket and freshen up the head with new valve seals and I found a little bit of corrosion on cylinder number 3. I'm trying not to spend too much money on it, would you guys hone it, install new rings, bearings and oil pump or just run it like this?
The corrosion is about 1/4" in diameter and I can't feel it with my finger
https://www.miataturbo.net/attachmen...ine=1449097225

I don't see any carbon at the top of the cylinders, so I assumed you've already wiped it down with brake cleaner/an oily rag?


I would want to try to hone it first, if it doesn't clean up with light rubbing. I also see some very small vertical lines near that area. Your finger tip (not your nail), can't feel it?



Worst case a VERY light bore would take it out.

Yes I wiped it down. No, I can't feel it with my finger either. I really didn't want to have to hone it but if you think it will burn oil maybe then I will.

Worst case is low compression, oil usage, or both. Remedy would be at minimum a hone. Possibly a bore as well. If nothing is loose in the area (obviously it isn't, you can't feel it), I would not believe that it could contaminate or damage any other parts.


I can't see the hatch quite as well at that spot, as I can in the right side of the picture. If the hatch is still present through/around that area; I personally would run it as is.



Your absolute worst case is: Decide you need to take the engine out again. Lightly skim the head (at least have it checked again), bore, hone, rings, bearings (if you like).

What you are gambling with is your own time.



What would work, is putting the head on, torquing it up, then using a starter and a battery to do a compression test on it mounted to the stand. You'll see the numbers, then know if you want to go back in.

I personally do not think it would burn oil any more than normal.




EDIT: OBVIOUSLY do the starter/battery compression test very carefully, with proper insulation for yourself.

That is a good idea. I will check compression/leak down that way

Personally I'd forget I ever saw that and run it as is. Every time I've messed with rings/cylinder walls I've ended up having some kind of issue shortly after. I guess there's just a lot of opportunity for something to go wrong when you start pulling apart the bottom end and for me that outweighs what looks like a relatively minor issue.

Since the bottom end is together, I'd run it too. There is not much to loose really. Just don't be surprised if down the road compression on that cylinder sucks and you will still need a rebuild anyway

That is super light surface rust- it's nothing. Just run it. That happens just from letting a car sit for a few months, it will be gone after 2 seconds of running the engine. 100% not a problem at all.

Whoops, wrong thread.

If you can't feel any big roughness run it as is, it won't be a problem, could be a stain from a nbr. of reasons. The few vertical lines are just normal friction lines from the piston skirts which I guarantee is in every engine to some extent.

Thanks guys. I plan on running it as is for 1 year and then pull the engine and do a na high compression e85 build

I just wanted to point out, I left the cylinders alone and thecar put down 152hp on a dynojet. And it doesn't burn abnormal amounts of oil.