One last thing, your compressor runs whenever it needs to correct the ride height of your vehicle. For example, if you load up the whole family and the kitchen sink, the compressor adds air to compensate for the extra weight. When you all climb out the vehicle will obviously raise up which activates the solenoid in the valve block and air is expelled, bringing the vehicle back to a level setting. This all typically happens every day without most of us even noticing.
And by the way, I replaced both rear air springs (Arnotts are the only way to go) and my compressor is still in tip top condition. I stripped it and the valve block to check because that's just in my nature but ultimately wasted 2 hours of my life I'll never get back. It really is a pretty simple 12v air compressor albeit of the high duty cycle variety.

Thanks guys. By now I read many posts about symptoms and DIYs of rear self-leveling suspension. Now I'm clear that's the issue.

Like I mentioned earlier, it only happens once in a few weeks, and I can't tell by eyes that my car rear is lowered or having uneven heights between left and right, before I open the door to see it does inflation.
Or my car's air springs only leaks in a very small degree?

I do prefer the preventative fixes, but I doubt the behavior of the car will still be the same after I replace the air springs...

ART-qitec, after you replaced the parts, do you no longer hear that loud compression noise anymore?

Yes the car was silent after that. I agree with Mart_dev in that a lot of compressors do sound that way but I've spoken with numerous BMW mechanics about it and they all say that the compressor in our cars shouldn't be audible...in fact they say the compressor starts making that sound when it's starting to go out. But like Mart_dev said, don't throw parts at the car first...just see a mechanic as soon as possible, when my compressor went out the car was extremely dangerous to drive. It would almost lose control every time I drove over a pothole.

Also if it is in fact your compressor, the sound would be coming from under the bottom of your car right below the passenger side door. Best of luck to you, let me know if you have any other questions.

I used to have EXACT same noise (including the airy "whoosh" at the end) for several seconds regularly after a drive. Since the vehicle was new.

Always wondered what it was, and even brought it up to the SA. She told me it's something to do with emisions. I am pretty sure it was just a dumb answer to get me off her back.

I am not sure it's a suspension compressor though..

Oh, I too have the one at the end, but it's different from the one that occurs when I wake the car up. The one at the end is the system that pumps fuel vapors so they can be pumped into the engine and burned when the engine is running again.

I do notice there are different kinds of sound, every time after driving and parked car, but I have to be close to the car and listen intentionally. I thought that's maybe from some mechanic, or some pumps, to finish the things up. So this matches what ART-qitec said about 'spoken with numerous BMW mechanics about sound shouldn't be audible' and what mart_dev mentioned compressor is acting everyday.


My air springs are not leaking too fast to drug the compressor to death too soon, so I guess I can wait for Xmas time to see if Arnotts would be on sale :)

Well, thank you for answering my question then! :)

fyi never take your vehicle to BMW OF MANHATTAN there are theft they will take parts from your vehicle and replace other people bad parts
oil was leaking from valve cover,i take it to bmw of Manhattan for replace, i endup with multiple problem like check engine light and coolants leaking. when i take it back they reset the fault which is evap,3 day after the chk light came back on when i scan it ssme evap i take it back ,they told me thst the purge valve bad,they replace it.3 day after the light came back on when i scan it ,the same evap i take it back and also told them about the coolants leak again they reset the evap code and told me thst my water pump is leaking,i had replace the waterpump before i take it in and notice that the hose us leaking but they insisted that the pump is leaking,i went and take my vehicle back since then the chk light on same evap and water pump will run every time i unlock the vehicle and will run when turn off the engine every time it run it will run for about 10-15 min now wnen it run it will kill the battery if any got the answer what cause the wter pump to run when i open the door i will greatly appreciate. thank you

1. BMW of Manhattan is notorious, even legendarily, bad.

2. How do you know the WATER pump is running??????

3. Did you know this thread is 4 years old?

Welcome!

i can see the coolant circulating in the expansion tank, is there a fix for this its a 2012 bmw x5