Radiator Cap in Watsonville, CA The radiator cap keeps your engine cool by sealing and pressurizing the coolant inside it. It is designed to hold the coolant in the radiator under a predetermined amount of pressure. Once the pressure reaches maximum. the cap opens its release valve and allows heat to escape. To maintain your cooling system, it is important that the even the smallest components are working properly If you are overheating and coolant is not moving effectively throughout the system, have your service advisor check your radiator cap. A new radiator cap is an inexpensive repair and can prevent future damage Because a malfunctioning radiator cap will cause the coolant to boil and your engine will not get the proper amount of coolant And If ignored long enough, the engine will overheat, leading to costly repairs. From a safety standpoint, there is a slight safety risk, because an overheated engine might leave you stranded. But there is high environmental impact, because leaking coolant is harmful for children, pets and other animals.