If you are pushing coolant out the overflow while not overheating, that sounds like a bad head gasket. If pressure from the cylenders gets into the cooling system, that is what it will do. It will also have an affect on the heater. Usually it is caused by an air block. Have that checked. As far as the heat, start the engine, let it warm up with the heater on high, and feel both heater core hoses. If both are hot, then you need to check the blend air door. It is near the heater core and determines if you get heat or AC into the vehicle. If it is stuck, that will cause your problem. However, that has nothing to do with the coolant coming out the overflow. With the engine cold, remove the radiator cap and start the engine. If coolant comes shooting out, you have a headgasket problem.
Wednesday, January 12th, 2011 AT 9:53 PM