Engine Overheated - Now What?

[boatgrunt]

1994 Merc 5.7 with Alpha I drive - While trolling last night in salt water, the engine temp alarm went off. The temp appeared to be around 190/200. I quickly increased my speed and brought the temp back to normal. I ran the boat the rest of the night (about 3 hrs) without any problem.

Have I done any damage? I know from another thread I just posted that salt crystalizes around 180, so I'm going to run some Salt-Away through the engine tonight. Anything else that I should be concerned about or check?

 

[Don S]

Re: Engine Overheated - Now What?

Don't Panic! ! !

You haven't done any damage, and for no longer than it was at that temp isn't a problem. The prolonged running and never flushing while running over 180 is the problem.
How old is that impeller? Are you runniing a raw water cooled system? If so, you might check the thermostat. You should have a quality marine thermostat not an automotive one.

 

[boatgrunt]

Re: Engine Overheated - Now What?

Thanks Don - My temp gauge's normal reading is 170, and I monitor it frequently when on the water. I checked on the Crownline.com board, and it sounds like the rest of the owners with my boat/engine run at 170 per the gauge. I flush the engine for about 15 minutes after every use. The impeller was changed during winterization maintenance last year. I do have a marine thermostat, but the engine is raw water cooled, so I guess I'll pull the thermostat this weekend and check it.