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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 12-06-2013, 03:47 AM   #1
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Cool DIY: How To SAFELY Remove Your BMW E46 Alternator in 10 Easy Minutes!


This write up is for those who have ALREADY removed the car's engine bay air box, engine bay fans, engine belts and now you have gotten to the Alternator and you are stuck on why it remains seized onto the car even though you have removed the two bolts and spent all day wrestling and prying at it.

I explain why BMW E46 Alternators don't come loose even after unbolted and pried before showing how to get an Alternator out of your BMW E46 M54-engine car in 10 minutes or less.*

Tools Needed for this DIY:

1 - One Soft Rubber Mallet ($5 at AutoZone for the 16 ounce one)

2 - One Small Handle Sturdy Ratchet. Once you get the Alternator bolts loose with the Long Handle Ratchet or Breaker Bar use this short handle ratchet to finish un-threading the bolts.

3 - One 16MM 1/2" Socket: ($1 to $5) Socket-to-Ratchet Adapter Sets and Extensions ($2 and up) help as well. You will also need a 17MM Socket to remove the rear nut that holds the battery cable to the back of the Alternator. Remember to UNPLUG the battery in the trunk before doing this.

4 - One Medium to Long Handle Ratchet or 12" to 20" Breaker Bar: Works with 16MM Socket to release Alternator bolts. If you suspect your Alternator bolts will be tightly seized to the car get a 12" to 20" long Breaker Bar ($10 to $15)

5 - One clean Pick Axe - NOT REQUIRED BUT HELPFUL ($20 at Home Depot buy-use-return or borrow one from a friend). This is NOT a substitute for a Pry Bar. I did not use a Pry Bar since I found the Pick Axe to be safer and easier to use than a Pry Bar when it came to 'lifting' the Alternator off the lower mount. I repeat the Pick Axe is NOT A SUBSTITUTE for a Pry Bar.

Things Not Required for this DIY:

- An Ounce of Sweat
- Muscle
- Good Old Elbow Grease
- Alternator Removal anxiety, fear and frustration.

Part 1 -Explaining how the Alternator is mounted in the car:

1. The Alternator's top bolt 16MM is straightforward. You remove it and the Alternator's connection at that bolt is COMPLETELY freed.

2. The Alternator's lower 16mm bolt is NOT straightforward. The bolt's front mount hole is a normal pass thru hole. The bolt's rear mount hole where the bolt threads into is a sliding nut.

This sliding nut slides FORWARD inside the mount hole when the bolt is tightened at the time the Alternator is mounted in the car. The effect of the nut sliding forward is to LOCK the Alternator into place onto the mount.

Here are two pictures showing the bottom mount holes with the rear mount hole's sliding nut 'open' and 'closed'/locked.

3. The issue now is when removing the lower bolt the sliding nut (also called the "holding nut") usually remains in the closed position AFTER the bolt has been removed. So the Alternator is going to be still locked onto the mount after the bolt is removed.

SOLUTION: The technique that worked for me is the "Bolt Tap" method.

After I removed the lower 16MM bolt I inserted it back into it's hole and pushed it all the way back to the rear mount's holding nut.

I threaded the bolt back onto the holding nut using my fingers (about 3 to 4 turns). With the bolt threaded onto the holding nut I began to tap the bolt's head back gently a few times with the Mallet. With the fan out of the way you will have enough clearance to tap at the bolt head firmly. If the mallet head is to broad to reach and strike the bolt head properly then use the small handle ratchet/16MM combo to brace between the bolt and the mallet.

Tapping the bolt back works to loosen the holding nut at the rear lower mount hole thus pushing it backwards into an 'open' position that will free the Alternator.

See video:

Part 2 -
A few firm and gentle taps will push back the holding nut off the mount either all the way or enough to where you can wiggle the Alternator free.

The way the rear holding nut pinches the mount requires the Alternator to be lifted upwards from the front while the rear end remains down in order to free it. If using your hands pull up on the front while keeping the rear end down (but you are still lifting up the rear end at the same time) and wiggling the body laterally side to side to free the beast from it's nest.

The way the Alternator sits and how it's pinched onto the rear lower mount hole via that sliding nut makes a Pry Bar (or long sturdy Philips screw driver) tricky to use. Having an extra set of hands to wiggle the Alternator free while you pry it up may help but my DIY is a sweat free/buddy free DIY so keep reading.

To keep this DIY under 10 minutes get your Pick Axe (again this is NOT a substitute for a pry bar) and get to work. See video:

Part 3 - With the Alternator out the car I am explaining how the bolt tap technique works.

See video.

When replacing the alternator with a brand new one you will not have an issue with the mount hole rear sliding nut being closed. It should be open. If reusing an old or re-manufactured/refurbished Alternator the sliding nut may be closed. To open it you can use the bolt tap technique before mounting the alternator to your car. You should use anti seize lube on the the new bolts and if possible the contacts point of where the incoming Alternator will mount onto your car.

This will make future removals a breeze.

Although I thought it was safe to use this method I still want to disclaimer that I went into this DIY not needing to re use the old Alternator and bolts since I was replacing a dead Alternator with a new one. That said, I didn't care if I damaged the old Alternator taking it out.

However in retrospect and by reviewing the technique I used and realizing no damage was done to the old alternator, bolts and engine bay the Mallet and Pick Axe technique would be perfectly safe and effective for those following my instructions as stated below. Although the video instructions are clear as day (a brain dead monkey can follow what I am doing) I am not responsible for your attempts to follow this DIY and any damage you may do to your car.

Honorable Mention for Alternative Alternator Removal:

Some folks have devised another way to get the Alternator out by tacking the lower mount's rear holding nut another way.

Buy these items: one 1/2" 24MM Socket, one M10 x 50MM bolt (1" to 1.25" long) with a 1.5mm standard thread pitch, a pack of large flat steel washers with a center hole wide enough for the bolt to pass through and wide enough to lay flat against the back of the socket

After the two Alternator bolts have first been removed you will go to the back of the Alternator where from behind you will place a 24MM socket over the lower mount's rear holding nut. The holding nut will protrude slightly at the back find it and place the socket over it.

Then over that 24MM socket place a couple of washers (4 to 5) and after insert the M10x50MM bolt in thru the center hole of washers and the 24MM socket. Then get the tip of the bold onto the holding nut. Begin threading the M10x50MM bolt into the holding nut using a small ratchet/socket combo or wrench. Keep turning the bolt.

The washers and socket ONLY serve to keep the bolt stationary as it threads into the holding nut. Since the bolt is stationary and not moving into the holding nut as you turn the bolt it is the holding nut that moves outwards inside the 24MM towards the bolt.

Keep threading the bolt into the holding nut and the result of this will pull the holding nut outwards into the OPEN position freeing the alternator.

Here is an 'x-ray' example picture example of how the M10 x 50MM bolt looks on the holding nut (remember the 24MM Socket and washers will have to be in place over the M10 x 50MM bolt for this technique to work):




Last edited by delmarco; 12-21-2013 at 05:03 PM.
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Old 12-09-2013, 11:02 AM   #2
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Will not need this (hopefully) as my alternator was replaced two years ago. That being said, this is a great DIY! I compliment you for figuring out this method and taking the time to share with all here.

Two thumbs up!
I love my car as much today as the day I bought it
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Old 12-09-2013, 05:32 PM   #3
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I updated the write up to show the rear attack technique that uses the M10 bolt and 24MM socket/with washers to pry loose the rear holding nut.



Last edited by delmarco; 12-09-2013 at 05:38 PM.
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Old 12-09-2013, 05:51 PM   #4
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DIY: How To SAFELY Remove Your BMW E46 Alternator in 10 Easy Minutes!

Excellent write up, will need this to service the alternator soon.

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Old 12-09-2013, 07:28 PM   #5
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Originally Posted by delmarco View Post
5 - One clean Pick Axe

BMW MacGyver.

Great writeup Delmarco. I'm saving this one. When I replaced the alternator on my 330ci I made up a few new curse words while getting it lose.
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Old Yesterday, 09:44 AM   #6
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Wow, great documentation for guys like me that don't have a clue until we can find a thread that has pictures or threads.
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