Fontanot Arke Stairs

What Could be Causing the Loud Screech Under the Hood of My Car

DIY Questions and Answer June 13, 2012 Sonia



Q. Last week a loud screech started coming from beneath the hood of my car. Any idea what causes this?

A. It’s possible that a Capuchin monkey has made a home in your engine bay. Otherwise, the screech is probably coming from a worn-out serpentine belt. Eventually the rubber of the belt wears out of weakens from exposure to oil and heat. A short-term solution for silencing the squeal is to spray a product called belt dressing onto the belt to lubricate it. However, this will only work temporarily and the noise will return. The best approach is a full replacement. Most serpentine belts have a spring-loaded tensioner, which you can loosen with a ratchet to unwrap the belt from the pulleys. (This will also be a good time to replace the belt tensioner.) Check all the pulleys for misalignment if the belt shows signs of uneven wear. Replace the belt and tighten the tensioner bolt according the torque recommendations in your vehicle owner’s manual.