Why is there abnormal noise when starting the car?

[StCaroline]

Reasons and solutions for abnormal noise when starting the car are as follows: 1. The engine temperature is too low. During cold starts, the engine temperature is too low for normal operation. Solution: This is a normal phenomenon; simply wait for the engine temperature to rise to normal levels. 2. Thermal expansion of the car's three-way catalytic converter. Abnormal noise that occurs when the car is first started but disappears after a while is caused by the thermal expansion of the three-way catalytic converter. Solution: This is a normal phenomenon. 3. Transmission failure. A malfunction in the transmission can cause internal gears to rub, resulting in abnormal noise. Solution: Professional inspection and repair at a repair shop or 4S store are required. 4. Wear of the engine belt or chain. Wear of the engine belt or chain can also cause friction or abnormal noise due to idling when starting the vehicle. Solution: Directly replace the engine belt or chain.

[StElisa]

I've encountered starting noise issues while driving, most commonly caused by aging starter motors. When the starter motor gears are severely worn during ignition, they produce a clicking sound, similar to teeth slipping. Alternatively, it could be due to loose drive belts, especially the alternator belt or A/C belt, which emit a squealing noise when starting if they've become brittle with age. Additionally, during cold starts, if the engine oil hasn't fully circulated, increased friction between components like pistons can cause minor noises. If accompanied by shaking, it might indicate a loose exhaust system or broken mounting brackets. I recommend starting with a belt inspection—check for cracks by pinching them and adjust or replace if loose. If the noise persists, seek professional diagnosis to avoid potential stalling issues on the road.

[SanFernando]

Last time, the strange noise when starting my car gave me a fright. My neighbor told me it might be due to the lubricant thickening in cold weather, causing brief noises, which is normal, but if the sound gets louder, it needs attention. Sometimes, it's because the battery terminals are loose, causing unstable voltage that makes the starter buzz, or the air conditioning compressor belt is worn and squeaks. The check is simple: visually inspect the belt for cracks before starting, and listen to where the noise is coming from; noises from under the front hood are mostly mechanical issues, while louder noises inside the cabin might indicate an exhaust pipe leak. I learned a little trick to warm up the car for a few minutes before driving to reduce strange noises; of course, if the noise is loud and lasts a long time, it's best to get it repaired promptly for peace of mind.

[TannerFitz]

Don't underestimate abnormal noises during startup, as they may indicate hidden safety hazards. For example, a harsh metallic sound could mean the belt bearing has failed, and continuing to drive may lead to belt breakage and engine shutdown; a rattling noise suggests a faulty starter motor, risking getting stranded on the road. While noise during cold starts is common, increasing frequency can be dangerous. I've personally encountered similar situations—I quickly pulled over to check the belt and electrical system, preventing worse outcomes. If you hear unusual sounds, it's advisable to stop immediately and contact a mechanic for peace of mind while driving.