Chevrolet Repair: 1996 corsica v6 3100, head gasket, radiator cap

Question
My brother has been having problems with his cooling system the car will over heat if you are driving or idling. you have no heat at what seems to be normal operating temp as the car starts to over heat all of a sudden the heater will start blowing hot air as the temp drops so does the temp of the air coming out of the heater it will go all most cold then the car will overheat again as the temp gauge starts to drop you will have heat again. He has had a new radiator put in because of a large crack in the plastic part of the radiator. also we have changed the thermostat twice as we were told that it is possable to get a bad one from the factory. we have also changed the cap. it is full of coolent and we seem to have gotten all of the air out of the system. i was told that this car has a valve that when the car is cold it stops the coolent from going to the heater core. is this true and if it is could this be the problem?


Answer
Hi Nathan, No there is not a valve that stops the coolant from going to the heater core. Your problem is that there is air in the cooling system, and is most likely coming from a bad head gasket or cracked head. If this engine was overheated I would bet on a bad head gasket as these heads can take a lot of heat. Run the engine with the radiator cap off and look for small bubbles coming out. This will tell you that you need to replace the head gaskets.

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Have a Great Holiday

Mark