What Causes the Noise After Engine Shutdown?
2 Answers
Engine noise after shutdown is a normal phenomenon, designed to prevent the engine from "seizing up" due to rapid cooling after stopping. Relevant explanations are as follows: 1. After driving for a period, various components of the engine reach high temperatures. Upon stopping, moving parts inside the engine, such as cylinders and piston rings, crankshafts and connecting rods, may "stick" together due to the high temperatures. This can lead to tightness during the next startup, commonly referred to as "cylinder seizure or bearing failure." 2. After prolonged driving, when you need to park, it's advisable to let the car idle in place for a few minutes to allow the engine temperature to decrease naturally before shutting it off. If the vehicle is equipped with an automatic cooling function, meaning that if the engine temperature is too high after stopping, it will automatically activate the fan to continue cooling the engine. The fan will stop automatically once the engine temperature drops to a reasonable level.
When the engine continues to make noise after shutting off, it's mainly caused by the contraction of hot components during cooling. For example, the exhaust pipe—metal expands under high temperatures and makes a clicking sound as it cools and contracts after shutdown. Additionally, the cooling fan may continue running for a while under computer control if the engine was recently operating at high speeds or the ambient temperature is high. The turbocharger might also produce a slight hissing sound during cooling. These are all normal phenomena and nothing to worry about. However, if the noise persists for too long or sounds particularly unusual, it's necessary to investigate—possible issues include a faulty fan motor or poor contact in the circuit relay. During regular maintenance, checking the exhaust system fasteners and fan motor can prevent future problems. After all, minor noises don’t affect driving, but ignoring potential faults can hit your wallet hard. I’ve replaced many parts myself—the key is observing regularity.
