Expansion Tank Caps

Expansion tank caps maintain system pressure within the engine coolant reservoir, preventing vapor lock and coolant loss. These caps are used on vehicles with closed-loop cooling systems and feature a pressure-relief valve calibrated to a specific PSI rating, ensuring safe operation. Construction typically includes a reinforced thermoplastic or metal housing with a nitrile rubber seal for leak-proof performance. Variations exist with integrated vent ports or different pressure ratings based on vehicle application. Proper cap function is critical for maintaining optimal cooling system efficiency and preventing overheating. Failure can result in coolant loss, temperature gauge inaccuracies, and potential engine damage.