I am hoping that someone can answer this. If the skirt of a piston has been rubbing on the cylinder, does it make the piston garbage? When I disassemble my engine for an overhaul, I noticed the pistons were worn on the skirts. There was no dissernable problems before, besides a small knock which is what prompted the rebuild (plus it has 70000kms on the clock). When I measure the diameter of the pistons, they are still larger where it is worn than other spots. Since rings do all of the sealing, what are the drwbacks to using a piston like this? This is a pretty technical question, but hopefully the answer will save me some grief, either now or later.