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    Identifying and Addressing Causes of Belt Noise

    Avoid Customer Comebacks by Properly Addressing Belt Noise.

    Belt noise can be a real nuisance for you and your customers, prompting them to bring their vehicle to you. As an automotive professional, solving this problem can be accomplished, but there are many misconceptions on the proper way to diagnose and address belt noise.


    The most popular misconception is that you can simply treat belts with a chemical or solvent such as belt dressing, soap, brake fluid, silicone spray, or brake cleaner. Not only are these approaches merely quick-fixes that only mask the symptom more than solve the problem, but these contaminants can actually irreparably damage the belt. So, before you know it, your customer will be back with the same belt noise issues. Often, even replacing the belt is a temporary solution, because belt noise is commonly a signal that there’s a problem somewhere else in the accessory belt drive system.

    Our research has shown two main causes of belt noise:

    1. Loss of tension in the drive: This is typically indicated by a squealing belt at engine startup. The belt squeals because there is improper tension in the belt drive system. This is usually caused by a worn automatic tensioner, but other causes can include a contaminated belt (oil, belt dressing, etc.) or a belt that is too long or worn out. Loss of tension causes the belt to slip, which in turn generates heat that can lead to premature failure of belts, pulleys, and component bearings.


    The solution: The tensioner should always be inspected when there is belt noise. If the tensioner is worn, it should be replaced. Moreover, make sure the correct belt is installed on the vehicle, and that it is not excessively worn by checking it with Gates belt wear gauge tool . Be sure to also inspect the accessory belt drive system for fluid contamination. If a leak is found, repair it, and then inspect the system again to confirm the issue has been addressed. Also, if the belt was contaminated by the leak, it should be replaced as well.


    2. Misalignment: A chirping belt typically indicates an alignment problem between one or more components in the drive . Components that are out of alignment by as little as one degree can create belt chirp as the belt ribs slide down one side of the pulley grooves.


    The solution: If you hear the belt chirp, address the alignment issues. The easiest way to correctly diagnose misalignment is to use a laser alignment tool.


    By solving the root cause of belt noise, you can address belt noise issues the first time and avoid customer comebacks, and greatly prolong existing and future belt lifespans. We explain more about heavy duty belt noise and how to address it in this video: