What Causes the Ticking Sound After Engine Shutdown?
3 Answers
It is normal to hear a ticking sound after the car is turned off, and there is no need to worry too much. Here is the relevant information: 1. Most likely cause: The ticking sound occurs because the engine temperature rises correspondingly after continuous high RPM operation, making the engine very hot. After stopping, the cylinder block temperature decreases unevenly, causing cooling contraction between metal joints. The ticking sound is the friction noise between metals, which is especially noticeable in older vehicles. 2. Solution: If the ticking sound disappears after waiting for a while before shutting off the engine, it indicates that the sound is caused by friction between some metal components in the engine due to cooling contraction. For turbocharged engines, it could also be the sound of the turbo cooling down, which is the noise of metal expanding and contracting with heat.
I just experienced the same issue after repairing my friend's Civic. There was a ticking sound coming from under the car after turning off the engine. This is a normal phenomenon caused by the cooling of metal components. The engine operating temperature can reach over 90 degrees Celsius, and metal parts like the exhaust pipe and catalytic converter expand and contract significantly due to heat. When they cool down and contract, they make this sound. I've observed that it's most noticeable within 10 minutes after turning off the engine, similar to the sound of pouring water on red-hot iron. Older cars usually exhibit this more prominently due to increased gaps from metal aging. Pay attention to the location of the sound—if it's coming from the middle section of the exhaust pipe, it's generally fine. However, if you hear any metal grinding sounds, you should check if the exhaust hangers are worn out. Also, this sound tends to occur more frequently after long drives with the air conditioning on in summer, so don’t worry too much about it.
I've researched this issue for a long time. It's mainly caused by thermal expansion and contraction of the exhaust pipe. When the engine stops, the temperature drops sharply from several hundred degrees Celsius to room temperature, and the connection between the muffler and the exhaust pipe contracts at different rates, producing a crackling sound similar to putting an iron block into ice water. During the last maintenance, I specifically measured that the exhaust pipe shortens by about 2mm during the cooling process. Additionally, turbocharged vehicles are more noticeable, as the cooling of turbo blades after shutdown also produces similar sounds. Usually, the sound disappears within 15 minutes. If it persists for more than half an hour, you should consider loose bolts on the exhaust pipe bracket or internal engine block issues. It's recommended to use a stethoscope to locate the source of the sound.
