Auto Repair: 6 Steps to Replace Your Alternator

When it comes to car repair, replacing an alternator is usually one of the most straightforward repairs to make. It requires a minimal number of tools and a minor amount of mechanical ability. Frequently, it is one of the cleaner repairs that you can do to your car because very little oil and grease make it up to where the alternator resides. The tools will usually be a ratchet and socket set and a set of end wrenches. It is recommended that you have both SAE and Metric available.

Start the job by locating the alternator on your vehicle.

The alternator is a cylindrical part that sits high on one side of the engine. One of the fan belts will pass over the pulley that drives the alternator. On newer model cars, the serpentine belt almost always loops around the alternator pulley. Right behind the pulley, will be a set of small fan blades that pull air across the alternator to keep it cool. Two or three wires will be attached to the alternator. It is held in place by two or three bolts.

Remove the fan belt from the alternator pulley.

For cars with a serpentine belt, you will need to put a ratchet on the pulley that provides the tension for the belt. When you apply pressure, the pulley will rotate and release the pressure so that you can remove the belt relatively easily. Try to leave the belt in place as much as possible to facilitate replacing it later.

Disconnect the ground or minus cable from the car battery before removing the alternator wires.

Once the battery cable has been removed, locate the wires that are attached to the alternator. Loosen the bolts that hold them in place and lay the wire aside. If you have problems remembering what wire when where, it can be a good idea to label them or draw a diagram. You may find that one of the wires is difficult to access. If so, do not worry, just wait until you remove the alternator to remove this wire. You only need to be a little careful not to damage it when moving the alternator around before the wire is removed.

When the wires are off of the alternator, it is time to remove it from the car.

Locate the bolts that hold the unit to the mounting bracket. At least one of these bolts will be pretty long and reach possibly the entire length of the alternator. As you remove the bolts, set them in a safe place so they will not be lost. After the bolts are out, you should be able to just lift the alternator from the bracket. You may find the need to tap it with a hammer to get it loose. This does not happen on all cars, but it does happen once in a while. Only tap on the solid areas of the alternator. When you lift it out, remove any remaining wires and note where they were attached.

Take the old alternator to the parts store with you.

There are two reasons to do this. By having the old unit handy, you can compare the new one to make sure that all of the wires can be attached in the same places. Sometimes the plug for the wires can vary from one unit to the next. When this happens, the new alternator will usually come with an adapter to make it work. The second reason to take the old alternator with you is that there is a deposit on the new alternator. By having the old one with you, you will not have to pay this and then get it returned to you later.

Begin installing the new alternator by attaching any wires that could not be removed while the old unit was on the car.

Slide the new alternator into the mounting bracket and insert the bolts into the correct holes. Tighten them into place to secure the new alternator to the mounting bracket. Replace all of the wires to the appropriate connections on the alternator. Slip the fan belt back into place. Reconnect the battery terminal. Start the car to make sure that the new alternator is functioning correctly. Put up the tools, and the job should be complete. On older cars, you will have to tighten the fan belt by prying the alternator up until enough tension is on the belt and tighten the bolt to hold the alternator in that position.