noise from thermostat

[chompin]

yamaha 85 HP
is it possible that thermostat making noise like some kind of pulsation ?.

[boats.net]

I have never heard a noise from thermostat area, the water pressure is around 10-25 lbs at thermostat probably not enough to pulsate. If the engine is overheating to the point of boiling water(220 degrees) it might but you should notice that.

[Ken]

chompin,
The thermostat is relatively easy to remove and inspect to see if the center of it has come loose from the coil - but even so, it is hard to imagine the thermostat making a rattling noise.
You might as well test it while you have it out. Heat it in a pan of water and using a thermometer, see that it is fully open at around 135 degrees - about 0.120 inches.
Use a new gasket when re-installing the thermo cover, and be sure to use a thread sealer on the bolts - I like Permatex 14A with Teflon, inexpensive and smells great [img]smile.gif[/img] [img]smile.gif[/img] ,
Ken K