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Thread: '01 525i Touring Air Suspension still leaks after new Air Spring replacement

  1. #1
    Join Date
    Jul 2003
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    '96 328i; '13 X3

    '01 525i Touring Air Suspension still leaks after new Air Spring replacement

    My '01 525i touring wagon has about 110k miles, and recently I found out that when the car was parked overnight, the rear suspension will sag. Most of the time it's the driver side, sometimes it's both sides. But the driver side is the most severe where the car will sit on the bump stop while the passenger side will sag just a little bit. But once my car is running, the pump maintains the air springs at the correct ride height so it drives fine.

    Then following the logical approach, I replaced both bags (mine is the sports edition, I made sure the new part number matches my old one. 37121095081 and 82.). But the problem is the same as before: Driver side completely sags to bump stop after overnight parking, passenger side sags just a little. Once the car is running, the ride height is correct on both sides.

    I am just wondering what else could be leaking and how to check the leaks. Could those red and blue gaslines from the pump be leaking somewhere? Or can the reservoir be leaking? Any ideas? Thanks!

  2. #2
    Join Date
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    2000 BMW 528iT/5 SC
    You need to test all your air line connections including the ones under the air pump cover and near the module to the right side of the spare tire. Put a little dish washing soap in a cup with some water. Then, with an inexpensive paint brush, brush this liquid on all the connections and wait. If a grouping of bubbles grows at a connection, you've found the leak(s).
    Much modified VF Supercharger Kit tuned by Tuning Tech FS, M5 front sports seats, CVV to catch can conversion, Boost Gauge, Schmiedmann header to rear muffler high flow exhaust, Header Ceramic coated inside & out, Exhaust heat wrapped from flanges after header to before CATs, Kicker sub with dedicated 200 watt amp, CCFL angel eyes, CF facelift kidney grills, Quaife LS diff ,Super duty cooling kit, Electric fan controlled by temperature adjustable 2 speed controller (JimLev design)

    John

  3. #3
    Join Date
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    Quote Originally Posted by jstern View Post
    You need to test all your air line connections including the ones under the air pump cover and near the module to the right side of the spare tire. Put a little dish washing soap in a cup with some water. Then, with an inexpensive paint brush, brush this liquid on all the connections and wait. If a grouping of bubbles grows at a connection, you've found the leak(s).
    I took out the spare tire wheel well cover and expose the pump and controllers. I used the soap water to test all the pressure gas line connections for the driver side (red line), but couldn't find any bubbles. For one thing, this leak is very slow, it take about one night (10 hours) to drop 1-2". I am wondering whether I should just go ahead to replace the red pressure plastic line as well as all its connectors. Any thoughts?

  4. #4
    Join Date
    Oct 2004
    Location
    Falls Church, VA
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    1,039
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    '90 325iX, '00 528iT spo
    The red and blue lines from the air junction box to the "clam shell" (solenoids / pump) and the top of the air springs are only some of the lines.

    Each air bag has a large air tank reservoir under the car.

    Each air reservoir under the car has a ~ 1/2" hard plastic air line going from the reservoir up through the body to the brass junction block on the top of each air spring.

    I have replaced one of these.

    In doing so I noticed that the connections for these lines are heat formed (shrunk) onto the brass & metal connections. These pieces could pivot and were loose on the air reservoir I removed. They were tight on the new one I put in.

    Another place for you to look.

    See pictures HERE.
    Last edited by jase007; 10-26-2014 at 03:22 PM.
    Jason

    '90 325iX 5M, '00 528iT 5M Sport (mfg. 5/1999)
    BMW CCA member #130075
    JScott Racing

  5. #5
    Join Date
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    Update - I have done the following partition tests to find out the leak location:
    1. swap the red and blue gas line on top of the bag ---> sagging goes from left side to right side, indicating the leak is upstream (either at the connector next to the battery or in the clampshell)
    2. swap the red and blue gas line at the connectors next to the battery ---> sagging goes from left side to right side, indicating the leak is upstream (in the clampshell)
    3. swap the red and blue gas line on top of the solenoid --> sagging goes from left side to right side, indicating the leak is inside the solenoid.

    No my question is: can I buy this solenoid separately? Or can I rebuild this solenoid?
    solenoid photo.JPG
    schematics - 1.JPGSelf Leveling Suspension.png

  6. #6
    Join Date
    Jan 2016
    Location
    Houston, TX
    Posts
    1
    My Cars
    03 525it

    solenoid

    archyx,

    Nice test procedure! What did you discover about your solenoid? Repaired? Replaced?

    -Alec

  7. #7
    Join Date
    Jun 2005
    Location
    NorCal
    Posts
    168
    My Cars
    '02 525iT; '00 540i/6
    Old thread, but I'm having the same issue on my '02 525iT. Did you solve the solenoid issue? Repair, replace, or other solution?

    Quote Originally Posted by archyx View Post
    Update - I have done the following partition tests to find out the leak location:
    1. swap the red and blue gas line on top of the bag ---> sagging goes from left side to right side, indicating the leak is upstream (either at the connector next to the battery or in the clampshell)
    2. swap the red and blue gas line at the connectors next to the battery ---> sagging goes from left side to right side, indicating the leak is upstream (in the clampshell)
    3. swap the red and blue gas line on top of the solenoid --> sagging goes from left side to right side, indicating the leak is inside the solenoid.

    No my question is: can I buy this solenoid separately? Or can I rebuild this solenoid?
    solenoid photo.JPG
    schematics - 1.JPGSelf Leveling Suspension.png

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