Why is there a boiling water sound after the car is turned off?
1 Answers
After the car is turned off, the water pump also stops, and the entire circulation system ceases to function. However, components like the engine remain very hot, causing the water to absorb heat and evaporate, leading to volume expansion. This pressurized water is then forced from the radiator directly into the overflow tank. If there is too much water in the overflow tank, the excess water will overflow, releasing the characteristic sound. Below are the specific reasons: 1. Turbocharged engines equipped with an automatic cooling system after shutdown: After turning off the engine, if relevant sensors in the engine bay detect that the engine temperature is too high, the temperature signal is fed back to the ECU. The related control system will issue commands to automatically activate the oil pump, liquid cooling system (resulting in the sound of coolant circulating), and even the cooling fan to lower the engine temperature. Once cooled, all cooling systems will automatically shut down. 2. Turbocharged engines without this system: If a turbocharged engine lacks this system, the cooling system will not continue to operate after shutdown. Once the engine is turned off and power is cut, none of the cooling systems can continue to function. Therefore, for turbocharged engines under the second scenario, it is necessary to idle for 2-3 minutes before shutting down after high-speed driving. This allows the cooling systems to continue operating and cool the engine.
