The engine radiator cap is a critical component of a vehicle's cooling system, designed to maintain optimal pressure and temperature levels within the radiator. Key features of a radiator cap include:

1. Pressure Rating: Radiator caps are typically rated to withstand specific pressure levels, usually measured in pounds per square inch (psi). The pressure rating ensures that the coolant remains under pressure, raising its boiling point and preventing it from boiling over at higher temperatures.

2. Sealing Mechanism: Radiator caps feature a sealing mechanism, such as a rubber gasket or O-ring, which ensures a tight seal between the cap and the radiator neck. This seal prevents coolant from leaking out and air from entering the system, maintaining system integrity.