Need 2nd Opinion Please

[jshall]

Hi Guys- I would like to run something past everyone here. Late last summer, my 1985 Johnson 235 overheated and blew the head gasket on the starboard side of the motor. My mechanic took care of it. The head was machined, but otherwise ok. As a precaution replaced the other head gasket as well. He mentioned the water diverters on the overheated side were damaged and repaired/replaced them. Also, new thermostats in the process. Yesterday, I was cleaning up some things and flushing the motor. With the cover off, I noticed the starboard side (side that previously overheated)) was hotter than the port side. It was not an instant condition, but didn't take along time either.I could hold my hand for about 10 seconds on the cooler side and only about 3 on the hot side. I was putting my hand directly on the thermostat cover. Warning buzzer never went off. I removed the thermostat completely from the hot side and retested. It all felt fine. My mechanic suggested removing the guts from a thermostat and replacing them, effectively leaving the thermostats in a "stuck open" condition.
He went on to say that doing this rather than no thermostat at all, allows the water to remain inside the motor long enough to actually cool it, while in some cases with no thermostat, the water doesnt cool the motor at all because it passes through so quickly, particularly on the exhaust side.

So there's my question- Anyone else feel this way? I had always thought with no thermostats, the motor would never reach operating temperature, and cooling would not be an issue. I'm in South Florida where water temperature, particularly now, is running about 80 degrees.

Thanks for any info and opinions.

 

[tashasdaddy]

Re: Need 2nd Opinion Please

you are correct about the stats, do not run with out them. did you check the stat in a pot of water. suspend the stat in a pot of water on the stove. using a candy thermometer, watch at what temp the stat starts to open, and when it is fully open. should start atleast by 140* and be completely open by 160*.

 

[mikesea]

Re: Need 2nd Opinion Please

We did the thermo gutting on alot of the crossflows like you have here in the Keys.I recall it being common that one side get hotter due to the way cooling flows.If you have a good impeller,no salt build up you should be ok.I would gut the thermo to help.I would be curious if the thermo was operating ok.The fl.salt is tough

 

[Dhadley]

Re: Need 2nd Opinion Please

Agreed. Removing the t-stats isn't that great of an idea. Running in Fla's warm water with gutted T-stats seems to work OK. Just be sure to gut it or put in a new one, don't remove it all together. The negative is that if the motor happens to end up in cooler water then it may - may - pose a problem.

The starboard side does run hotter on crossflows. But, since the horn has never went off you may still be within the correct operating range. You'll only know after you check it with a thermal gun. And it probably cools off at a higher rpm anyway.

 

[jshall]

Re: Need 2nd Opinion Please

Hey guys-
thanks for all the feedback. I did test the old tstat per tashasdaddy recommendation, and it appears to be working. I had bought a new tstat and checked them beside each other, and the old mirrored the new. So I guess my next question would be concerning causes that if the tstat is working, why would the tstat housing be so hot to the touch on one side? I guess I need to get some thermo sticks and check the temperature on that side of the engine.

 

[Benny1963]

Re: Need 2nd Opinion Please

correct and run a comp check if ya warped a head you may have hurt something i did same thing

 

[Dhadley]

Re: Need 2nd Opinion Please

I'm not sure why the starboard side runs hotter but we've theorized that it may be trapping air at the top of the block & maybe the head. We do know that once you vent the block it cools down, the starboard side doesn't coke up the pistons as much and you don't lose the water cooled regulator / rectifier (if you have one).