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JohnGo 06-16-2005 05:58 PM

'01 330ci Alternator Removal
Hey all,

I have to replace my alternator and have gotten to it easy enough (removing the air filter box and detaching the ATF oil reservoir) and it appears that only one bolt holds the alternator on. However, that bolt appears to be attached to or part of the tension pulley. I have searched high and low and haven't found one "n00b" thread for removing the alternator or loosening the pulley.

I have ordered the silly manual for this car twice now, but everyone keeps coming back with "it was sold already" messages, so I am desperately trying to figure out how to get the alternator off so I can have my car back on the road by Saturday... I miss my baby!

Help me OBMWon, you're my only hope! :dunno:


JohnGo 06-16-2005 10:14 PM

Ok... Here is what I figured out on getting the alternator out..
It took 4 hours and breaking my arm in 4 places, but we figured it out. :rofl:

First off, disconnect the battery, negative (black) cable first.

There are dust caps on the pulleys. They are plastic and they pop right off. On the alternator pulley, it covers a 16mm bolt that loosens and just fits past the fan on removal. If you tap the pulley out (towards the radiator) with a rubber mallet, it rotates just off center and releases enough tension to pull the bolt out and get the pulley out of the way. There is another bolt underneath the alternator. Be aware, it is very tight quarters and you should keep a magnet handy, because you will invariably drop a ratchet or a wrench down to the bottom tray. Fun fun...

The tension pulley is just below the one you just removed. There is a bolt head down and to the left of the tension pulley that you can place a long handled wrench on and twist it to release the tension on the belt and pull it off of the main alternator pulley. We couldn't get a socket on it, so we used the two wrench method to get some leverage and turned the pulley enough to slip an allen wrench into a hole that holds the pulley in a non-tension position, making it easier to work in the area. After loosening the bolt on the bottom and using a small pry bar, the alternator twisted up to where we could pull the air intake duct off the bottom and disconnect the cables from the rear. The air intake on the alternator was crammed full of leaves and paper. No wonder it began failing...

You are now holding an alternator in your hands, and have 4 nice, clean breaks in your forearm. :confused:

I will follow up with reinstallation...

JohnGo 06-21-2005 08:23 AM

Now what?
I got the the alternator back from the place rebuilding it only to learn there were no problems with it. They told me the output was right at 14v. The battery is holding a full charge. Anyone have any ideas on what may be causing the drain on the battery?

Some history:
  • When the battery was drained, I had been sitting in heavy morning traffic for about an hour in 72 degree F North Georgia weather. I reached my destination, and had no problems. I went to move the car less than 15 minutes after arriving, and, when attempting to start, learned the battery was dead. I let it sit for almost 8 hours, but it still wouldn't start. We used jumper cables (prior to learning it is not a good idea) and got it running. Upon getting the car restarted, the battery light came on (it was not on before), went off when accelerating, but came back on when letting off the gas or sitting still. Upon reaching the shop, we removed the battery (per specs) and placed it on a charger outside the car. The "eye" was black, which meant to charge the battery according to the label. It charged up to capacity and performed well under load on a load tester. We let it recharge for over an hour and placed it back into the car. The car started up no problem, and no warning lights were on. We tested voltage at the battery and it read 9v, which is what led us to believe the alternator was failing.
  • It is a factory battery and the "eye" is reading fine - no problems.
  • I have not recently installed anything, electronic or otherwise.
  • The car has been sitting more than normal, but has been driven at least 3-4 times a week.
  • The car has just under 85000 miles on it.
  • I have kept all the service items up to date, including the major service items at a local, reputable BMW certified mechanic.
  • The temperatures have been warm and very humid ranging from the high 60s (F) at night to high 80s during the day.
  • I haven't run over anything or taken any damage.
  • Until now, I have had no problems. Of course it is out of warranty, and I am out of work, so any assistance would be greatly appreciated.


hmr 06-21-2005 09:05 AM

Is the battery still the original? If so, 4 yrs is about due for replacement, test results notwithstanding.

JohnGo 06-21-2005 09:30 AM

So far as I know. I bought it about a year and a half ago used.

Also, would that cause a 9v reading when it was just charged and reading reading 12v outside the car?

hmr 06-21-2005 05:14 PM

Sorry, can't answer that. I can only speak from experience (mine died just shy of 4 yrs).

JohnGo 06-22-2005 03:14 PM

Thanks, bro!

I will be working on it again tomorrow and will take it to a parts store and have them test the battery.


hmr 06-22-2005 03:26 PM


JohnGo 06-24-2005 10:23 PM

Just a quick FYI to those intending to tackle this themselves. DO NOT apply any pressure whatsoever to the pulleys. They are plastic, and they are brittle. And if you have to replace one, they are not priced nearly as cheaply as they are made. $42 retail from dealership, $20 if you have a friend that works at the dealership and can manage the 10% over cost employee pricing discount. I highly recommend the friend pricing. :tsk:

I am not one to normally complain about pricing, but over 200% markup on a cheap piece of plastic annoyed the crap out of me.

Nice markup there, guys. :thumbdwn:

JohnGo 06-25-2005 10:38 AM

Houston, the Eagle has landed... sort of.
Ok. Good news...

After replacing the broken power steering pump pulley, the alternator went back in fairly easily.

The bottom bolt is a royal PITA (Pain In The Arse) unless you make sure to do the following: While the alternator is out of the car, you will notice a pressed in bushing with a threaded hole and a hex head on the rear side of the alternator for the bottom bolt to thread into. Take a socket that is the slightly smaller than the bushing and carefully tap it out a fraction of an inch (no more than a 16th of an inch) towards the back of the alternator. The reason for this is when you try to replace the alternator with it fully pressed in, it is an extremely tight fit and you can't really move the alternator around to line the holes up. By pressing that bushing back out a little , you will regain the ability to move the alternator with ease and get the bolt back in without cursing the Germans, their cars, and their engineering. :) The bushing will then pull back to its original position when you tighten the bottom bolt.

Everything went back in easily after that. The car started up with no issues and ran fine, but the battery did die again on my way home from Advance Auto (battery light comes on, as well as every other light on the dash). They didn't have a replacement in stock, so I will have to try the Autozone 49-DL replacement mentioned on another post.

The good news is Radio Margaritaville is finally live on Sirius Satellite Radio and I got to listen to it for a couple of songs before the battery went into cardiac arrest again. :banana:

hmr 06-25-2005 11:16 AM


Originally Posted by JohnGo
...and get the bolt back in without cursing the Germans, their cars, and their engineering. :) ...

:rofl: Been there, adding the designer and his/her mother to the list :eeps: (whosever product it happened to be, German or not)...

JohnGo 06-26-2005 09:25 PM

Still cursing the Germans!
Took the battery in, and it is fine. No dead cells. Holding charge under load outside the car. However, place it back in and run the A/C, it is sucked dry like an unknown extra on Buffy. :banghead:

When we checked the output charge at the battery before, it was a 9v. Now it is reading well over 16v. Anyone have a clue what has suddenly possessed my beautiful automobile??? She is headed to the shop on tuesday. I can't take it anymore. My wife's Z3 is fun, but it is not my nice quiet, comfortable 330ci. :mad:


JohnGo 07-16-2005 11:48 AM

Interesting chain of events...
After taking the car in to the shop, it turns out the battery WAS bad, and it killed the regulator on the alternator. So after replacing the battery and the alternator (he offered to replace just the regulator, but said at 85k, the alternator would have to be replaced sometime in the not-too-distant-future anyway), it is running like a top.

On a sidenote, I asked my mechanic about the Autozone battery and he said he actually recommended the same battery for people until 4 cars showed up back in his shop less than a week after replacing the factory battery with the Autozone battery. He hated to do it, but recommend the factory battery. More expensive, yes. Works, yes. Sometimes it is just easier to eat the pain...:yikes: lol

RonaldRegan 07-23-2008 05:14 AM

This thread helped me a lot with replacing the alternator in my '02 325i. THANKS!!! I thought I'd share some tips from my experience.

You will undoubtly loose/drop a bolt or tool while doing this. It is really easy to remove the cover under the engine and highly recommended so that the bolt or tool fall to the ground instead of trying to fish it out. The cover comes off with 7 one turn screws and 3 plastic rivets, very well designed to remove and re-install easily.

Also, an easy way to lock the belt tensioner to relieve to pressure is to just pull on the belt once you remove the top bolt/pulley of the alternator. This will position the tensioner so that you can place something in the two holes and lock it in position.


fotoholt 11-24-2012 02:45 PM

This thread has great information. I have a 2003 540i that has recently had some battery issues. I replaced the battery in May. It appears to not be holding a a charge - specifically overnight. I checked the Alternator output while running and it is at 13.5v when idling. I am thinking this is a bad battery. Any ideas?

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