Radiator caps and expansion caps are two important components of the heavy duty cooling system. The radiator cap is usually located at the top of the radiator, while the expansion cap can be found on the coolant overflow or expansion tank.

The radiator cap seals the radiator and creates pressure within the cooling system. As the engine heats up and the coolant expands, the pressure in the system increases. The radiator cap is responsible for regulating this pressure and preventing the coolant from boiling over or escaping from the radiator. A malfunctioning radiator cap can cause the engine to overheat, which can result in serious damage or failure.

Expansion Tank caps, also called pressure caps, perform a similar function. They maintain the correct pressure in the coolant system, usually between 10 and 15 pounds per square inch (psi) (between 0.7 and 1.0 bar). This pressure helps prevent the coolant from boiling, which can cause air pockets in the system and reduce the effectiveness of the coolant. In addition, expansion caps allow the coolant to expand as it heats up, preventing it from overflowing from the radiator or other components.

It is essential to inspect and maintain these caps regularly to ensure they are functioning correctly to avoid expensive engine damage or failure.

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