My Mercury Marine 25 HP 2-stroke Serial Number 0G002xxx got hot and shut down the other night when returning to the boat ramp. I didn’t realize why it shit down until I tried restarting it. It wouldn’t even crank - the starter just stalled.

Thank goodness for trolling motors!

After getting the boat home I tried cranking it a couple of revs and it seemed to crank normally.

The water pump impeller is shredded so that is a fairly easy fix. I decided to remove the thermostat to check it out. I was shocked to find that there wasn’t a thermostat under the cover.

I have two questions:
Should this mid 90’s motor have had a thermostat installed, or did some unscrupulous mechanic leave it out when it was serviced in the past? I am likely the third owner of this motor, so I have no history of repairs.

Should there have been some sort of overtemp switch that would have shut down the motor before reaching such extreme temperature?