Results 1 to 14 of 14

Thread: Vibrations, noises - at various speeds

  1. #1
    Join Date
    Dec 2018
    Location
    San Francisco
    Posts
    141
    My Cars
    ‘81 E21 320i

    Vibrations, noises - at various speeds

    Any hints for dampening vibration sounds? I hear one that seems like it’s coming from the parcel shelf, but sounds like the thin heat shield on my old pickup.

    Thanks in advance.

  2. #2
    Pelican Parts's Avatar
    Pelican Parts is offline Senior Member Supporting Vendor
    Join Date
    Aug 2013
    Location
    Harbor City, CA
    Posts
    4,242
    My Cars
    '02 E39 Touring
    Hello - you can try products like Dynamat and Hushmat.
    Your Trusted Source For DIY and Parts
    FREE SHIPPING over $99 click here
    BMW Parts | DIY Tech Articles | Facebook | Twitter | Instagram | YouTube | Promos
    888.280.7799 | 6am - 5pm PST



  3. #3
    Join Date
    Feb 2016
    Location
    Sacramento, CA
    Posts
    1,077
    My Cars
    1979 E21 320i
    Metal on metal is strange to have in that area because just about nothing is back there that could make the noise. Did someone maybe add a bracket underneath it for an aftermarket amp or something? That'd be my first guess
    -John

  4. #4
    Join Date
    Jun 2016
    Location
    Austin, TX
    Posts
    1,585
    My Cars
    1978 323i
    Loose speakers? Panel clip popped loose? Loose rear seat back screws letting it vibrate? Perhaps pull the rear seat and speaker panel and drive around to see if the sound goes away?

  5. #5
    Join Date
    Feb 2005
    Location
    Vermont
    Posts
    2,588
    My Cars
    81 320i, 98 318ti
    I'd suspect the exhaust heat shield, either in the back by the muffler/halfshafts or the one between fuel tanks.

    Max

  6. #6
    Join Date
    Dec 2018
    Location
    San Francisco
    Posts
    141
    My Cars
    ‘81 E21 320i
    Quote Originally Posted by mxl556 View Post
    I'd suspect the exhaust heat shield, either in the back by the muffler/halfshafts or the one between fuel tanks.

    Max
    You know, that’s what I started to suspect.

    The other noise above 65 is a hum. I think dynamat on the firewall and floor will quiet that.

  7. #7
    Join Date
    Dec 2018
    Location
    San Francisco
    Posts
    141
    My Cars
    ‘81 E21 320i
    1981_bmw_320i_1543801871ef66e7dff9f98764daIMG_5976.jpg
    Do the flanges with threaded holes suggest anything that might cause more vibration?

  8. #8
    Join Date
    Feb 2005
    Location
    Vermont
    Posts
    2,588
    My Cars
    81 320i, 98 318ti
    No these flanges are for a little heatshield that is missing.
    There is a pipe heatshield in front of it that is tack welded to the pipe and often starts rattling when gets hot.

    Hum sounds like like tire noise or a wheel bearing. Could be a differential too. Nothing should be making humming noises and "fixing" it with dynamat is not a solution ( it will not quiet it down much anyway).

    Max

  9. #9
    Join Date
    Dec 2018
    Location
    San Francisco
    Posts
    141
    My Cars
    ‘81 E21 320i
    It 'hums' at 65 mph or above, at 3500 rpm or above. Really like a harmonic frequency from the engine. I hear nothing at all at lower speed.

    I do have doubts about dynamat.

  10. #10
    Join Date
    Feb 2005
    Location
    Vermont
    Posts
    2,588
    My Cars
    81 320i, 98 318ti
    M10 itself is noisy and kind of "hums" above 3500 PRM... Hard to diagnose without hearing it. If it's speed related then it could be tires, wheel bearings, driveshaft, differential or transmission (unlikely especially for auto). Noise of the wheel bearings and tires change depending on turning.

    If it's RPM related than it has to come from the engine.

    What did you drive before this e21?


    Max

  11. #11
    Join Date
    Dec 2018
    Location
    San Francisco
    Posts
    141
    My Cars
    ‘81 E21 320i
    '79 VW Rabbit diesel. That is loud!

    I had wheel bearings go bad - I'd describe it more as a 'whirring' noise than a hum.

    Could be the drivetrain, though. Like the diff, but I think it's the engine and exhaust.

  12. #12
    Join Date
    Jun 2016
    Location
    Austin, TX
    Posts
    1,585
    My Cars
    1978 323i
    When I've had bad wheel bearings one thing I noticed was the sound would be more or less noticeable when I was turning right or left.

  13. #13
    Join Date
    Dec 2016
    Location
    Atlanta Ga
    Posts
    127
    My Cars
    98 M3 Sedan, 82 320i
    I have been trying to figure my road noise above 65 mph out also. Old post below
    https://www.bimmerforums.com/forum/s...ar-Wheel-Noise
    Could be rear bearings ?

  14. #14
    Join Date
    Jan 2019
    Location
    Canada
    Posts
    25
    My Cars
    f10 535ix

Similar Threads

  1. E46 AC Dashboard Vibration Noise / bump - low speed AC
    By eben12 in forum 1999 - 2006 (E46)
    Replies: 0
    Last Post: 07-16-2011, 09:46 PM
  2. Whistling noise at high speeds?
    By NiTE in forum 1992 - 1999 M3 (E36)
    Replies: 9
    Last Post: 06-19-2003, 05:09 PM
  3. Vibration noise @ 2500rpm!!!!!!
    By petermilinou in forum 1992 - 1999 M3 (E36)
    Replies: 4
    Last Post: 02-12-2003, 06:49 AM
  4. Hissing noise at low speeds
    By RightM3 in forum 1992 - 1999 M3 (E36)
    Replies: 6
    Last Post: 08-23-2001, 01:52 AM
  5. Clicking/vibrating noise coming from E-brake in rear
    By Jim//M3 in forum 1992 - 1999 M3 (E36)
    Replies: 1
    Last Post: 06-06-2001, 08:49 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •