How To Replace Alternator

Learning how to replace an alternator for your vehicle is one of the most useful things you can learn how to do when it come to the upkeep of your car. The whole scenario around having to replace an alternator just plain sucks. Most of the time, before you realize the alternator needs to be replaced, you make the assumption that the battery of your car just died. So, if you're a do-it-yourself kind of guy you just replace the battery and go about your business.

Unless you have the diagnostic tools to test your battery and alternator, you don't realize you need to replace the alternator until your car goes lifeless again. At this point you have two options. You can either pay someone to put a new alternator in your car, or figure out how to do it yourself. Hopefully your engine isn't too complex or you'll have to take your car in for the work. If you can get to the alternator yourself, then you're better off learning how to replace it on your own. Replacing an alternator isn't easy, but it's better that you know how to do it yourself than have to pay some crazy labor fee.

What you need.

  • Socket wrenches
  • Flat head screw driver
  • Either a buddy to help or vice grips
  1. First and Foremost. Never do work under the hood of your car with the battery attached. You run the risk of hurting or even killing yourself if something goes wrong. Some people just disconnect the negative side of the battery. To be safe, disconnect both. 
  2. Removing the bad alternator. Locate the alternator under the hood. You'll know what it is because it'll have a thick rubber band wrapped around one end that stretches and twists to another part of the engine. This band is known as a tension belt. It's very important after the removal of the alternator that you remember exactly how the belt is twisted because if you replace the alternator and wrap the belt on wrong your car isn't going to run properly, maybe not at all. The Alternator is fixed into the engine very tightly. Disconnect all of the wires that connect the alternator to the engine. They're easy to see. Next, use your socket wrenches to remove the bolts. There should be three of them. You need to loosen the tension belt to get the old alternator out. In order to do this you need to loosen the bolt directly under where the tension belt is wrapped on the alternator. This is the toughest one to remove If you don't have a friend that can help you with the leverage needed to loosen this bolt, the vice grips will come in handy. You can even use a hollowed out broom handle, slide it over your socket wrench and pull from a higher elevation. We actually did this to change out an alternator in an SUV before. The better the leverage, the easier to loosen that bolt. The other two bolts are cake pieces. You should now be able to take out the old alternator. 
  3. The Replacement Alternator. It's just a matter of fitting the replacement alternator into the provided space exactly the way the previous alternator was placed. Connect the wires and screw in the bolts. Now, for the bolt under the tension belt, you don't want to tighten this bolt until you're sure you've positioned the tension belt exactly the way you first saw it. You'll be able to tell you did it right because the belt is so tight, there is no room for errors. You'll have a hard enough time pulling it back in to position the right way. You won't even be able to reposition the belt incorrectly because it wont reach over the designated place on the alternator. After everything is screwed back in, connected, and tightened, the only thing left to do is test it out. Jump the battery. Start your car and see if the charge holds. If it does, then you're good to go. 
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