What Causes Belt Noise Video - Pep Boys

Pep Boys warns... Don't always blame the belt. Let's start with an assumption that happens to be fact: The noise coming from an accessory drive is not usually the fault of the belt. Noise generated by a belt can be of several types and can be caused by a variety of problems. Sometimes installing a new belt may seem like a fix, but if the drive is not inspected and problems like misalignment and tension are not remedied, the noise will return along with a dissatisfied customer. This video addresses the two main types of belt noise; Chirp and Squeal. They are different noises and they have different causes. Chirp is a series of sharp, intermittent noises. As belt speed increases, pitch and volume stay constant. Chirp is often a result of misalignment between consecutive pulleys on a drive. It can also be caused by improper installation, extremely worn ribs, worn pulley bearings and fluid contamination. Chirp occurs more frequently in poly rib drives than in V-belt drives. The most common cause of chirp can be either axial or angular. Axial misalignment is the most common, but both should be checked.
Squeal is a high pitched noise that last several seconds, does not change in pitch as the speed varies but may change in volume with increased speed. Squeal may be continuous or intermittent, change with acceleration or added accessory load like the AC compressor. A new belt can seem to resolve the noise problem. Most brands of belts contain fiber especially Dayco's W profile belt. Once the fiber has worn off and the ribs become more seated the belt performs more aggressively. If the misalignment has not been identified and remedied the noise problem has not been fixed. The direct cause of squeal is slip between the belt and pulleys. Usually the slip results from low belt tension due either to low installation tension, tension decay, stretch or sidewall wear. Slip may also occur due to high loads resulting from bearing drag or an accessory ready to fail. Under-designed drive slips are due to high accessory load or insufficient wrap on the driven pulley. Belt dressing or contamination by oil or anti-freeze may also cause slip.
Dayco belts are available at your neighborhood Pep Boys Auto Store or find out more online at www.PepBoys.com.
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