Rust...in cylinders.

[dikidera]

So because I took off my head in Late Feb and is now June, my attempts to stave off rust in the cylinder walls have failed, most of the rust is superficial, and 80-90% of the cylinder is fine, except one place on Cyl 1where the rust has left a stain of sorts that did not go away, although I have not scrubbed it much.

Question is...how much trouble are we talking about here and what could I use to safely clean off the rust.

[volvolugnut]

I assume you have an aluminum block and the rust is actually aluminum corrosion. Is the 'rust' white or red?
volvolugnut

[vtl]

Mind sharing a picture?

I would rehone it with the Flex-Hone www.amazon.com/gp/product/B002XUL1F8. Managed to rehone my engine with the block still in engine bay. Need to drop the oil pan for that, remove the piston/rods, cover crankshaft and clean everything afterwards with electric degreaser spray (it cleans the pores super-well, leaving no abrasive dust).

Training material recorded on a donor engine before the process has been repeated on the real engine

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[vtl]

I assume you have an aluminum block and the rust is actually aluminum corrosion. Is the 'rust' white or red?
volvolugnut

Alu block has cast iron sleeves. They rust easily unless thoroughly covered in oil.

[dikidera]

I might take pictures tomorrow or the day after. I would say the cylinders are 80 or even 90% rust free, except a few places, mostly nearer the top side, but on Cyl 1, there is a 1.5cm long streak(about the width of a nail polish brush) that apparently was enough to leave a permanent stain.

Now, if the issue will be slightly increased oil consumption, I think I can live with that, but if this will causes a loss of compression...that would suck a lot.

In the meantime, what I did was use the only oil available, which was ATF fluid, and pour some and coat the walls. But later one I am not sure how to properly clean the debree that will inevitably get in between the piston and cylinder wall.

[vtl]

If it is only a tiny spot of rust, cover the piston with paper towel well, oil it, use grit 240 sandpaper to remove the rust. Press it lightly and move it along the existing hone lines. Top of the cylinder is not very important for oil consumption. It is bad already up there in these engines

[dikidera]

I just hope this won't be playing a bad joke on me, but there are two cylinders with a stain, which unfortunately is more corrosion-like as I can feel it catching my nail. Unfortunately I have not the time nor tools to do a rehone, neither the desire to.

Thoughts?

These stains represent like 5% or so from the entire cylinder. I wonder if it will affect compression or even lead to ring failure.

[abscate]

I would run that just as it is.

[dikidera]

I've added a picture with a better angle. The corroded part is felt up and down, it's on the piston thrust axis I believe.

If this won't keep wearing down or even destroy the rings I will run it as is.

In fact I am thinking of attempting to start and run the car like this. If the engine dies at least I'll know and be certain and scrap it.

If it runs and compression is adequate I will use it like that.

[Krons]

If your fingernail can’t catch it I would not worry. For sure forget about color, it is whether it’ll catch/wear rings. Some 0000 steel wool and motor oil would do the trick to smooth any edges.

Once running the pistons will polish it.