[hancock1701]

Hi guys,

My understanding is that for a typical front-engined car with the radiator in front and such, the pressure cap would maintain pressure up until a set point and let the coolant overflow into the overflow tank, and draw it back in once the system cools down. There have been a few threads about cooling issues, and from reading many threads, I came to understand that the bleeder valve on our car regulates the pressure and lets the coolant overflow into the expansion tank. So what exactly does the tank cap do, besides being a cap?