Why is there a ticking sound after the car is turned off?

[VanGrace]

Generally, the reasons for abnormal sounds after the car is turned off are as follows: 1. Uneven cooling of the engine. After driving for a period of time, the engine temperature is high. When turned off, the temperature of various components decreases, and thermal expansion and contraction are not uniform, causing friction between metal parts inside the engine due to cooling contraction, resulting in abnormal sounds. 2. Turbo cooling sound. Under normal circumstances, the exhaust gas temperature reaches 600-700°C, accelerating the temperature generated by the rapid rotation and friction of the turbo. After turning off, thermal expansion and contraction are also very noticeable, leading to abnormal sounds. 3. Exhaust pipe cooling sound. Typically, the exhaust pipe temperature during cold idle is around 200 degrees. When the car is under high load or there is a mixture burning in the exhaust pipe, the temperature will be even higher. Therefore, the exhaust pipe also undergoes thermal expansion and contraction, producing abnormal sounds, often originating from the front end of the exhaust pipe and the flexible connection area.