Seized Tohatsu 15 HP

[Sea Rider]

A friend of mine in a hurry to go out boating purchased on his way to the marina a two strokes oil bottle. Went boating for 3 hours at 1/3 throttle as this horse is used as an aux on a sailboat. After use and before shutting engine off, carb's bowl fuel was consumed. Up to this point everything was ok.

On this weekend outing couldn't rope start the engine, rope housing was removed, when turning flywheel with both hands felt completely seized, didn't have a wrench to move flywheel to check seizure condition.

After engine is on land, was thinking removing both spark plugs, squirting W-40, or 25:1 fuel/oil mix into both plug holes, letting soak a bit and with a wrench turn flywheel nut to try to rotate crankshaft.

The oil purchased was found to be generic motorcycle 2 strokes oil with no TCW no number written on the label. If this oil did not seized the engine during it's 3 hours previous work, why is it seized now ? Any ideas ?

Could it be :

1-Rings seizure ?
2-Rings, pistons, cylinders seizure ?
2-Overheat/friction seizure due to inadequate lubrication between related parts ?

Not Happy Boating

 

[pvanv]

Re: Seized Tohatsu 15 HP

Luis,

You will need to investigate more. Might be oil-related, or might not. May have been improperly-mixed oil, etc. For that matter, since it ran fine, maybe the problem happened after the last run.

 

[Sea Rider]

Re: Seized Tohatsu 15 HP

Paul,

The fuel/oil mix was 50:1 the engine run for 3 hours with no problem whatsoever, the seizure problen was found 1 week later inmediately after the last impecable previous run. Definitively a non compatible 2 strokes motorcycle oil issue.

Update : Problem solved.

Locked engine at horizontal position, removed both plug, squirted 1/4 can of W-40 into each plug hole, let soak all night, next day with wrench turned flywheel nut and bingo, flywheel began to turn. Cleaned W-40 cylinder remains with fresh fuel, got new gas with 35:1 fuel/oil mixture, started engine and run at idle for 15 minutes, went full throttle for 1 minute and engine is purring like a kitten again.

Fuel remains inside cylinder walls must have evaporated leaving unwanted gummy motorcycle 2 strokes left overs which stuck pistons to walls during week days. Lesson learned by owner : definitely, outboards are not motorcycles....

Happy Boating