Overheated... now what?

[dgohmann]

1989 Mercury Outboard, 4 cyl, 100 hp<br /><br />Running WOT, I stopped for a minute to allow some passengers to change seats, and then I punched it, seconds after that the overheat alarm came on and I quickly pulled back to neutral and shut down the engine. I got a tow back. I later tried to restart the engine, it fired right up and is running ok. Water is coming out the back so I know the impeller is ok. The next morning I started it again, this time it was a cold start and usually there is a cloud of smoke, this time no smoke at all. This engine still has oil injection, but I am assuming that if the oil injection has failed I would have already seized the engine by letting it idle for awhile and revving it briefly to 2 grand. Anyone have any ideas on what may have happend? I am still planning to take it to the dealer, I am just looking for some new food for thought.<br /><br />Thanks<br />Dan

 

[Kenny Bush]

Re: Overheated... now what?

Take a marker and mark the current level of the oil tank, and also put some two stroke oil into the gastank(estimate 50:1) and continue to run. After a couple of hours, see if the oil in the tank has dropped any. If you do not see it drop after a few hours, you probably broke the plastic oil drive gear in the motor. You should be OK with the premixed tank, and if your oil injection is working, it will smoke quite a bit more. I am still a little up in the air about the overtemp alarm.

 

[paulgp6022]

Re: Overheated... now what?

The overtemp alarm and low oil alarm share the same buzzer. If you have water out of the tell tale, then I suspect it is oil related.

 

[dgohmann]

Re: Overheated... now what?

My oil sensor was disconnected years ago because it was crushed when the tank collapsed becuase of a bad cap. The alarm that went off was overheat (solid tone). The oil alarm has no way of going off anymore.<br /><br />My only guess right now is that the oil injectioin failed and caused the over heat, but then why won't this engine seize up? As I said it has started on two separate occasions later in the day, but not run anywhere.<br /><br />Or how bout this - if when I stoped a bunch of loose weeds could have blocked the intake hole, but if that was the case I would have destroyed the impeller upon throttling up wouldn't I?<br /><br />Dan

 

[dgohmann]

Re: Overheated... now what?

BTW I do have a temp gauge and it was maxed out at 220 F when the alarm began to sound. When I opened the engine cover there was a little bit of smoke, so there really isn't any doubt in my mind that it overheated.<br /><br />Dan

 

[CU2NITE]

Re: Overheated... now what?

I would first check compression to see if all is good there. If it is I would plug the oil system and pre-mix. These older mercs are bad about the oil system failing. Also because you did over heat you may want to check the impeller also. Good luck and let us know.<br />CU