How to Identify Abnormal Noises from Engine Belts?
3 Answers
Methods for identifying abnormal noises from engine belts: You can determine which belt is causing the issue by listening to the sounds. If the noise occurs when the air conditioning is turned on, it might be the air conditioning compressor belt. If the noise appears during a cold start, it could be the engine belt. You can troubleshoot step by step. More relevant information is as follows: 1. Causes of abnormal noises: If there are unusual sounds in the engine compartment, it is usually due to loose or poor-quality belts. Therefore, the first step is to inspect the engine belt. If there are multiple belts in the car and you can't pinpoint which one is the problem, start the car and pour some water on the belts. If the noise disappears, it indicates that the belt is the issue, and you can check whether it's loose or of poor quality. 2. Pouring water on the belt: Pouring water on an engine belt that is making noise increases its stickiness, effectively enhancing the belt's adhesion. However, once the water dries, the belt will return to its original state. This is the principle behind pouring water on the belt.
With years of driving experience, I diagnose engine belt noise step by step. After starting the engine, I carefully listen for the source—usually a squeaking or screeching from the front compartment, often indicating a loose or worn belt. After parking, I pop the hood and manually press the belt's midsection to test tension; excessive slack means adjustment is needed. I then inspect the belt surface for cracks or fissures, using my phone's flashlight for better visibility. If the noise worsens in wet weather, it might be belt slippage from moisture. I also note whether the noise intensifies with RPM: high-speed squealing often points to insufficient tension, while sharp screeches may suggest pulley dust buildup. Finally, a quick water spray test helps—if the noise fades, the belt is aging; if not, a professional pulley system check is needed. This straightforward method, which I often perform in my home garage, helps prevent bigger issues.
Identifying belt noise, my experience is to distinguish the sound types. A squeaking sound usually indicates a loose or aging belt, especially noticeable during cold starts, and can be tested by hand pressure; a high-pitched whining sound suggests belt slippage, often occurring on rainy days or in high humidity; a humming or knocking sound may indicate a damaged pulley bearing or foreign object stuck. I combine speed changes to diagnose—if the noise is slight at idle but worsens with acceleration, it's a tension issue. Regular belt inspection is crucial—look for cracks or shiny areas indicating excessive wear. I also recommend using a simple stethoscope to listen closely near the pulleys for more accurate diagnosis, avoiding misjudgment. Remember not to ignore abnormal noises—address them early, as a broken belt could lead to major engine repairs.
