BMW X5 E53 4.8is SELF LEVEL SUSPENSION

[Danny2121]

Hi,
I’ve recently changed all my 4 airbags for the Arnott type as previously the car was dropping front only over night and took about two weeks to go near enough flat bottom.
The previous bags were leaking as I did the spray bottle test.
Now I have the Arnott bags on it’s doing the same slightly.
My question is:

1 - Does the air compressor leak through the internal parts;
2 - Is it normal for the suspension to adjust the car level whilst parked on a hill at a slight slant;

The car lifts up and down ok with the 3 level switch, no errors.
When I get in the car and turn the key the car front end lifts up, is this normal or
Should the X never really do this unless there’s a leak in the compressor or underneath the right side of the car there’s accumulator etc…
If anyone can help would be highly appreciated

[andrewwynn]

You shouldn't notice sag. You likely have a slow leak in the piping or valves. You could find where with some diagnostic such as spray on the piping to look for joint leaks or if you can find the exaust tube you could put a balloon over to see if the outlet valve is leaking.

[Danny2121]

Thanks for reply!
Where would one find the outlet valve, I take it that’s at the compressor.
I were thinking of removing the panel under right under tray and spray leak detector over fittings etc….
It’s a good one as I thought by replacing the bags would have solved this.
They needed replacing as they were leaking, however there’s something else ��

[bcredliner]

I suggest doing the soapy water test again, including the air suspension bags, compressor lines and tubing. The bags could be defective out of the box. I always check my work first. It could be the compressor but if that is the case it often won't pump enough pressure to raise the vehicle to normal height. If the suspension is compressed at a wheel or wheels it will adjust to normal setting (within reason).

[andrewwynn]

The same seals that go bad and cause the compressor to over run could definitely also cause loss of pressure but that is upstream of the control valves I don't think that will cause a leak/sag issue. Should be a control valve leaking or some plumbing.

[Danny2121]

Thanks guys!
I’ll check new bags also.
I’ll keep a eye on it and if it’s dropping really bad I’ll have to take bottom panel off and spray all plumbing pipes/valves etc….
My thoughts are that I think you’ll get some deviation on suspension heights while parked on uneven and hills etc
If I had all 4 coils and parked on a uneven steepish hill the car would be down at the rear and different corners so on 🥴

Thanks again.
I’ll pan it out and report back!

[andrewwynn]

The system doesn't care about of the car is level: it compares how compressed each corner is and adjusts to make the car parallel to the ground.

[Danny2121]

Ok, are you saying that whatever hill or slight uneven surface I park on the X would adjust to be 709 rear and 707mm front?

[andrewwynn]

Basically correct, though it rounds to 1cm not 1mm precision.

The arms can get bent or out of alignment and the sensor can send an erroneous signal so real-time values from the sensors is important diagnostic

[Danny2121]

Thank you for your help Andrew ;-)