XSeries-forum

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.

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.

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

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.

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