No Dash warning, but rear end sags?!?! Please help

[nlcurtis]

I have an 04 4.4 X5 with rear sport self leveling suspension. The back end of course is sagging real low.

I have checked all corresponding fuses in the glove box and in the rear.

I have made sure the bags, resoviors, and lines are not leaking with soapy water the best I can

I removed both rear tires and angled the sensors as if it were high or low with car on but not started

I even went crazy and took off the relay at the pump and jumped two pins, which the compressor came on, BUT as soon as I disconnect the "jump", I hear a lingering hiss within or around the compressor and it sounds every so slightly that the hissing may even be occurring when it is on. I checked and tightened all hoses connected and still the rear does not rise. Please help me!

[David.X5]

Sounds like you have a leak at the compressor

[nlcurtis]

That's what I was afraid of. New compressor or conversion kit is now the question. Would you suggest a rebuild or a conversion kit?

[g300d]

^this.

Going off what you said, I would look for the source of that hiss first.

[David.X5]

Could be something simple. Try to figure out why the compressor is leaking. There are some repair kits available. Might just be a plastic hose leaking at the compressor.

The conversion question is a personal thing. I like having the air suspension. Some people prefer getting rid of it... While indefinite life would be nice, I am not going to complain about 15 year old parts needing maintenance/repair.

[nlcurtis]

I'd rather keep them as well, but for a new pump it would be a burn to the pocket.

I will take apart the pump and if possible leave air in the system to not completely deflate the bags. ( I let out some air moving from the bags and up to make sure there was air and that how I got to the pump as well)

Does anyone have a diagram of the compressor? I loosened each hose I could enough to hear air come out. So there is still air being held, but not allowing to put through to the bags? Somewhere on the forums I read that the compressor has a sort of "walls" or chambers that open and close to allow air to escape or trap to put into bags. Anyone else read this or know anything about it?

[David.X5]

This guy sells a seal kit that seems well liked here. He has a link to a video on who to rebuild the pump - should get you started - BMW x5 E53 5 Series E39 Wabco Air Suspension Compressor Pump Repair Refurb Kit | eBay

[nlcurtis]

Awesome, thanks David.X5.
Thank you all for taking time out of your day.

[nlcurtis]

So, after testing the compressor out a few more time. I have concluded that the air is being compressed from the compressor but the solenoids that connect to the two hoses to both bags is not letting the air out almost as if it is blocking the air from continuing past it to the bags. When I took off the pressure it was from the air that was built up within the compressor that's not being bypassed through the solenoids. The air hissing from around or within the compressor is more than likely due to the air thats being compressed from the compressor not being by passed through the solenoids to the bags so its just built up air that has being in escaping elsewhere. Does this sound right?

[David.X5]

Here's a diagram if you haven't found one. I don't know what to suggest next. If you are sure the pump is working as you describe, then perhaps it is the module. Several people have had modules fail. Can't recall anyone complaining about valves failing, but I guess that might also be a possibility.

If the part numbers match, there are some used modules on ebay for $80-$90. Still cheaper than getting dealer diagnosis.

I wouldn't pay $500-$600 for a new module without better diagnosis, though.