What are the causes of abnormal noise when starting a car?
2 Answers
Reasons for abnormal noise when starting a car: 1. Engine temperature is too low: During cold starts, the engine temperature is too low to function properly; 2. Thermal expansion of the car's three-way catalytic converter: If there is abnormal noise when the car is first started, but it disappears after a while, this is caused by thermal expansion of the three-way catalytic converter and is a normal phenomenon; 3. Transmission failure: One of the reasons for abnormal noise when starting a car is a transmission failure, which causes internal gears to rub and produce noise; 4. Wear of the engine belt or chain: If the engine belt or chain is worn, it can also cause friction or abnormal noise due to idling when starting the vehicle.
It's quite common to encounter abnormal noises during car startup, usually caused by aging or worn-out components. When the bearings inside the starter motor wear out, they produce a metal grinding sound, especially noticeable during cold starts before the oil has properly lubricated the parts. If the belts are too loose or have hardened, they may squeak, which is mainly an issue with the drive belt or AC belt. Another cause could be poor contact in the starter relay, resulting in a ticking sound. From my experience, most abnormal noises are minor warnings. For instance, my old car used to make noises because the belt wasn't replaced on time, and a simple replacement fixed the issue. However, prolonged neglect can lead to the starter motor seizing up or the belt snapping, potentially affecting other systems like the alternator. I recommend car owners first identify the noise location—front-end sounds may indicate belt issues, while a buzzing sound from under the car could point to an exhaust pipe crack—and then visit a professional repair shop as soon as possible to prevent minor issues from escalating. Regular checks on belt tension and replacement schedules can help reduce such noises.
