It can take many hours to cool down and for the pressure to go down. There's also the possibility of a leaking head gasket that leaks combustion gas into the cooling system, although typically that kind of leak will also bleed pressure off rather quickly after stopping the engine. Wouldn't hurt to have the radiator cap tested for pressure. It should release any pressure over about 15 pounds.
Tuesday, May 24th, 2011 AT 7:07 AM