johnson 25 overheat

[Skidooosl]

I have a 1978 25 hp johnson on my pontoon, we were just crusing slow, 2000 rpm and failed to notice it was not pumping water ( has a new impeller and everything, also noticed some water comming out of the exhaust ports but no stream was shooting out the motor ). It sputtered and died,cranked it over and nothing. Upon checking the motor it was very HOT. Is there a over heat sensor or did I Smoke something. I just towed it home and parked it, next weekend I will pull it off and check compression and try it again, any ideas?

 

[OBJ]

Re: johnson 25 overheat

Your t-stat probably went south Skidooos. It's under the head cover. You have to remove about 13 bolts, I think 13...it's a bunch, to get the cover off. Yes there is a heat sensor. It's in the head. It'll have a single tan wire coming from it. Chances are your warning horn has gone south also. Heres' how to check.<br /><br />At the engine, pull the rubber boot back on the tan sensor wire to expose the knife connector. Turn the key just to on and ground the harness end of the tan wire. The warning horn should go off. Steady tone. If it don't, trouble with the horn. If it does, sensor is bad. If the sensor is bad, replace it while the head cover is off.<br /><br />You did right right by leaving the engine shut down and towing it home. Hope compression is good.<br /><br />Keep us posted.

 

[haywire]

Re: johnson 25 overheat

I have a 35hp 2000 is water supposed to be coming out the exhaust port next to the p hole while running? I dont. The water from p hole is that to be warm or cold?

 

[Mas]

Re: johnson 25 overheat

I have a 35hp 2000 is water supposed to be coming out the exhaust port next to the p hole while running? I dont. The water from p hole is that to be warm or cold?

Haywire, start a new post!

But, the tell-tale temp will probably be cool at idle and warm at WTO. If it is cold, you may have a thermostat issue. Use an laser thermometer and monitor the head temp to confirm.

MAS