What are the causes of abnormal noise during car idling?
2 Answers
Reasons for abnormal noise during car idling: 1. Abnormal noise caused by excessive clearance, which refers to the abnormal noise caused by the wear of a certain part of the engine that makes the clearance too large; 2. Abnormal noise due to engine misfire, mainly refers to one or more cylinders of the engine not working properly; 3. Abnormal noise of engine knocking refers to the sound of knocking when the car starts. Piston knocking noise refers to the abnormal noise caused by the piston swinging or moving up and down in the cylinder, and its head or skirt colliding with the cylinder wall or cylinder head. Idling is a working condition of the car, which means that the engine is running in neutral gear, and the speed of the engine during idling is called the idling speed.
With over a decade of experience in car repairs, I've seen plenty of cases of abnormal noises during idle. The most common issue is belt-related—like a worn-out or loose fan belt that squeaks when rubbing, or a damaged auxiliary belt pulley bearing that produces a whining sound. Engine internals often cause trouble too; worn valve lifters or piston rings can lead to unstable idling and a tapping noise. Poorly secured water pumps or air conditioning compressors may also result in a humming sound. I recommend car owners check belt tension and lubricant levels monthly, replacing old parts promptly to prevent noise from worsening into bigger failures. If the noise resembles metal grinding, get it to a repair shop immediately—don't delay. Engine health is critical to driving safety, and proper maintenance saves major headaches.
