Air suspension issue. Help please.

[Amebb]

Hi there
I have a x5 with rear air suspension issues. The front suspension has coils and not air suspension.

So, about 6 weeks ago I replaced the rear air suspension bags at the rear. From then I have been having issues with the suspension.
I used INPa to pump up the rear suspension. The air bags stay up for a about a week and then go down slowly. OR.... if I am driving on the motorway doing 60 mph plus the rear suspension drops within 10 minutes or so.

I have replaced the air compressor at the back. I have checked for leaks using soapy water etc.

Can anyone tell me what else the issue could be or where i need to look at to fix the issue?

Thank you.

[X5Sport]

Is the ride height sensor OK?

You can see it looking at the underneath of the car from the back. It's located on the lower suspension arm- a little black cube, (size around 50mm each side). It will have a plug and a little arm, with a tiny ball and socket each end.

IMG_2726.jpeg (99.4 KiB) Viewed 1421 times

[Alan Gunn]

Also did you use the new "O" rings.
Some don't change them and get this problem.

[henrym3]

The pipe on either side which connects between the bag and accumulator may not be seated properly. I know you checked for leaks but if it can stay up for a week you may have checked during the time it’s behaving itself.

[X5-D-Sport]

i learned of a handy little trick....

Solved with some silicone spray in a can..
Under the spare wheel lives the compressor & valve block... .. disconnect the battery & cover the terminals with a rag or wooden board to prevent any short circuits ...open up the circular case that contains the valve block & pump

in the valve block there are 3 solenoid valves with rubber seats...
I understand that after many thousands of miles, these will have has thousands of litres of air going thru them raising & lowering the suspension to suit loads & driving etc... and the unit will ingest an amount of dust & dirt

I disconnected the vehicle battery, released/eased the couplings in the front Right of the spare tyre well on Blue & red couplings so as to release some air & allow the suspension to sink 6 inches.
The re-tighten the air couplings - NOTE, they only need nipping up finger tight to stop the air hiss to re-seal, as they are only plastic and will break easily...

THEN...

So, there is a single pipe that comes from the air pump to the valve block.
Undo at the pump end, & squirt a good several second squirt into where the single pipe connects & re-connect the pipe.
Disconnect the other end of the pipe at the valve block & put a good squirt of silicone spray in there also, & reconnect the pipe.

If you are good with mechanics & confident, you could also strip the pump & lube the piston with a good drenching of silicon spray & a good squirt into the cylinder head before re-assembly.

This compressor only has a flap valve, so there is no risk of a hydraulic lock in the pump.
You will notice that the pump is bone dry internally & get very hot due to this when running.

Now re-assemble the whole lot, & reconnect the battery, & it is most likely that the sagging suspension issue will cease.

Hope this helps.

regards
Grant B