GAC gs3 - Why Is Crackling Sound Heard from the Chassis Sometimes after Cold Start or Shutdown of the Engine; Why Is Cooing Noise Heard When the Brake Pedal Is Released to Start the Vehicle with at

62
Q&A
Why is crackling sound heard from the chassis
sometimes after cold start or shutdown of the engine?
During cold start, the exhaust pipe and other components will expand
rapidly due to heating, producing crackling sound occasionally; likewise,
after the engine is shut down, the exhaust system will contract with
temperature drop, and similar sound will arise occasionally at this moment.
Please don’t worry because it is a normal phenomenon of expansion
caused by heat and contraction by cold, which won't cause any damage to
the vehicle.
The temperature of the gas exhausted from the engine is high. During
cold start, the temperature of the exhaust system will rise rapidly when
the high﹣temperature gas passes through the exhaust system. Owing to
the principle of expansion and contraction, the exhaust pipe will expand
slightly, producing light sound in the vicinity of the exhaust pipe; likewise,
after the engine is shut down, the exhaust pipe will contract slightly due to
the principle of expansion and contraction, making light sound in the vicinity
of the exhaust pipe.
Please feel relieved to use the vehicle because the phenomena
mentioned above are normal.
Why is “cooing” noise heard when the brake pedal is
released to start the vehicle with AT?
When the driver is going to brake or release the brake pedal to start the
vehicle with AT, the engine is still transmitting power for the vehicle, and
meanwhile the braking force still exists between the brake disc and the
brake lining, generating friction sound between them. And this sound
becomes cooing after being amplied by the compartment. Most vehicles
with AT have such sound, which is normal.
Please feel relieved to use the vehicle because the phenomena
mentioned above are normal.