What causes the clunking sound when starting the car?

[DaniellaMarie]

The reasons for a clunking sound when the car starts are as follows: 1. Faulty lower control arm or worn inner CV joint, manifested as abnormal noises when turning or starting, and clunking when suddenly accelerating after releasing the throttle. In severe cases, it may lead to axle breakage. 2. Possible causes include clutch failure, transmission issues, lower control arm problems, or inner CV joint wear. It is recommended to visit a local 4S dealership for inspection and repair. Additional information: 1. Various vibrations from different mechanisms during car operation can produce sounds of different natures. However, not all sounds indicate a malfunction. To avoid unnecessary disassembly, it is essential to distinguish between normal and abnormal sounds. Normal operational sounds include engine surface noise, gear impact noise during gear shifts, intake and exhaust sounds from gas-operated sources, and gear meshing noise. 2. Abnormal sounds (or noises) can be categorized based on their impact on vehicle performance: minor noises, general noises, and severe noises. Minor noises, such as sparking from high-voltage electrical leakage or slight looseness in rolling bearings, are generally low in volume and do not significantly worsen over time. These issues typically do not require immediate repair for the car to continue normal operation.

[VincentLynn]

When the car starts and suddenly makes a clunking sound, I've encountered this situation several times. At first, I thought it was nothing, but later I realized it might be an issue with the starter motor or the relay repeatedly clicking. The main causes include insufficient battery power leading to poor contact, or the motor gear not fully engaging with the flywheel ring gear, resulting in that metallic collision sound. Sometimes it's also because the car is old, and the engine mounts or belts have become loose. I suggest first checking the battery voltage with a multimeter to see if it's below 12 volts, and then observing whether the sound persists during startup. If not addressed in time, it might damage components or make starting even harder. Remember, this is more common in winter, as low temperatures cause materials to contract, increasing the risk of unusual noises. It's always a good idea to have it checked by a professional repair shop.

[SanLeila]

When starting the car, a 'clunk' sound is most commonly caused by issues with the starter or battery. For example, the relay may repeatedly make a clicking sound when the current is unstable, which sounds like a 'clunk'—this is often due to an aging battery. Poor gear engagement can also cause a collision sound, especially if the car has high mileage and the transmission components are worn. I feel this is not a minor issue; it's essential to ensure the system is functioning properly before driving, otherwise you might break down on the road. A simple step is to check the voltage indicator on the dashboard or try starting the car a few times over a short distance. Regular maintenance, such as inspecting the battery and connections every six months, can effectively prevent such problems. Safety first—don't ignore small issues.

[Hope]

A clunking sound when starting the car is mostly due to a starting system malfunction. Common causes include poor engagement of the starter gear or the relay repeatedly activating. Inspection method: Open the hood and listen for the source of the sound. If the battery is low, try jump-starting. If the sound occurs only once and the car starts normally, it might be due to metal expansion from a cold engine, which is temporarily not a concern. However, if it happens frequently, it's best to take it to a repair shop. Simply put, this is related to aging, and timely action can prevent greater damage.