i change the head gasket on my regal,i put on all new gaskets and the engine is running great but now the car is over heating.i changed the thermostat and the coolant temp senor and the car is still over heating.i flushed the system well i was flushing the system the car was overheating i looked in the radiator hole where the cap gos.. i Noise the water was circulating throw the radiator so i know its not the water pump.i can see stem coming out of the right side of the radiator can that be a sign of a bad radiator and is that why my car is overheating or can it be a crack block?? thanks