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LS2000 Melted Piston

jkorotki

Active Member
Messages
1
Reaction score
0
Points
30
Boat Make
Yamaha
Year
2000
Boat Model
LS
Boat Length
19
Hello all! I melted the #3 piston on my starboard engine. Pretty obvious that it went lean and poof! As I get ready to rebuild the upper half I am curious if anyone has seen this or could suggest some common causes for this to happen. I do not believe it was an oil issue as I am able to watch oil flow directly into the carb. Any help, guidance, and suggestions would be greatly appreciated.
 
Only help I can offer is to Google melted piston. Seems like a common enough thing on auto engines that they do have some suggested causes. Unfortunately, the causes also seem to be all over the map (bad fuel mix, clogged exhaust, bad injector, etc.).
 
Probably an air leak causing it to run lean. I wouldn’t just put a new piston and top end without continuing to figure out the problem. I would also recommend doing a leak down test once you have it back together. Good luck
 
I’d check the rear main (crank) seal
 
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