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Thread: self levelling gone bonkers

  1. #1
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    self levelling gone bonkers

    Hello all.

    Last year I parked my car normally (530i 01 E39 Touring ) and the back end rose about ten inches. I scratched my head a bit and used the other car. Then two days later it returned to normal - Last week the back end dropped five inches. A very uncomfortable ride but luckily I was only a few miles from home.

    It has been two weeks and it hasn't chosen to rise. It has stayed low, although the pump does run for two minutes when I open the tailgate. I'm unsure how to check if it is a faulty bypass valve, compressor leak, failed seals, or control module. (which seem like the likely options to me.)

    What do i do next? Does anyone know how the valves are controlled and what voltages are expected where.

    Throwing money at it is not a favoured solution.


    thanks in advance.
    Neil

  2. #2
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    I would start with checking the rear ride height sensor. Located by the link on the rear lower contol arm. The link could come off or the ride height switch could be bad. Its a simple rheostat so check with a ohm meter for smooth operation.

  3. #3
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    I had this exact same issue , my wiring to the sensor had been previously replaced / soldered , so I cut it out and re-soldered it and it was all good .
    Wiring is under the boot floor section

  4. #4
    geargrinder's Avatar
    geargrinder is offline Having No Trouble Here BMW CCA Member
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    Agreed for either physical / mechanical or wiring issue on the ride height sensors. One on each side. Not too complicated to give a basic diagnose.
    2003 M3CicM6 TiAg
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  5. #5
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    Finally got round to looking at the suspension, I'm not a keen bean.
    Thanks for your suggestions. And it is good to have somewhere to unload.

    I've inspected the wiring and it looks okay, no visible wear or anything obvious.
    Currently the sls light warning light is lit

    Car very low _____________________pump runs every few hours, suspension does not inflate

    Open the tailgate. ________________ pump runs, suspension does not inflate

    Propped the car up on the towbar.
    Both rear wheels hanging with fully extended suspension.
    tailgate open or closed
    Jack up the right rear wheel ________ pump runs, suspension does not inflate

    Propped the car up on the towbar.
    Both rear wheels hanging with fully extended suspension.
    tailgate open or closed
    Jack up the left rear wheel _________ pump does not run

    If I disconnect an air pipe it produces big bubbles when the pump runs and the end is held under the surface of a cup of tea.

    How do you identify a failed pressure relief valve?
    How do you work out if the pump is producing sufficient pressure?

    Not forgetting that the car was fine and then dropped. Surely the electronic controller or the air valve that lets air out has to be my problem?

    I'm tempted to buy
    a replacement pump...
    or a pump seal kit
    and a controller
    and a hall effect sensor gizmo and it will be annoying because three of them are not needed.

    Inspecting the left hand wiring again...

    Wagons'ho
    Where do you check sensor ohmage, at the controller?
    and what sort of numbers would I be looking for?
    Last edited by mustapha mondeo; 06-19-2017 at 02:05 PM.

  6. #6
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    Quote Originally Posted by mustapha mondeo View Post
    ...

    If I disconnect an air pipe it produces big bubbles when the pump runs and the end is held under the surface of a cup of tea. ...
    I have been fighting with mine for 7 months and finally got it all working as it should. So I have done a lot of testing and waiting and testing and waiting and really know exactly how this all works.

    There really is only 7 components in the entire system
    1. pump
    2. air solenoid pack - 1 solenooid for each side to level car with out over extending one side. only availalbe as a single unit as they are molded together.
    3. hoses
    4. air bags
    5. accumulators
    6. control box - controls turn on/off of pump and actuation of the air solenoids

    So I have a question about your above statement. Where are you disconnecting the tube from to put it in the cup of tea? at the top of the air bags or at the connection block in the spare tire well?

    with an answer to that question i can start helping you to figure this all out and what parts may need to be replaced.

    Also I have made up a test to see if the pump is working and pressurizing properly using two pressure gauges and push on hose adapters. parts are from Amazon. My links are for USA but you should be able to find something in the UK very similar.

    https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

    https://smile.amazon.com/MettleAir-M...+to+female+npt


    And if you have to purchase a pump or solenoid the least expensive place I have found is AEROSUS.com
    Last edited by schatzy62; 06-19-2017 at 03:35 PM.
    2003 525iT Automatic, Topas Blue Exterior, Gray Leather Interior, Sports Suspension, Sports Seats, M 3 spoke Steering Wheel.
    2008 328xi E91 (wagon) Automatic, Barberatot Metallic Exterior, Terracotta Leather Interior.

  7. #7
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    thank you for your response. And thanks for the links.

    I disconnected the air tube on top of the right rear airbag connector where the tubes are going through a grommet in the boot floor. Not the block.

    I like the idea of a pressure test gauge. It would be good to know if the solenoids are at fault.

  8. #8
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    Okay here we go.


    Here is a diagram of the system and all the parts.


    E39-Touring-Air-Susp-Diagram.jpg


    From what you have told us previously we know the following:


    1. pump runs
    2. pump turns on and off
    3. Level sensors seem to be working (with car off ground pump does not run and when a wheel is lifted pump turns on i.e. the level switches are working)
    4. pump is producing air at the right airbag connector (you removed line and it makes bubbles in a cup of tea)
    5. car is not rising when compressor is on.


    To start testing we need the following:


    1. two pressure gauges
    2. two 4mm push to connect adapters for the pressure gauges.


    For the testing.


    1. lift rear of car and support with jack stand
    2. disconnect airlines at top of airbags/accumulators
    3. carefully remove ferrel (brass ring inside nut) and nut from air line
    4. push on the gauge/adapter on each air line
    5. turn key to on position
    6. lift right wheel - pump should turn on and pressure gauge for that side should go up to a max of 165 - 195 PSI (11.4 - 13.5 bar) it it should turn off automatically.
    7. lower wheel - pressure gauges (when I tested this) evened out and dropped to about 50 PSI (3.4 bar) each. (not sure why this happens but that happened each of the 8 times I tested this)
    8. repeat lifting left wheel - should have same results.


    If one or the other sides or both do not pressurize to at least 150 PSI (10.34 bar) when the pump is running then you certainly have a leak somewhere.


    Post back the results of this testing and we can go from there.

    FYI


    If both sides pressurize to at least 150 PSI (10.34 bar) then I would suspect that you have a very leaky air bags or bad reservoirs (rare).


    If one side or both do not pressurize then your leak is somewhere in the lines, solenoids or pump.
    Last edited by schatzy62; 06-20-2017 at 09:39 PM.
    2003 525iT Automatic, Topas Blue Exterior, Gray Leather Interior, Sports Suspension, Sports Seats, M 3 spoke Steering Wheel.
    2008 328xi E91 (wagon) Automatic, Barberatot Metallic Exterior, Terracotta Leather Interior.

  9. #9
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    One other note. I miss read this earlier after re-reading I have some other comments.

    Quote Originally Posted by mustapha mondeo View Post
    ...

    Propped the car up on the towbar.
    Both rear wheels hanging with fully extended suspension.
    tailgate open or closed
    Jack up the right rear wheel ________ pump runs, suspension does not inflate
    With this statement if there is not a leak in the solenoid, lines and pump then the right side should rise even if the left does not.


    Quote Originally Posted by mustapha mondeo View Post
    ...Propped the car up on the towbar.
    Both rear wheels hanging with fully extended suspension.
    tailgate open or closed
    Jack up the left rear wheel _________ pump does not run
    From this there is definitely something not right with the left side. Possible causes:
    1. bad height switch - this would not affect the right side though
    2. bad solenoid - if this was the problem then it could cause the right side to not rise
    3. bad controller - this would most likely not cause the problems with the right side though.

    Have you unbolted the pump housing and inspected the pump for physical damage like a part explosion?

    I am leaning toward either the Solenoids being bad, or the pump not pressurizing for both sides to not rise up.

    The pressure relief valve is part of the pump and can not be purchased separately. This can be tested by putting one of the gauges on the output of the pump after disconnecting it from the Solenoids.
    2003 525iT Automatic, Topas Blue Exterior, Gray Leather Interior, Sports Suspension, Sports Seats, M 3 spoke Steering Wheel.
    2008 328xi E91 (wagon) Automatic, Barberatot Metallic Exterior, Terracotta Leather Interior.

  10. #10
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    I had looked at that diagram online but moved on thinking it was not helpful.
    But having spent a bit more time considering the conundrum its going to be useful.
    By the time iv'e finished with it I reckon I'll be able to get the pump to play a little tune.

    Sorting out a methodical approach is half the battle.

    thanks for your help. I'll be back....

  11. #11
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    Irish, English breakfast or orange pekoe? The tea.

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  12. #12
    geargrinder's Avatar
    geargrinder is offline Having No Trouble Here BMW CCA Member
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  13. #13
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    Quote Originally Posted by geargrinder View Post
    Earl Grey.
    +1
    2003 525iT Automatic, Topas Blue Exterior, Gray Leather Interior, Sports Suspension, Sports Seats, M 3 spoke Steering Wheel.
    2008 328xi E91 (wagon) Automatic, Barberatot Metallic Exterior, Terracotta Leather Interior.

  14. #14
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    ... finally. I found a pin hole in the nearside accumulator. Smeared it in epoxy resin. Cable tied a penny against the blob. The suspension is now working. What I actually needed was someone with unimpaired hearing to tell me about the quiet hissing noise. If I had turned my hearing aids up earlier... I now have a much deeper understanding of air suspension and its parts and are now waiting for it to do the crazy reach for the sky again. When I will buy some coil springs.

    Thanks to everyone who commented.

    I'll be back.
    Last edited by mustapha mondeo; 08-09-2017 at 04:10 PM.

  15. #15
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    Glad to hear that you did find a real problem. I know i thought I was voing crazy tring to find my issue. I will keep my fingers crossed that you have no more problems.
    2003 525iT Automatic, Topas Blue Exterior, Gray Leather Interior, Sports Suspension, Sports Seats, M 3 spoke Steering Wheel.
    2008 328xi E91 (wagon) Automatic, Barberatot Metallic Exterior, Terracotta Leather Interior.

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