Sunday, July 10, 2011

How to replace the alternator in a 1996 328is BMW

4th of July weekend was supposed to fun filled with family time and lots of wakeboarding and great food. Unfortunately, on our way up to Lake Almanor we ran into some car problems. Turns out it was the alternator that decided it just wasn't going to work anymore. At first we didn't know what was going on until the car just completely died on us.

What does the alternator do?
The alternator is the part that keeps your battery charged. It works with the battery to keep the electronic components of your car working. Here is a great article about everything you need to know about alternators :)

What are the signs of a failing alternator?
If your alternator is failing you will initially start seeing your electronics go out. For example, as we were driving the radio started cutting out and then went out completely. After that, the cruise control went out, then the lights on the climate control panel, the ABS (antilock break) light came on signaling that the ABS was not functional, then the entire instrument panel with the spedometer and odometer went out. Finally the car will just shut off and you will be left with a powerless car. No interior lights, no headlights, nothing.

What to do if you are driving when the alternator starts failing?

The best thing you can do is pull over immediately and call either AAA or another agency to come tow you home. If that isn't an option (for us we don't have any towing covered by insurance) you can call a friend or relative to come jump start your car, let the battery charge for a good while and try to make it home on that charge. It's really bad to jump the car, drive it, jump it again, drive it, etc. That's what we did since we were about 30 minutes away from home and it is really really really bad for the batteries of both cars, but like I said, if you have no other choice then go for it.

How to replace the alternator:
In my 1996 328is BMW it was fairly simple. Generally alternators aren't in tough spots to get to so as long as you can find it this DIY should be somewhat helpful.
1996 BMW Alternator
First step is to remove the air box housing which is what Jeremy has his hand on in the picture above. He removed the two bolts that were holding it in place and then it easily just lifted out of the car.

1996 BMW Alternator
After removing the air box housing you should see the alternator in a fairly accessible spot. 

1996 BMW Alternator
There were two large bolts holding the alternator in, one was easy to reach the other not so much.
1996 BMW Alternator
Remove the belt that is on the alternator and get one of the small socket wrenches in order to reach the bolt. See how Jeremy's hand is all awkward in the picture above? That's where the hard to reach bolt is located.

1996 BMW Alternator
Once the two bolts are off and you pull the alternator off, you will have to remove the electrical connections which you can see has been done above. There are two bolts holding the connections on and are very easy to remove.

1996 BMW Alternator
There was a butterfly inside the alternator along with some leaves and dirt. Those aren't why it died but it doesn't help the cause either :)

1996 BMW Alternator
Here is what the engine looks like with no alternator.

If you have the ability to get a replacement alternator from a mechanic or a BMW dealer I would suggest doing that but if it's the weekend and you have to go to Autozone, they should carry one that works in your car, even though it might not be the best quality. They do have a lifetime warranty on the alternator at Autozone so if they do sell you a crap part, it won't cost you anything to replace. We took the old alternator in and got $90 off (the copper cores are valuable).

1996 BMW Alternator
Here is the pretty new alternator ready to be put into my car. The tougher bolt doesn't work in this alternator because of the threading so Jeremy just improvised a little bit. To put it in there just do what you did to take it off, only in reverse (obviously). Jeremy stuck it back in there and it stayed without any bolts holding which was really nice so I didn't have to get my hands all grimey trying to hold it in there while he put the bolts back in.

Once we got everything back in place we had to jump the battery to get the car started and drove around for about an hour to let the alternator do it's job and juice up the battery a bit. After that drive there haven't been any problems with the battery or alternator. The blower on the other hand...I'll save that for a later post :)


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  5. I stopped by your blog today.
    Hope everything worked out.

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    Helpful tip I wish I had a BMW.

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