Can You Spray WD-40 On A Squeaky Engine Belt?
A sound familiar to most drivers is the high-pitched squeal that comes from the belt-driven accessories mounted on the front of a majority of engines. This can happen when the belt is too loose or too tight, when the pulleys for the various accessories and tensioners are misaligned, or the bearings or clutches in those components have reached the end of their useful life.
Although people have utilized WD-40 for some wild off-label purposes, among its main stated uses are to quiet sticky items like door hinges and prevent your car's locks from freezing in cold, wet weather. WD-40 has lots of other automotive uses: it can help free up rusty fasteners, remove decal residue from your windshield, and dry out distributor caps and spark plug boots. WD-40's noise-eliminating ability might make it tempting to use it on car belts that have become an embarrassment at stop lights or in parking lots, but is it safe to spray WD-40 on a noisy car belt?
You shouldn't use regular WD-40 on car engine belts
The short answer is no, regular WD-40 should not be used on your car's belts. These belts require a precise amount of tension to work properly, and WD-40 is a lubricant and could lead to belt slippage. It also contains compounds that can damage the rubber in your belts, shortening their lives. WD-40 does make a special product for quieting belts that are making noise because they are drying out or slipping.
WD-40 Specialist Belt Dressing is available from Auto Pro in the United States or Repco in Australia and is perfectly safe to use on squeaky accessory belts. To use it, start your engine and raise the hood. Spray a light coat of the belt dressing on the inside of the belt near the smallest pulley or the one closest to the top of the engine. Allow the rotation of the engine and accessories to circulate it properly. The belt dressing will soak into the belt's fibers, softening it and reducing or eliminating the noise. If your belts still squeal loudly after use, check for proper tension and pulley alignment.