removing corrosion from cylinder bores

[ChaosAD]

Im fixing up a bluetop 4age that had a blown head gasket, and realised that there was some water sitting around the piston rings that corroded the cylinder bores while it was sitting around (for about six months).

You can feel the corrosion as it is slightly raised.

I was told to sand it (following the crosshatch pattern) with some wet&dry sandpaper (im using 400 grit) and kerosene but it seems to be taking forever and doing little more than making the bores a bit more shiny.

Has anyone tried this before, and know anything about it?

If I dont get it all off will it damage the rings?

Thanks for your help

[Adamal]

I'd say that the DIY jobbie will cause problems.
Even the smallest displacement in diameter in the cylinder could really bugger your pistons.
I'd recommend getting the block bored out. Probably best to recondition the whole engine, save from getting it together only to find something like a big end bearing has seized. Which I'd say would be a high chance if its been sitting around for 6 months with water in it

[ChaosAD]

Thing is, the bottem end has been reconned. Just that the torque to yeild head studs had been reused for about the 3rd time. head gasket diddnt 'blow' it just leaked.

[70ke25]

ok can either strip the engine right down and give the cylinders a light hone, then soak it in warm soapy water that gets rid of all the grindings for a couple of minutes, then grab a clean rag with some oil on it and wipe the cylinders out till the cylinder is clean P.S use heaps of oil
or
you can just get a clean rag with heaps of oil and try wipe your surface rust off, as oil is a rust preventiative!
enjoy

[ChaosAD]

Oil is a rust preventative, not remover. So that wont work.

Not to keen on stripping it back down, only as a last resort. will sanding it not work?

[fivebob]

Sanding it without stripping it down first will leave small amounts of the abrasive from the sandpaper in the bores, this will quickly destroy any remaining ring seal that you have got. Sanding by hand will also leave a poor surface on the cylinder and the bore will not be round at that point. It would be better to use one of those plastic scouring pads, at least that won't damage the bore.

The motor really needs to be stripped and honed at the very least, if the rust has pitted the bore then it will need reboring to the next oversize available.

[evil_si]

if it is pitted it will have to be honed properly even then i'd have my doubts as to it usability, sanding wont be very effective, and a bottle hone probably wont remove it very effectivly,

use heaps of kero if using a hone either use the drill at the slowest speed or if it doesnt go slow enough just move it in and out very fast.

i can acid dip parts at my work which is usally very effective, but it would have to be bare blocked and then reassembled from scratch, which i can do