Thermostat

HEYMAN764

MEMBER
1973 CHEVROLET CHEVELLE
5.7L
V8
2WD
AUTOMATIC
34,320 MILES

Hi, the thermostat in my car likes to open and close very loudly once I shot the car off. The car does not overheat but after a good drive on the highway, I will shut the car off and thermostat will open and close about five times. The thermostat is a new high performance Mr gasket 180 degrees high flow. Could the thermostat be faulty?
Thanks

1 Reply

STEVE W.

MECHANIC
12,972 POSTS

I would not run it if it is popping open/closed, It should not make noise. It could cause a problem if it also works that way when the engine is heating up while you are driving. The thermostats job is to control coolant flow and provide some flow restriction to allow the radiator to do its job. The high flow units can be a problem because they do not restrict the coolant enough and you get steam pockets in the heads.

Being that you installed a low temperature version (OEM = 195 degrees) it will make the problem worse because it opens/closes at the lower temperature, the hunting that you hear is because the engine is not being cooled and the thermostat keeps opening as the coolant heats back up from the residual heat in the engine.