WHAT CAUSES A RADIATOR TO OVERHEAT? | EHOW.COM.
Don't open the radiator cap of an overheated car. When it's cool enough to open, use Overheating rapidly leads to expensive consequential damage. There is no radiator cap on the Northstar engine. The only cap is on the surge tank (or expansion tank) and is pressurized. Best Answer: The radiator cap has a psi rating on it. It is designed to be air tight and allow a pressure build up in the radiator. One problem that has been known to cause overheating is the radiator core. Why is a car overheating even after changing the water pump and the radiator? A bad radiator cap may cause overheating and corrosion to the system as well. The boiling point of coolant is raised by adding pressure to the system. 1. RADIATOR CAP: The cooling system of an engine is designed as a sealed system with the engine coolant held under pressure. Do not open a hot radiator cap. If your coolant gets excessively low, you run the risk of overheating your car's engine and causing internal damage. General Subaru Tech Forums gt; New Gen.: Legacy, Outback, Impreza, Forester, WRX, etc I figure I have a plugged radiator, but not sure. Best Answer: You can get a radiator cap at any hardware or auto parts store.