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Q: My radiator is full and my overfill is full yet my car still is overheating.

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My radiator is full and my overfill is full yet my car still is over heating. I just had a new radiator and thermostat put in. Why is it still overheating?

My car has 178000 miles.
My car has an automatic transmission.

Hi there. First check the reservoir cap and make sure that it can hold the pressure that it says on it. If the cap can hold the pressure, then either the water pump is not working or the engine has a blown head gasket. To check the head gasket, get a block tester from a local parts store and put it together with the blue chemical in it. Remove the radiator / reservoir cap and start the engine. When the water is getting warm, there will be steam coming out of the neck. Take the block tester and use it to suck up the steam vapors only. If the blue fluid turns green or yellow, then combustion gasses are getting into the cooling system. This would indicate a blown head gasket, cracked cylinder head, or a cracked block. If you need further assistance with your engine overheating, then seek out a professional, such as one from Your Mechanic, to help you.

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