What Causes the Abnormal Noise from the Chassis After a New Car Shuts Off?
3 Answers
Here are the specific reasons for the abnormal noise from the chassis after a new car shuts off: 1. Disc Brake Malfunction: When the vehicle is driven at low speed on a flat road, irregular intermittent noises occur at the wheel hub area. The noise slightly intensifies as the speed increases but remains unchanged during uphill, downhill, or turning. The noise worsens when driving on uneven roads and reduces or disappears when the brake pedal is pressed. During a stationary inspection, rotating the wheel back and forth can reproduce the noise. This is caused by damage, deformation, or detachment of the brake shoe support plate, damping spring plate, or guide plate of the disc brake, which increases the gap between the brake shoe and the caliper support frame, leading to collisions and noise. Visit a repair station to fix deformed parts or replace detached ones. 2. Front Suspension Ball Joint Malfunction: When driving at low gear on bumpy roads, continuous noise is heard from the front axle area. The worse the road condition, the louder the noise, which intensifies with speed. After stopping, forcefully shaking the front of the vehicle will produce noise. On flat roads, irregular intermittent noises resembling the sound of metal breaking may occur from the front axle. This is due to excessive clearance between the ball joint and its socket, causing severe looseness. Since the ball joint socket is a sealed structure and cannot be disassembled, replacement at a repair station is the only solution. 3. Front Wheel Shock Absorber Malfunction: On flat roads, slight noise from the front of the vehicle can be heard, intensifying during sharp turns. During a stationary inspection, pressing down on the front of the vehicle to make it rebound up and down will produce noise, which becomes louder with more force. The vehicle also feels less elastic and not as smooth. This usually happens when the vehicle is frequently driven on rough roads with poor maintenance, leading to shock absorber oil leakage and damage. Depending on the severity of the damage, repair or replacement at a repair station is necessary.
I just bought this new car less than three months ago, and there's always a clicking sound from the chassis after turning off the engine. Feeling a bit worried, I asked a friend who's familiar with auto repair. He said this is due to the sound of parts contracting as the engine cools down, especially the exhaust pipe and catalytic converter, which deform as they cool after high-temperature operation—a common cause. New cars have tightly fitted metal components, making thermal expansion and contraction more noticeable. If it's just a few brief clicks after parking and doesn't happen every time, it's generally normal. However, if the sound is loud and accompanied by vibrations, it might be an assembly issue or loose fastening screws, requiring a check at the 4S store. Usually, it's good practice not to park immediately after aggressive driving; letting the car cool down slowly may reduce the noise, which is quite useful advice for maintaining my new car.
I've repaired many cars before, and the common cause of chassis noises after a new car is turned off is thermal effects. The exhaust pipe emits slight clicking sounds as it cools and contracts after high temperatures. The catalytic converter, made of special materials, is prone to deformation, which can cause noises. Sometimes, the welds or joints of chassis components are also involved. Don't panic when you hear these noises—most are part of the normal process. However, if they occur frequently or sound sharp in a new car, it might indicate improper installation or loose parts like the fuel pump. It's advisable to have a professional diagnose the issue to avoid major repairs later. Maintaining a smooth transition in engine temperature while driving can help alleviate this problem.
