motor seems to run hot,then dies

I have a 1987 evinrude outboard-15hp 2stroke
at trolling speed it runs great for a while but then it will puff some smoke toward bottom of shaft
and die....
at this pint it is very hot and once cooled down will restart, then have to open up full throttle to clear to
get it to smooth out again
i felt the water that is flowing through engine after it is evacuated and it's very very hot
anyone have any ideas.....
i have not inspected water impellar bot flow does not seem to be restricted
thanks

Re: motor seems to run hot,then dies

You may have a weak impeller. Anything above idle speeds it cools fine, but at idle, it won't pump enough, and usually would be exposed by intermittent/no indicator stream at slow idle. When you rev it up, it starts pumping, and the water will be scalding at first. If you have a steady indicator stream even at low idle, you may have a faulty thermostat stuck closed, or an obstruction in the water path from pump to discharge. Good luck, and welcome to iboats!

Re: motor seems to run hot,then dies

water intakes clogged, impeller needs replacement, water pump body air vent clogged,lower water tube grommet collapsed or water tube partially displaced, water tube upper grommet collapsed, restriction in cooling passages, thermostat stuck, exhaust gasses entering the water jacket, etc. I know this sounds like a smarta** answer...if you haven't already done so..google..leeroy's ramblings..outboard maintenance and repair..9.9/15 hp....it'll show you how to remove the lower unit and access the water pump/impeller...as well as the location of the thermostat and countless other things having to do with this series of engines....Welcome to iboats!..first time doing anything to these motors seems a little daunting, but dig in..post back with results and someone will have ideas on ways to proceed..an official OMC workshop manual is the best tool to begin with

Re: motor seems to run hot,then dies

kbait said:

You may have a weak impeller. Anything above idle speeds it cools fine, but at idle, it won't pump enough, and usually would be exposed by intermittent/no indicator stream at slow idle. When you rev it up, it starts pumping, and the water will be scalding at first. If you have a steady indicator stream even at low idle, you may have a faulty thermostat stuck closed, or an obstruction in the water path from pump to discharge. Good luck, and welcome to iboats!

Click to expand...

thanks for info I think I'll try impeller replacement first

Re: motor seems to run hot,then dies

I've found over the yrs that if you have an over heat prob, you go for the throat first, and that's the water pump. After that if you still have a prob, look for something else.

Re: motor seems to run hot,then dies

Your water pump/impellar is the heart of your motor.
A hope you did not fry that motor.

Re: motor seems to run hot,then dies

I would replace the impeller and the thermostat. These are both the typical issues that cause cooling problems and are the two main items to replace, for proper maintenance on those motors. Kinda like doing points, plugs and condensors to renew your ignition system.

Re: motor seems to run hot,then dies

There is usually a round cavity under the plates that the pump sits on where water circulates before getting pumped through up to the motor. Make sure this is clean and free of any build up. Had a mate who went through the trouble of replacing the impellor, but too lazy to lift the plates and replace the gaskets. When i was given it for nothing, I quickly took it apart and the cavity underneath the plates was choked with crap. My mate though it was clear by shoving a wire up the intake LOL. If you are going to take it apart for the impellor, inspect everything, then clean and replace. Not sure on your model but I replaced the gaskets and cleaned the plates till they were spotless as well as the impellor.