Water boils at 100° Celsius. That is, at atmospheric pressure. But as the coolant in the car heats up, it expands, building up pressure inside the closed system. That is advantageous, as the boiling temperature increases with the pressure. At 1 bar it doesn't boil at 100°, but at 120° Celsius. That means a pressurised cooing system can dissipate more heat, so its cooling capacity is better.
Of course, there's a limit to the pressure a cooling system can handle. That's why a pressure release valve limits the pressure, usually between 0,5 and 1 bar. The pressure release valve is usually combined with the radiator filler cap. When the valve opens, it releases coolant to the overflow tank.
In time, the return spring of the pressure release valve may lose some of its force. Also, the rubber seal can dry out and crack. Loss of pressure and loss of water will decrease the capacity of the cooling system, resulting in overheating.
If the radiator cap is worn, it will have to be replaced by a cap offering the same pressure valve characteristics. Nipparts offers a wide range of dedicated radiator caps. Nipparts radiator caps are made to OE specifications and are manufactured to the highest quality standards.
Nipparts Radiator Caps
- Made to OE characteristics
- High quality seal
- High quality spring
- Made to OE quality standards