Closed Thermostat

[BigNiner19]

Got an early 1990's Johnson 60 HP. Got a new water pump and thermostat recently and changed out the old with the new. Water pump seems to pumping good, and the thermostat definitely made the motor shoot out warm water as opposed to cool water from not having a thermostat in it before.

However, the thermostat is staying closed...and after running wide open throttle for a few seconds my buzzer will come on, so I have to shut off the motor. Without the thermostat in it, this never happened. I took the new thermostat and tossed in a pot on the stove and heated up the water, and the thermostat opened up. Granted, the water probably was a little hotter than 140* as the water was close to boiling, but I did'nt have a thermometer....so I just wanted to check to make sure that the thermostat would open and close. Any thoughts or suggestions? Any shot, that my new water pump could be making my buzzer come on?

Cory

 

[ob]

Re: Closed Thermostat

Those T/stat assemblies have a spring loaded bypass feature which allows them to lift off of their seat when engine is operated at higher rpms ,bypassing the thermal actuated valve portion.Insure that you used the correct spring for the application you have.There have been some factory changes with respect to the cooling system which in your case could include the use of a different spring and or doing away with the overboard flow restrictor and just inserting the rubber hose through a grommet installed in the lower engine cover.One other thing you can do to confirm whether there is indeed an overheat condition when the alarm sounds is to obtain a 163 degree thermo melt stik from your dealer and mark or simply touch check several locations on the engine heads and block.Normal running temps for that engine should remain in the low to mid 150 range.A good indicator of whether the bypass feature is operating when engine is up to speed is to monitor the water discharge from the two exhaust relief holes on the upper rear of the midsection while underway.

 

[BigNiner19]

Re: Closed Thermostat

thanks for the reply and information. I've got some work to do to figure this out I suppose. I was given two different springs in the kit for the thermostat. A cone shaped spring, as well as a more "cylinderical" shaped spring. I was using the cylinder shaped one as it seemed to fit inside nicely.

Cory