What Causes the Noise Under the Chassis After the Car is Turned Off?
2 Answers
This is primarily due to the sound caused by the cooling of the exhaust pipe's three-way catalytic converter after the engine is turned off, which is a normal phenomenon of thermal expansion and contraction. Below is a related introduction about the chassis: Introduction: The chassis refers to the combination of the transmission system, running system, steering system, and braking system in a car. It supports and installs the car engine and its various components and assemblies, forming the overall shape of the car, bearing the engine's power, and ensuring normal operation. Function: The role of the chassis is to support and install the car engine and its various components and assemblies, forming the overall shape of the car, and receiving the engine's power to make the car move and ensure normal operation. At the same time, a good chassis can ensure the driver's safety.
Having worked in the automotive repair industry for so long, I often encounter car owners asking why there are strange noises from the chassis after the engine is turned off, especially after parking in high summer temperatures. Most of the time, it's due to thermal expansion and contraction—for example, the clicking sound from metal contraction as the exhaust system cools down, or slight vibrations caused by the brake discs cooling. Other chassis components, such as suspension links or drive shafts, may also make noises due to stress changes if the car isn't parked level. These are mostly normal physical phenomena, so there's no need to worry too much. However, if the sound is unusually sharp, lasts for a long time, or is accompanied by a burning smell, then you should be cautious, as there might be loose components, oil leaks, or exhaust leaks. It's advisable to regularly check the chassis bolts during routine maintenance to prevent potential issues and avoid the hassle of repeatedly inspecting the car late at night after turning off the engine.
