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What Causes a Squeaky Belt on a Car?

Close-up view of an engine belt under the hood

What’s that sound? Your vehicle, which usually purrs like a kitten, has started squeaking like a mouse. If it happens when your car is running, but not moving, it’s most likely an issue with a belt.

What Causes a Squeaky Belt on a Car?Alternator Belt

In newer vehicles, apart from the timing belt or timing chain, there’s now only one belt that powers your car’s equipment, including the alternator, air conditioning, fan, water pump and power-steering pump. Some people call it a drive belt, others an accessory belt, an air-conditioning belt or a serpentine belt because of the way it winds around the wheels that drive all those components.

A squeaky belt could be caused by a few possibilities. It could be the tension of the belt itself, a slightly stretched belt, bad bearings in one of the pulleys or a problem in one of the accessories driven by the belt, such as the alternator, the air conditioner, the water pump or the power-steering pump.

Take a Look and Listen

The alternator and the belt are usually in plain view when you’re looking at the engine, which helps you find, identify and fix the squeaky belt on a car.

With the engine off, open the hood and find the belt. Look for any signs of wear on the belt itself — cracks or parts that are a different shade of black or a different finish (matte vs. shiny).

If it seems normal, leave the hood open, start the engine and look and listen for the squeaks as the car runs. Do they happen when a certain point of the belt reaches a particular point on its path? Watch for any odd movement or vibration of the belt or any of the pulleys.

Next Steps

If nothing is immediately visible, your next move depends on your skill set. If you’re a DIYer and perform other maintenance and repair work on your vehicle, this will probably be something you can handle. But if you’re not, visit a mechanic for a professional diagnosis, repair or replacement.

A final bit of good news — if you’re responding to this squeaky belt early, you’re saving yourself from potential future repairs and malfunctioning parts down the road. When your car talks (or squeaks), be sure to listen.

Check out all the belts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on engine belts, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photos courtesy of Mike Hagerty.

Mike Hagerty View All

Mike Hagerty is an automotive journalist whose work has been featured on radio, TV, in print and online since 1997. He's the Publisher and Editor of, and contributes car reviews to the Los Altos Town Crier and Previous outlets have included KFBK and in Sacramento, California, the ABC television affiliates and Hearst-Argyle and Emmis radio stations in Phoenix, Arizona; AAA magazines for Arizona, Oklahoma, Northwest Ohio, South Dakota and the Mountain West and

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