Today I got my '71 Johnson 100 HP (100ESL71C) motor running. Cleaned and re-gapped points, cleaned rotor and cap and did some misc other stuff. Engine fired up and idled well, though a little smokey (has not run in at least 2 years).<br /><br />I was running it with muffs on. Ran the motor at idle for maybe 1-2 minutes. Shut it off immediately when the overheat alarm came on and left the muffs flushing the coolant system while it sat. Touched the cylinder wall and head and could hold my hadn there for just shy of 2 seconds before pulling away to avoid pain. Wish I had an actual temp gauge.<br /><br />What damage may have been done from this, if any at all? How hot should an outboard engine run? All my experience with boats is with 4 stroke cycle inbopards and I/O's. Last outboard in the family was when I was a little kid so I knew next to nothing about it... Only that it ran away if you gave it too much throttle, it sunk once, blew up once, and caught on fire twice and still ran like a top when we sold it.<br /><br />Anyhow, what should I check after this overheat? Also, I have found where to get an impeller but I also want to change the thermostat in this engine but cannot find a place to get one. Any ideas?
