Bazil_SW

iTrader: (4)

hi. I'm in the process of (slowly) rebuilding my forged 2.5 engine. Having never rebuilt an engine before, it's one step forwards and two steps back at the moment!

I've gotten as far putting the pistons back in but notice that there are some cylinder wall scraches, some near the top and some in the middle of the stroke that can just about catch a nail. The engine has 99.75mm Mahle pistons that covered about 14k miles before the headgaskets gave out again. I'm considering that I do not want to replace the pistons, so guessing that a bore would be out of the question, but I think a hone might be beneficial if at least to ensure the surface is a good as it can be with the small scratches there.

Firstly what are peoples thoughts? And also if I hone using one of those 3 pronged honing tools can I reuse the same rings?

Cheers!

MOTORS S GT

iTrader: (2)

I would get the bores measured first, at 14k they will likely be out of round & tapered if its had bit of boost & heat through it.

Bazil_SW

iTrader: (4)

ok, I'm pretty far down the rabbit hole now anyway so I've bought a bore gauge and a suitable micrometer and will see what it looks like.

If it needs boring to fix anything out of spec or for the scratches, then I guess it's check the clearances of the pistons vs the acceptable specs as #1 then check the ring gaps against the acceptable spec also?

Bazil_SW

iTrader: (4)

Ok a little late, but I've checked the bores and they are within spec for out of round and taper - some measurements are slightly over the standard, but all are well within the limits.

The pistons are Mahle (not sure the ring type), but I've read somewhere use a 280 grit hone, which I've done, and targeted a 30deg to horizontal (so 60 degrees to the axis of the bore) angle.

Appreciating it's difficult to say anything for certain from a picture, but generally does this cross hatching look reasonable?

Cheers!