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LS2000 Melted Piston

jkorotki

Member
Messages
1
Reaction score
0
Points
10
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.
 

tdonoughue

Jetboaters Admiral
Messages
3,800
Reaction score
2,745
Points
302
Location
The Woodlands, TX 77381
Boat Make
Yamaha
Year
2012
Boat Model
AR
Boat Length
24
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.).
 

4x15mph

Jetboaters Captain
Messages
1,812
Reaction score
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Points
237
Location
Downingtown, PA
Boat Make
Yamaha
Year
2018
Boat Model
AR
Boat Length
21
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
 

the MfM

Jetboaters Commander
Messages
1,057
Reaction score
1,109
Points
197
Boat Make
Yamaha
Year
2000
Boat Model
LS
Boat Length
20
I’d check the rear main (crank) seal
 
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