Most modern vehicles use serpentine belts to drive engine accessories such as the power steering pump and water pump. The belt can make noise when it is misaligned, or when its surface becomes hardened. Quieting the serpentine belt should be considered a temporary fix, as the belt will eventually need to be replaced.
Open the hood and locate the serpentine belt. The belt and the accessories it drives will face either the front of the vehicle or the passenger's side of the vehicle, depending on the engine's orientation.
Check the alignment of the serpentine belt. In many cases, the belt will make noise because its edges rub against a pulley. If the belt is not aligned properly, remove it from the pulleys. Line the grooves on the bottom of the belt with the grooves on the pulleys.
Check the condition of the serpentine belt. If it is cracked or frayed at the edges, the belt should be replaced.
Release the tension on the serpentine belt with a belt tensioner pulley tool and remove the serpentine belt. Rotate each pulley, including the belt tensioner pulley. A pulley with worn bearings can be mistaken for a noisy serpentine belt.
Apply a small amount of lubricant on the belt's grooves. This will temporarily quiet the serpentine belt and should not be considered a long-term fix. Replace the serpentine belt if the noise returns.
Never place your hand or any loose clothing in the path of a belt while the engine is running. Doing so can cause serious injury.