How to replace your alternator

car-alternator- courtesy of virginmedia.com

The alternator distributes power from the engine to the battery, and is one of the most important components of a car. Replacing an alternator can often be expensive at a shop, but if you have two to three hours to spare, and a bit of experience working with cars, you can easily replace it on your own. Since you must remove the V-belt in the process, this project is a good time to replace that, as well.

Aside from new parts, you'll want to have a socket wrench set, combination wrenches, vise grips, and a screwdriver. When buying a new alternator and V-belt, you may want to bring your old ones to the parts store (if possible) just to make sure that your replacements look exactly the same; in particular, V-belt length can vary not only with the make and model of your car, but also the accessories you have on it.

1. Park in a garage and make sure your car has been off long enough to be cool before beginning.
2. Disconnect the negative terminal of your battery. This will keep any wires coming from the alternator from shorting out if they touch metal, so you're protecting yourself and your car by doing this.
3. Loosen, but don't remove, the two mounting bolts that hold the alternator in place. This may require a couple of wrenches if the bolts have nuts on the back.
4. Rotate the alternator in the direction that the V-belt moves, just enough to loosen the belt so you can remove it from the alternator. Take the belt off of the rest of its pulleys as well.
5. Now you can remove the wires from the back of the alternator. Use some masking tape and a pen to note where each wire goes; you may even want to take a picture or draw a diagram to help you replace the wires later.
6. Remove the mounting bolts from the alternator, and remove the old alternator.
7. Put the new alternator in, and then slide the mounting bolts in, through the engine brackets, but don't tighten them yet. The alternator should stay on its own, without swinging down.
8. Put the new V-belt on, placing it around the engine pulleys first, and the alternator pulley last.
9. You'll need to make sure the V-belt is at the proper tension before you can tighten the alternator's mounting bolts. Rotate the alternator so that the V-belt doesn't have any visible slack. Then use your vise grips to tighten around the slotted bracket of the alternator; basically the grips help to hold the alternator against the V-belt and keep it taut.
10. Pull the alternator about ½ inch to tighten the belt, and reposition your vise grips accordingly. Now finish tightening the mounting bolts for the alternator, and take off the grips.
11. Use your diagram or photo in order to reconnect the wires to the alternator.
12. Reconnect the negative battery terminal.
13. Start the car. If you hear a squeal, the belt is too loose, and you may have to tighten the alternator's position again with the vise grips.

—Seth Berger

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