I'm looking at buying a 10 year old Yamaha 90 two-stroke with 150 hours. It has had annual service and the the seller has stated he has never had a problem with the engine except for: when running skinny with his jack plate up he has had the high temp alarm go off twice. He said he let the motor cool down and started back up with no problems. How much do these over temps hurt an engine?
had a Yamaha get hot enough to melt any plastic in contact with the block ...Including oil filler plug ... changed those parts ... motor still going strong ...
I'm no mechanic but I would assume the alarm is set to go off before damage is done. Therefore if he truly shut the engine down immediately and let it cool down it should be ok (theoretically). I would ask if "both" times the alarm went off was it the same trip? If so, he may have been impatient and not let it cool down enough and may have done damage. Probably best to take to a mechanic tell him what you were told and get a professional opinion.
If the motor was shut down when the alarm went off there should be no internal damage. Watr pump may need to be replaces. Do a compression check to make sure everything is okay. Or pay the $60-$100 depending where you take it and let them give you a clean bill of health on the engine.
