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Thread: DIY: Additional info on E46 alternator replacement

  1. #1
    Join Date
    Aug 2010
    Location
    Nanjing, China
    Posts
    153
    My Cars
    2011 328xi

    DIY: Additional info on E46 alternator replacement

    First question: how did I know that I should replace my alternator? Or, how am I sure that alternator is the cause of my problem?
    Here is what happened to me:
    My battery light was on. After driving for about another 10 minutes, my DSC, ABS, and Brake lights were all on. So I pulled over and shut down the engine to take a look. Then when I tried to start the engine again, the engine did not start.
    Then after doing some research, I tested the battery output voltage, which was 12.2V. But when I read the alternator voltage, it was only 11.8-11.9V. For "how do I know the battery and alternator voltage?" question, please seach BMW OBD II codes, or something like that.
    Simply, alternator output voltage should be higher than battery voltage, because otherwise the battery will not be charged. For example, my new alternator output voltage is 14.7V.
    At that time, when I saw my alternator outputting a lower voltage than my battery, I decided to replace my alternator.


    Then, 2 weeks later:
    OK, finally I am back reporting the alternator replacement on my 2001 E46 325CI
    The procedure is pretty much the same with many diy from various internet resources. So I will be brief:
    1. remove your airbox
    2. remove the ATF oil box, not sure what it is, because it gets in the way you work
    3. remove the positive 17mm hex connector and the clip connect on the back of the alternator
    4. remove the 16mm hex bolts, one on top, the other on bottom of the alternator.
    5. take off the alternator, and put on the new one.
    6. put on all the bolts you took off.

    Some information I think might be helpful:
    followings are for taking off the alternator
    1. I think it is always safe to disconnect battery when working on cars. I disconnected my negative connector.
    2. You do NOT need to take off fan shroud and fan clutch to get this work done. I guess it also depends on if you have big hands. My hands are not big, but they got some scratches.
    3. You need long socket for hex 16mm and hex 17mm. The length is about 2 inches, so that you don't have to remove the fan.
    4. Take off ATF oil (not sure what it is, transmission? power steering?) container. It is round shape, it is located right next to the oil filter container. Taking off the ATF oil container gives more space to work.
    5. The bottom mounting of the alternator could be tight. But you should be confident that it can be taken off if all connections (two 16mm hex bolts on front, one 17mm hex bolt and one clip on back, circled in following picture) are removed. If it is too tight, rotate the alternator about the mounting axis a couple of times, and try to rotate it more clockwise (assume you are standing in front of the car facing the driver). It will be released eventually.


    Thanks for the pictures to
    http://www.bimmerfest.com/forums/sho...d.php?t=422843

    6. When you take off the alternator, the belt has to be removed anyway. But it is important to remember how the belt go through/around all the pulleys. Never mess it up. Here is an image that might be helpful: (Apparently, there are two belts. You only need to remove one of them)

    Source: http://3.bp.blogspot.com/_5uMhjpyGUS...eltdiagram.png



    Followings are for putting back
    1. First you can put back the alternator. Bottom bolt (front) first, then the top front bolt together with the idler pulley. There is a knocking pin (see following picture) on the idler pulley, make sure it stick into the notch on the alternator. Make sure everything is tight. These things rotate thousands of times per minute.

    Source: http://i01.i.aliimg.com/photo/v0/296...36_E46_E34.jpg
    (seems they call it tensionor pulley, but I call it idler pulley, same as that in picture in 6th step in taking off procedure above.)

    2. Put on your belt, making it go its way correctly (if you forget, see picture above), but only miss the alternator.
    3. Now you need to detension the tensionor to let the belt go through the alternator. It is good to know what tensionor you have because there are two types of tensionor: mechanical and hydraulic. MINE IS DYDRAULIC!! (I think mechanical is easy, you need a 16mm hex socket to detension it). You need a 8mm hex bit (not a socket) to turn it. Remove the dust cap, then stick your 8mm hex bit into the center (circled in yellow in following picture. It is a HYDRAULIC tensionor!) of the tensionor, then turn it clockwise. The torque is big, you need a long arm ratchet to turn it. DO NOT turn the hex bolt circled in red, if you want to detension a hydraulic tensionor!



    I think that is all I can share. I guess everything else is easy.

    Good luck with your diy, and many thanks to those on this forum who selflessly shared their opinion for my work.
    Last edited by nickxtsui; 03-05-2012 at 03:49 AM.
    Why am I always getting some code?

  2. #2
    Join Date
    May 2013
    Location
    Canada
    Posts
    1
    My Cars
    2001 325i
    Thank you very much for the info, was a great help for the hydraulic tensioner, I was a bit lost. I did however loosen bolt to the left (one with the big X through it) and tightened it. You sounded pretty clear not to do this. Will this have any effect, or is it simply for the removal of the tensioner? thanks again

  3. #3
    Join Date
    Oct 2004
    Location
    Ayr, ND
    Posts
    1,521
    My Cars
    2001 330i
    This may also help:BEFORE ATTEMPTING AN ALTERNATOR REMOVAL OR SERVICE FIRST UNPLUG THE NEGATIVE TERMINAL OF YOUR CAR'S BATTERY!!!!!

    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:

    http://youtu.be/QUDVVKUB180


    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:

    http://youtu.be/6cQUd5BZtdA


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



    See video.

    http://youtu.be/KJuuAIddrl8

    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.



    *DISCLAIMER:
    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 24MM Socket (1/2" is good), one M10 x 50MM bolt (1" to 1.25" long), a pack of large flat 3/8" M10 steel washers ($12 total at AutoZone).



    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; 12-09-2013 at 04:15 PM.


    VISIT MY GARAGE TO SEE ALL MY MODS:

    http://directory.e46fanatics.com/use...rMod&UcId=7917

  4. #4
    Join Date
    Oct 2006
    Location
    London, UK
    Posts
    288
    My Cars
    '00 330Ci, '07 350Z
    Good info on the lower mounting bolt, thanks Will save me some head scratching
    E46 330Ci: Umnitza P46 Headlights + Custom LED Halos; Eagle Eye smoked taillights; LEDs fogs; M3 bonnet conversion; M-Sport Front & Rear bumper; Replica M3 mirrors: Rear lip spoiler; Carbon fibre strut brace; Aluminium rear strut brace; H&R Sway Bars; LSD 3.15 ratio; F30 front & rear Brembo BBK conversion; ECU Remap; F32 Front Seats; GROM Audio

  5. #5
    Join Date
    Jan 2010
    Location
    Minneapolis, MN
    Posts
    1
    My Cars
    540i,330xi,325xi
    I just did this repair on my 2003 335i. I'll share what went wrong first:
    1) Working from the front, I ended up tightening (instead of loosening) the positive terminal bolt which, as it turns out is a plastic 16MM bolt, that covers the metal nut that actually holds on the positive terminal. After figuring out that freshman mistake it was smooth sailing.

    I had no problems with the rear alternator bolt locking mechanism on my car. Rocking the alternator out front first worked.

    2) I didn't check the belt routing when putting the belt back on and went over the idler pulley instead of under. The result was too much tension and poor engagement with the alternator causing the belt to overheat. Check alignment diagram before proceeding.

    If you have the hydraulic tensioner use a Torx T50 bit (I had picked up one somewhere in the past as it was hanging out in the socket set). Mine has a 3/8" drive but that was sufficient to de-tension the belt. Again, turn clockwise to de-tension. The T50 head looked like it was pretty rusty and worn but it didn't slip.

    Krauboy

    - - - Updated - - -

    I just did this repair on my 2003 325i. I'll share what went wrong first:
    1) Working from the front, I ended up tightening (instead of loosening) the positive terminal bolt which, as it turns out is a plastic 16MM bolt, that covers the metal nut that actually holds on the positive terminal. After figuring out that freshman mistake it was smooth sailing.

    I had no problems with the rear alternator bolt locking mechanism on my car. Rocking the alternator out front first worked.

    2) I didn't check the belt routing when putting the belt back on and went over the idler pulley instead of under. The result was too much tension and poor engagement with the alternator causing the belt to overheat. Check alignment diagram before proceeding.

    If you have the hydraulic tensioner use a Torx T50 bit (I had picked up one somewhere in the past as it was hanging out in the socket set). Mine has a 3/8" drive but that was sufficient to de-tension the belt. Again, turn clockwise to de-tension. The T50 head looked like it was pretty rusty and worn but it didn't slip.

    Krauboy

  6. #6
    Join Date
    Jun 2013
    Location
    Miami
    Posts
    30
    My Cars
    BMW 328ic 1998
    Thank you for your detailed explanation on how to remove/replace the alternator. I was able to remove it with some wiggling but impossible to place back into the hinge with the rear passing nut all the way in. This nut was frozen on my alternator. After 2 hrs of PB Blaster and gently tapping I was able to barely move the passing nut out but enough to put it back in the hinge. Next time the alternator is out I will try the extraction method with the 50mm bolt from behind. And put anti seize on the nut before replacing it!

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