Rear air suspension dilemma

[eckbmw]

Hope anyone on here can advise.
The last 3 mornings my E53 (Air suspension on rear only) has been sitting extremely low and arches almost sitting on tyres.

I have no error message on OBC such as "self lev susp inact" and indeed no errors showing on INPA.

Fortunately I have a copy of INPA on an old laptop.

Each morning I have used INPA to raise the car succesfully and have noticed when hitting key to raise rear end nothing happens, fortunately INPA gives the option of raising both the left and right on their own and this has the desired effect (it's worth noting that at this point I have disabled transport mode).

I thereafter drive the car around town most of the day without any issues but come the next morning there it is again sitting hunched down.

Surely if there was an air leak this would manifest itself quickly and be noticable within a short space of time.

Could it be the linkage on the sensors?

[williamx5]

Good day!!

First, I would suggest you include the vehicles you have in the signature area so we all know what you are working with, and you never have to worry about including that in the posting again..

Oddly, I don't think the year or motor size makes much difference here... If you have an alarm, the controller won't do anything until that alarm is deactivated... You may need to toggle between the different modes, then into normal again... This should clear the alarm... If you have a message of inop, the air suspension won't do anything...

I have 2-axle air in my 2004 and it had an issue... I went to coils until I figured things out... Since you only have rear air, you could just get a pair of rear 3.0L coils and never need to deal with the air ride again... Only recommended if you will never tow anything heavy...

Cheers!!!

[Emory39]

eckbmw, You could have a small leak/ but whats odd is that is on both rear suspensions. Once when I was working on a problem just like this I had most of the air lines exposed and I spray them with soapy water. what was leaking was the valve unit. number 1 in the diagram RealOEM.com - Online BMW Parts Catalog that is located about in the middle of the X on the right side underneath the plastic covers. That valve separates front from rear air supply.

hope it helps. do test it before jumping the gun and buying a new one.

[Gregory891]

I also fully endorse keeping the rear only air suspension (which I have). It's strange that it's not throwing a code and the light on the dash. There are only 3-4 key things that go bad, in order of occurrence:

leaks in the air spring / bladder (one per corner, buy from Arnott)
height sensor error (one per corner, use genuine BMW)
air line leak
accumulator leak (one per corner)
air compressor issue (which most of the time is the seal - you but a replacement one from a guy on Ebay in the UK)

If you have the original air springs, you're fortunate to have gotten this far. While its less likely that both would have a significant leak at the same time - this is a wear item and they are rather easy to replace.

The soapy water trick is a good thing to try, both in the exposed areas near the air springs and lines AND then inside the car by removing panels.