Why does the car make a squeaking sound when starting?
2 Answers
Car starting with a squeaking sound is usually caused by a loose timing belt or an abnormal timing belt. The timing belt is an important component of the engine system. It connects to the crankshaft and works with a certain transmission ratio to ensure the timing of engine intake and exhaust, thus maintaining normal engine operation. The reason why cars use belts for transmission instead of gears is that belts produce less noise and provide precise transmission. Under high-temperature operating conditions of the engine, incorrect matching and installation of the timing belt tensioner can affect the service life of the timing belt. During the car's starting process, whether it's a cold start or a normal temperature start, if a squeaking sound occurs, the timing belt should be replaced promptly.
Every time I start the car and hear that squeaking sound, I get really nervous. After doing some research, I found out this issue is actually quite common. The most likely cause is aging belts, especially the alternator belt and A/C compressor belt. After several years of use, they can harden and crack, causing insufficient friction and squeaking during startup. Another common issue is a faulty starter motor, where the internal gears or solenoid switch wear out, producing a sharp grinding noise when starting. If the noise is particularly loud when the engine is cold, it might be due to a loose drive pulley bearing. I once paid close attention and noticed that if the sound comes from under the steering wheel, it’s usually a belt problem, whereas if it comes from the back of the engine, it’s likely the starter motor. I’d recommend getting it checked at a repair shop ASAP—severely slipping belts can affect the charging system, and a dead battery would be really inconvenient.
