Thermostat operation

[ianyoung77]

I have pulled the thermostat from my 1990 50DETO (Australian) motor. My Clymer manual tells me to test to the temp written on the thermostat flange. I can't find this temp. It opens at 120F and opens at least 3mm. Does anyone know what the correct temperature is? As the thermostat is 15 years old should I replace it anyway? It had some crust on it but no pitting and seems to clean up ok.

 

[panacea]

Re: Thermostat operation

Hey, Ian, you gave me a good tip on the oil sensor, maybe I can help you here. The normal temp after warm-up at idle for outboards is 125 and at WOT 163 approx. give or take a few degrees. So your temp would most likely be in that range. You can test your thermostat by holding it in water in a pot which you slowly bring to a boil. It should start opening up right when the bubbles start forming and be completely open when it reaches the boiling point. Since yours opens 3mm this seems to be ok.