How does the radiator coolant overflow tank work?
The radiator coolant overflow tank saves you money by preventing rust in the car's cooling system. When the engine is operating at its optimum performance, engine coolant is required to maintain it within the operating temperature range. Engine coolant absorbs heat from the engine. As the coolant heats up in the radiator, it begins to expand, causing an increase in pressure in the cooling system of the vehicle. When the coolant pressure in the radiator exceeds the pressure cap setting, the coolant is sealed through the pressure cap and flows through the overflow tube into the radiator coolant overflow tank.