What Causes the Abnormal Noise from the Generator Belt?
3 Answers
The causes of abnormal noise from the generator belt are as follows: 1. The belt is too loose or has aged due to excessive mileage: Adjust the belt tension at a repair shop, or replace the belt directly if necessary. 2. Smooth contact surfaces between the belt and pulley: Check for damaged, seized, or loose bearings near the belt. If no issues are found, sand the contact surfaces of the belt and pulley with 100-grit sandpaper and apply a small amount of engine oil. 3. How often should the engine belt be replaced? This depends on the driving conditions. If the vehicle is often driven unloaded, inspect the belt at around 100,000 km and continue using it if no issues are found, replacing it at 130,000-140,000 km. If the vehicle is often driven under load, inspect the belt at 60,000-80,000 km and continue using it if no issues are found, replacing it at 100,000 km.
The alternator belt makes noise, which I've encountered many times. The main reason is aging and wear of the belt, with cracks appearing on the surface or the grooves becoming shallow. You can feel the roughness by opening the engine hood and touching it with your hand. Another common reason is a loose belt or a failing tensioner pulley, causing it to slip and produce a squeaking sound, like nails scratching a blackboard. Also, if the belt is contaminated with oil or dust, the dirt can make it slide unevenly and create noise. If the belt pulley or bearing is damaged, such as a rusted water pump bearing, it can also cause the belt to wobble and make abnormal noises. If not addressed in time, the belt may break, the alternator will stop generating electricity, and the car could stall on the road, which is very dangerous. I recommend cleaning the belt area when washing the car, replacing the belt every 50,000 kilometers, and checking it yourself by pressing the middle of the belt—if it sinks more than 1 cm, it needs tightening.
I often encounter alternator belt noise issues when repairing cars. Personally, I believe the main factor is belt looseness - the squealing sound during slippage is particularly noticeable during cold starts. Wear and aging is another pitfall; after prolonged use, the belt surface hardens and develops cracks, naturally causing friction noise. Additionally, a faulty tensioner prevents proper belt tightness, or bearing failures (such as a seized alternator bearing) can make the belt rattle. I've also noticed that excessive road dust or oil contamination on the belt can cause abnormal noises. This issue shouldn't be ignored - a broken belt stops the alternator, leading to insufficient battery charging and vehicle breakdown, which is especially troublesome when stuck on highways during summer. Simple prevention includes regular visual inspection of belt condition, maintaining engine compartment cleanliness, and avoiding sudden acceleration to reduce load.
