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My serpentine belt is making a noise. How do I determine what’s causing it?

May 13, 2021

There are two very distinct noises caused by different issues – one is a chirp, the other is a squeal. Your best course of action is to conduct a water test to see which one you are dealing with. With the vehicle idling, spray water on the belt’s rib surface. Then listen closely. If you hear a sharp, high-pitched, repetitive noise of short duration that is worse at low engine speeds (idle), you are dealing with a chirp alignment issue. If you hear a high-pitched noise that typically lasts several seconds and increases in volume as engine speed increases, you are dealing with a squeal, which is typically caused by a slip between the belt and pulleys. The noise will go away with the water spray if it’s a squeal, it will not if it’s a chirp. Check out our article on diagnosing belt noise for more.