Strange looking wear on my 5.9 cylinders

MileHighDart said

There is no ridge around the top at all that I can feel, just discolored around the top (above the top ring). And now that I have the pistons out and I've started cleaning them up, they all look great, ring grooves seem nice and tight. No scratches on the sides of the pistons, even on that number 4 that has a little ding in the top.

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There is a spec you need to measure with a feeler gauge: ring side clearance and can be found in the manual and a lot of reference books. Clean both rings and grooves good before checking. If you clean it up and the old rings meet the spec for ring side, then the new rings will just be better.

You can measure ring side clearance by simply inserting the outer edge of a loose ring (off the piston) into the groove and inserting the feeler gauge. Google 'ring side clearance' and you will find pix to illustrate.

And there are tools to clean the carbon out of the grooves, but you can using the square butt end of an old ring.

Good deal on the ridge and general piston condition!