WOT cuttout with very hot heads

[ezdiver75]

i have a 1998 johnson 60hp oil injected and all of a sudden wot cutout. started back up but could not run wot without shutting off. Next time it cutout I had to wait about 15 mins before it would start then I had to limp back to port. I have read all these posts but my problem is different in that I can't touch the heads, seems to be overheating. No horns or anything, pissing plenty of water, was wondering if the thermostat could be the problem?

Most of the electronics , powerpack were replaced 3 years ago and the boat wasn't used for a season and a half.

I have a clymer manuel but I am going in circles because of the overheating heads.

any help would be greatly appreciated

Tom

 

[tashasdaddy]

Re: WOT cuttout with very hot heads

it sounds like the classic overheat. test you sensors. i it was pumping water, the tstat, must be stuck closed. check your compression before anything else.

 

[ezdiver75]

Re: WOT cuttout with very hot heads

thanks, i will try that

 

[ezdiver75]

Re: WOT cuttout with very hot heads

well i did a compression test and it was only about 85psi per cyl. they are all the same just don't know why so low. I also tested the sensor harness and the horns worked fine(but never sounded during my cutout) I think maybe the temp sensor might be bad in addition to the thermostat.

just don't know

 

[Silvertip]

Re: WOT cuttout with very hot heads

85 PSI is telling you the engine does not like being continually overheated. Regardless what you do now, do not expect this engine to live very long as its been overheated one or two times too many. Just because its pumping water does not mean its being properly cooled. Bad thermostat, stuck poppet valve, ignition timing too far advanced, and lean carburetion will all cause overheating.

 

[ezdiver75]

Re: WOT cuttout with very hot heads

that's what i thought. now i have to find out how much a rebuild is gonna cost me. Guess my season is over

 

[reload]

Re: WOT cuttout with very hot heads

You won't know til you get it apart.

 

[hoeser]

Re: WOT cuttout with very hot heads

You should be able to finish out the season at 85psi.

 

[Silvertip]

Re: WOT cuttout with very hot heads

The season is not necessarily over. Fix the overheating problem. The engine will run with 85 PSI compression. It will just be a little down on power. However, if the cylinders have been scored, THEN your season may be over as you will only continue to increase the damage. Pull the head and check the cylinder bores. If they are ok, replace the head gasket and button it up. Replace the thermostat and poppet valve and give it a whirl.

 

[ezdiver75]

Re: WOT cuttout with very hot heads

thanks guys.

i just replaced the vernotherm that was welded shut and the temp sensor that was bad, probaly why i had no alarms. i have a head gasket coming tomorow.