Originally Posted by
Revo-lution
Glow plug detonation. That's why the damage is at the top of the piston wall and not the bottom where a bearing scrap would have gotten it.
What is "glow plug detonation"?
Detonation is premature burning of fuel and air mixture. To fix that problem he could/should have changed a head shim or used a different plug (heat wise).
The damage on the top of the piston and down the sleeve is from a up stroke of the piston catching a fragmented piece of metal in a port. Seen that more then I'd like to talk about. The pitting on top of the piston could and probably is from detonation or some like to call it "pre-det".