Q&A for How to Put on an Alternator Belt

Take photos of the belt set-up before making any changes. This way, you know exactly how the belt should be routed around the various pulleys. Make sure that your photos make sense to you and are clear.

Find the tensioner bolted to the block or vehicle—it will have a square hole that accepts a 3/8 or 1/2 inch ratchet end. Attach the ratchet and rotate it to reduce the tension on the belt.

Loosen the bolt on the sliding mount of your alternator. If the alternator will not slide, you may need to loosen the other bolts for the alternator, but do not remove them. The sliding mount has a bolt through a slot on one of the mounting brackets that the bolt slides through.

Visually inspect the belt and compare the install to any pictures that you took of your old setup. Then, start the vehicle and listen for any squeals or other unusual sounds. Also, keep an eye on the rotation of the pulleys, and check for any lights on the dash.

No. The serpentine belt is the power that turns other important components of your vehicle. The engine turns the belt through a pulley from a water pump, and that power is connected through the belt to other items, such as AC compressors and alternators and power steering units. When the belt turns the pulley associated to a component, it powers that unit to function. Not having your belt on can cause a variety of mechanical problems very quickly.

Check for damage to a pulley or something in a pulley rib (stone, old piece of belt etc.), make sure that all pulleys turn smoothly and no free play due to worn bearings, and look for a plastic guard that may be loose coming in contact with the belt occasionally.

If the belt has not come off entirely but has stopped moving, chances are one of the other components that moves the belt has stopped working. When a vehicle is running, the belt is driven by the rotation of an engine component, such as the water pump. The belt then drives other components by turning the pulley in the belt circuit. Troubleshoot the problem by identifying the elements that turn the belt and making sure they are in working order.