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Thread: Bad Belt Squeal, New Belt and Pulley - Am I Missing Something?

  1. #1
    Join Date
    Sep 2011
    Location
    Mokena, IL
    Posts
    144
    My Cars
    '02 325iT, '83 320i

    Bad Belt Squeal, New Belt and Pulley - Am I Missing Something?

    I have a really bad belt squeal that appears after driving after 10-15 mins or so. Belt has been replaced, alternator and pulley have been replaced, belt pulled taught - still squeals. It looks like the alternator is moving under the torque of the belt and I'm now beginning to wonder if I'm missing something to give the mounting "arm" for the top alternator mount more rigidity. When I pull back slightly on the alternator (towards the rear of the car) the squeaking stops. I was looking at a diagram on realoem.com and it seems I'm missing parts #21 and 22 see here.


    At the risk of sounding completely incompetent, can anyone here confirm whether this is a necessary part(s) for the alternator to be mounted correctly? The only other e21's I've seen in person have been swapped or it was a part out, otherwise I would have made note. If so, does anyone have any spare parts to sell? Also, if someone has a picture of their own alternator setup, I'd really appreciate it!

    Attached are images of the arm I'm referring to and how my current setup looks.

    Thanks in advance!

    IMG_9024-1.jpgIMG_9025.jpgIMG_9026.jpg

  2. #2
    Join Date
    Oct 2015
    Location
    RI
    Posts
    1,052
    My Cars
    1983 320is S52/2003 VR6T
    Those parts are designed to lock it in place. I would not be shocked if the bolt was sliding and causing the squeaking.

  3. #3
    Join Date
    Jun 2019
    Location
    LaGrange, GA
    Posts
    154
    My Cars
    1983 BMW 320i
    An issue with alternators on these cars is the soft rubber bushing in the alternator mounting holes. It flexes and torques the belt. Options are polyurethane bushings, slotting the back nut recess to torque it back, or running your alternator not as tightly.
    Hope this helps, JB

  4. #4
    Join Date
    Nov 2010
    Location
    GREECE
    Posts
    135
    My Cars
    1983 E21 315
    Quote Originally Posted by okieflats View Post
    The axis of the alternator needs to be parallel to the axis of the engine crankshaft. And the pulleys need to be in the same plane, meaning like their distances from the radiator need to be equal.

    You alternator really looks to be tweaked at an angle. Which probably is the rubber bushings as mentioned in the post before mine.

    +100 I had the same problem with my old E21.It ended be bad rubber bushings....

  5. #5
    Join Date
    Mar 2013
    Location
    Santa Rosa, CA
    Posts
    1,631
    My Cars
    1981 320i silver
    I tried to remove that alternator bracket from my parts car, so I could better understand how it is mounted and the rubber bushings. What a PAIN IN THE ASS. Still didn't get it off. One bolt holding it is under the oil filter, impossible to see, next to impossible to get a wrench on.

  6. #6
    Join Date
    Mar 2013
    Location
    Santa Rosa, CA
    Posts
    1,631
    My Cars
    1981 320i silver
    Screenshot (114).png

    Have to take the oil filter part off the block first.



    - - - Updated - - -

    Screenshot (115).png


  7. #7
    Join Date
    Jun 2016
    Location
    Austin, TX
    Posts
    1,585
    My Cars
    1978 323i
    In case you didn't already figure this out, the bushings are in the ears of the alternator itself, not the bracket.

    Poly bushings are a permanent solution.

    Squeezing the new ones in can be a little hard, they fit pretty tight - clean out the hole really really well with a wire brush or scraper even to remove any remnants of the old rubber bushings. Lube up the new ones and squeeze it all back together with a couple sockets of appropriate size in a vise, you'll need to get it all together tightly enough to get the C-clip back on the metal sleeve.

  8. #8
    Join Date
    Mar 2013
    Location
    Santa Rosa, CA
    Posts
    1,631
    My Cars
    1981 320i silver




    I wonder if the op could be using a bolt that is too small in diameter, or is missing that metal sleeve that is held in by that circlip in the picture.

    His alternator is more crooked than mine, either of my 2, and they are both old, old bushings, etc.

    - - - Updated - - -

    I found the third bolt that was holding the oil filter part on. I couldn't see it in the dark last night. Besides it was covered in oil, dirt, grime. Once i got that off, removed the oil filter, then removing the alternator bracket was easy. But the 3rd bolt for the alternator bracket is virtually inaccessible without removing the oil filter.

  9. #9
    Join Date
    May 2012
    Location
    FL
    Posts
    526
    My Cars
    E83, E21
    Mine is all original, purchased from the original owner, and did not have the adjustment bar with the adjustment "star." I typically use a pry bar to get the tension I need.

    Agree, that hidden 3rd bracket bolt is a pain; IIRC I held the nut with an open end 13mm and used a ratcheting 13mm to loosen the bolt. I removed the oil filter adapter anyway for more clearance and to clean/paint it; not a bad idea to replace a 40 year old weeping gasket, either. The alt is a pretty tight fit (I had to use a rubber mallet to remove/install it) in the bracket. IIRC there are some flared inserts in the bracket that space/squeeze the alternator for a tight fit (but don't quote me, I could be remembering a different vehicle). That crooked alt definitely looks like something assembled wrong.
    E21 build

    BMW CCA 584213

    I buy socks from Amazon.

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