Replacing an Alternator

Is Your Alternator Out?

Perhaps you've noticed your headlights dimming while driving, or maybe you have an ongoing problem with a perfectly good battery that keeps running out of power, even after you've had it recharged a time or two. Or your battery light flickers on at low RPMs, or is on all of the time. These are all signs that your alternator is busted.

Beginners Beware

Changing an alternator at home should only be undertaken by someone with mechanical skills. If you've never worked on car maintenance before, this might not be the best "first job" for you. Read all the steps and decide whether you are comfortable with this repair before you undertake it.

What You'll Need to Get Started

  • The correct service manual for your vehicle's make and model.
  • Tools and equipment as outlined in your vehicle's service manual.
  • Proper replacement alternator (see below).
  • New alternator belt.
  • Any other hoses or belts that will require removal in the process of replacing the alternator.
  • A memory saver. This device plugs into your cigarette lighter and saves all your computerized PINs and codes, (including your engine settings as well as your stereo presets) so you don't have to reenter any information.

The alternator is not a "stock" type of part on a vehicle. The location, parts, tools, and skills needed to change it differ from vehicle to vehicle. Be sure you're using the right tools for your case, to prevent injury to yourself or to your car.

Although it seems unnecessary to get new hoses and belts just because you've removed them to get to the alternator, you should. When you take these off, the hose and belt are likely to become stretched or damaged in ways you can't see. It's a safety measure, and doing so will cut down on damage or premature belt and hose wear.

Removing the Old Alternator

If you have another way to get to the auto parts store, remove the old alternator from your vehicle first. Follow these steps to accomplish this removal:

  1. Plug in your memory saver, if you have one.
  2. Remove the vehicle's negative battery cable.
  3. Remove the serpentine belt, or alternator belt. This is many times the most difficult part of the task.
  4. Remove any necessary parts to reach the alternator.
  5. Discard all belts or hoses removed in this process.
  6. Disconnect all of the electrical connections (wires) from the alternator.
  7. Disconnect and discard the alternator belt.
  8. Remove any mounting bolts that hold the alternator in place.
  9. Remove the alternator from the engine compartment.

What About the New Alternator?

Now, take the old alternator to the auto parts shop and purchase the new alternator. It will be less expensive if you take the worn alternator and trade it in on the new one. If you do not provide the old part, most auto parts stores will add an additional fee to the listed price of a part such as an alternator.

This is legal, and is known as a "core charge" in the industry. However, the core charge is refundable with your old alternator and receipt.

Installing the New Alternator

  1. Set the alternator back in place in the engine compartment.
  2. Reattach any mounting bolts to hold the alternator in place.
  3. Reattach all electrical wires to their proper connections.
  4. Place the new alternator belt over the pulleys or or replace the serpentine belt.
  5. Replace all hoses and belts that required removal.
  6. Replace and reattach all engine components that were removed.
  7. Reattach the negative battery cable.
  8. Remove the memory saver, if used.

A Few Helpful Tips

  • Never over-tighten the alternator belt, as this will cause premature wear on the bearings.
  • To reduce back strain, raise the front of the vehicle with jack stands placed in the correct spots for your vehicle. The wheels need not be elevated off the floor, but be sure your stands are in the right place for your particular vehicle to avoid damage.
  • Reconditioned parts are great, and they're major money-savers for do-it-yourselfers. However, if you do plan to use a reconditioned part, do some research beforehand either on the Internet or by asking other home mechanics. While they are usually a great bargain, it's best to know which line has the best reputation; reconditioned auto parts vary greatly in quality.
  • Be sure to properly dispose of any oily rags.
  • Make sure you know the proper disposal procedure for the hoses, belts, and any other parts you have replaced. These regulations are different depending on where you live. If you are unsure, ask the auto parts store for this information.

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