What Are the Symptoms of a Faulty Car Radiator Cap?
2 Answers
When the car radiator cap is damaged, coolant will spray out from the radiator cap, reducing the flow of coolant into the engine and lowering the pressure. The heat generated by the engine cannot be carried away by the coolant, leading to engine overheating or even boiling. Here are the related details: 1. How the car radiator cap works: The car radiator cap has two layers, with a valve core in the middle. The valve core is equipped with a spring and blocks the filler port. There is a passage above the valve core connected to the overflow tank. When the radiator pressure is high, the water pressure lifts the valve core, allowing coolant to flow into the overflow tank. The valve core also has a one-way valve. When the radiator is low on coolant, the one-way valve opens, allowing the coolant from the overflow tank to refill the radiator. 2. Functions of the radiator cap: (1) Sealing. Under any operating condition, the radiator cap must prevent coolant from leaking out. (2) When the coolant temperature rises and the radiator pressure increases to a certain level, the radiator cap automatically opens the pressure relief valve, allowing excess coolant to flow into the overflow tank due to thermal expansion. (3) When the coolant temperature drops, the radiator forms a vacuum due to the coolant's contraction. The radiator cap automatically opens the return valve, allowing the supplementary coolant from the overflow tank to flow back into the radiator.
After the radiator cap broke, I noticed the car was prone to various issues, such as frequently seeing coolant leaking from the radiator opening, especially noticeable after stopping from long-distance driving. The engine temperature would rise rapidly, and the dashboard coolant temperature warning light would come on. This is because the cap couldn't maintain system pressure, lowering the coolant's boiling point and making it prone to boiling, producing hissing or boiling sounds. Sometimes, I could smell the sweet scent of coolant or noticed that the coolant was being consumed too quickly, requiring frequent top-ups. If not addressed promptly, the engine could severely overheat, leading to cylinder head deformation or damage, increasing repair costs. I personally recommend regularly checking the cap's seal and using simple tools to test if the pressure valve closes properly, ensuring driving safety and avoiding unexpected failures.
