How to Inspect and Replace an Alternator Drive Belt for the Average Joe

Mechanics know that your drive belt, when loosened, can cause problems in the charge system, and then your problem may not be your alternator or even your battery. Along with heating up the rotor's shaft, the slipping belt can cause your drive end bearing to go out. The regulator attached to your alternator builds an electrical field in the rotor on your alternator, and in turn the load is then put on the drive belt. If your drive belt becomes loose, it can slip and then won't be able to handle the electrical load the regulator puts on it.

To begin, inspect the entire belt by looking for shiny spots or what is called glazing. Also look for rot or cracking, as this is a sign of abnormal wear as well. Now try to pull the alternator's fan with your car turned off, and if it slips, the belt is way too loose and has to be fixed.

To replace your belt, you have to locate the idler pulley. This is always on the left side of the vehicle, in front of the radiator fan and directly beneath the pulley for your alternator. There will be a small sticker under the hood on the body. This has the location of the idler arm and the adjustment hole that you will need to find. The tool most common for this job is a ½ inch drive, and it is inserted into the hole and pulled towards the left side of the vehicle to loosen the tension. While you are holding the tension off of the pulleys, you will want to pry the belt towards your body with your fingers, and pull up and away from the pulley to release it.

Make sure you match up the size from your old belt to the new one. Sometimes we are given the wrong one for the right car, because there are a few belts generally that will fit a few different vehicles. Look at the sticker you seen before that has the pulleys on it, and find what the belt routing is inside your engine compartment.

Manufacturers sometimes suggest that you use a sequence for feeding your new belt over the pulleys, and if this is included on the sticker, by all means use it.

The very last step to installing your new belt is to again use the ½ inch drive in the tensioner hole. Keep the tension off of the pulleys while you use your fingers to pry the belt back up over the top of the alternator pulley. Remember this is always the top left pulley, and is the easiest to get to without dismantling your fan shroud and other components.

Now that you are done, go fire up the engine and see how great a job you just did. Not only did you save money, but you did it yourself and congratulations for the confidence