Why might my 97 Cavalier be running hot?

IAMCOOL_315

MEMBER
1997 CHEVROLET CAVALIER
120,000 MILES

I have changed the thermostat, water pump, and cap with no luck. The reservor and top radiator hose boil and the bottom hose stays cool. Maybe new thermostat is bad

Tuesday, January 17th, 2012 AT 4:46 PM

3 Replies

CARADIODOC

MECHANIC
33,727 POSTS

Radiator could be plugged but a leaking head gasket would be more common. If you see that boiling right after the engine is started and obviously not warmed up yet, suspect the head gasket. The clue is there won't be any steam associated with that bubbling. The air will form a pocket under the thermostat and prevent it from opening. Thermostats open in response to hot liquid, not hot air.

Your mechanic can perform a "sniffer" test to check for a leaking head gasket. Air is drawn from the radiator or reservoir through a glass cylinder with two chambers partially filled with a special dark blue liquid. If combustion gases are present, that liquid will turn bright yellow.

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Tuesday, January 17th, 2012 AT 4:57 PM

IAMCOOL_315

MEMBER
2 POSTS

When I get the air bled it take about twenty min for it to get hot and it does steam when it's boiling. Also, I can squeeze the bottom hose and push water out the top hose, think I should try taking thermostat out and see what happens?

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Tuesday, January 17th, 2012 AT 5:07 PM

CARADIODOC

MECHANIC
33,727 POSTS

Removing the thermostat won't magically fix anything unless it is defective or air from a leaking head gasket is causing it to stay closed.

Be sure the electric radiator fan is turning on when the engine gets hot. If it is, the head gasket check should be done. Rule out the most common cause before you go searching for other less likely causes. If the fan is the problem, the lower radiator hose should be hot too.

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