1987 225 Johnson Thermostats

[Blake0912]

My motor was not warming up at all, would only get to about 110 after running at 4000 RPM for a while ( No more than 80 deg and idle) so I figured my thermostats were stuck open. The Thermostats in my motor were black and appreard to be missing parts they were very light compared to my new ones. I orderd the "Thermostat Assembly" and they are white and come to a point and then screwd into the gasket fitting under the thermostat housing. I started up the motor on the hose today and it was pissing like crazy(15-20PSI Idling) and there was not water coming out of the exhaust relif ports like it used to do with the old thermostats in it. The motor warmed up in about 5 mins on the hose. But the starboard head was running about 15 deg hotter than port. The starboard head was at about 155 deg , port 140ish. Is this normal for one to run hotter than the other? Also I assume that the water was immediatly coming out of the exhaust relife ports with the old thermostats because they were stuck open and the water pressure was much lower at idle (5-10PSI). Now there is not water coming from the relif ports because the thermostats are working correctly? causing the higher water pressure?

I've read that this motor has a thermostat bypass feature after about 2K RPM to insure the motor is getting enough water to cool it down...is this true?

Also what temperature should this motor be running at idle/Crusing speed WOT?

 

[Greg_E]

Re: 1987 225 Johnson Thermostats

Here is some info on the water diverter valve. It is on the starboard side of the motor and is actuated by the throttle control arm. Follow the hose from the starboard thermostat cover. It will go to the valve.
http://forums.iboats.com/johnson-evinrude-outboards/225-looper-cooling-system-177128.html

Inside the thermostat housing is a spring and a vernatherm. The vernatherm has a small piston that is pushes out when the vernatherm is heated, opening the thermostat. The spring puts pressure on the vernatherm to push the piston back in when the vernatherm cools. You can unscrew the two halves of the old thermostats to see what, if anything was inside.

I don't have an explanation as to why one side is 15* hotter at idle.

Sorry I couldn't be more help, but maybe someone else can check in with more info.