something got in and caused these scratches. can/will they cause blowby if reused?

piston damage

I figure if the placement of its .018 mil piston ring gaps matter, then the gaps from these scratch just may as well. I already took off any high spots. and could cut the grooves again if need be.

of course new is usually better, but I'd like to determine if it is at all reasonable to reuse this piston.

  • Are there scratches or gouges in the cylinder walls?
    – CharlieRB
    Commented Aug 18, 2017 at 13:21
  • luckily not a one
    – axa
    Commented Aug 18, 2017 at 17:11
  • How did you determine there was no wall damage? Did you just eyeball it, or did you do the proper measurements for taper and out-of-round? Was there a ring ridge? How much slop is there between the piston and the wall? It has always been my approximation that if you are going to do things, do it right the first time that way you don't have to do it twice (or more times). Commented Aug 18, 2017 at 19:32

2 Answers 2


The piston will be fine - it is the rings that provide the seal with the bore. As long as the rings move freely side to side then it will seal as it should.

If the rings stick then that should be addressed.


The foreign object damage to the piston means there is very likely similar damage to the bore . New rings can not fix that problem.

  • oddly or lucky enough there was no wall damage at all. perhaps that means the hardness of what ever feel in was somewhere between aluminum and the sleeve alloy. that said it'll be honed for a cross hatch
    – axa
    Commented Aug 18, 2017 at 17:05

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