What Causes the Abnormal Noise After Starting the Car?

[CorbinMarie]

Reasons for abnormal noise when the car just starts are as follows: 1. The car has not been used for a long time: The engine oil returns to the oil pan, meaning the top of the engine, specifically the valve chamber, lacks oil. Since the valves are missing the sealing and lubrication provided by the oil, you may hear abnormal noises from the bottom of the car when it first starts. This situation is normal. 2. Issues with the engine belt: Abnormal noise from the engine belt is due to the belt being dirty. Cleaning it with water or applying some lubricant can eliminate the noise. However, whether this solution is suitable for all car models requires further analysis.

[Trudy]

I'm quite concerned about the abnormal noises after starting the car. Common causes may include belt system issues, such as aging or loose engine belts that produce squealing sounds, or worn-out bearings in the alternator or water pump that create rattling noises, which are quite unpleasant. Another possibility is loose exhaust pipe bolts, which can cause metallic knocking sounds during cold starts, and these are particularly noticeable. When my own car had this issue before, I first identified the source of the noise—for example, if it was a belt squeal, I checked the tension and tightened it if it was too loose; if the bearings were damaged, they had to be replaced. Ignoring these abnormal noises can range from affecting driving comfort to causing mechanical failure and leaving you stranded on the road. So, I recommend performing a simple self-check first and then promptly taking the car to a professional repair shop for further inspection.

[McNaomi]

After years of driving, I've concluded that startup noises mostly come from belts or bearings. A loose belt will squeal, while a faulty water pump bearing makes a thumping sound. Loose exhaust pipes causing rattling noises are also common. From experience, you can guess the issue by the sound type: high-pitched screams indicate belt problems, while low rumbling points to exhaust pipe issues. I usually pop the hood, carefully listen for the source location, and check the belt for cracks or looseness. Tightening a belt myself is manageable, but replacing bearings is better left to a repair shop for safety. Preventively, replacing the belt every two years effectively avoids noise issues, saving time and hassle.

[SanJosephine]

The most common cause of strange noises after starting is a loose belt or a faulty bearing, which produces unusual sounds. For a simple self-check: first, observe if the belt has many cracks or is too loose; tightening it might solve the issue. Loose exhaust pipe bolts can also cause noise, and tightening them manually may help. Different noise sources require different handling methods, but the general principle is not to delay—address it immediately with minor repairs or take it to a professional shop. Ignoring strange noises can turn minor issues into major problems, such as a broken belt damaging other components, increasing repair costs.