grey goo and debris on piston

[mball2301]

I bought my 2000 XP 5 years ago with 160 hours on it and have put at !east a 100 more hours on it. This year it died. When I pulled the head off, the piston in front is in great shape and looks fine and the other one has grey goo on the center of the head and what looks like aluminum melted debris around the edge of the piston and the head. The cylinder walls look fine. I am in the process of pulling the engine and will try to post some pics. Any idea what the failure was?

 

[AdamXP800]

Does your ski have the original grey tempo fuel lines?

 

[mball2301]

Until this year it had the grey lines.

 

[AdamXP800]

I would say detonation and it melted the piston crown