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Discussion Starter #1
35d, E70, MY2011, June 2010 build, odometer ~142,000 miles.

Without any warning, but the night did get unusually cold, both sides dropped - driver side a bit more than the passenger side.

There were no warning signs or fault codes . . . would have guessed some level control malfunction message, none showed up.

Given the age of the car, I was expecting this . . . but what surprised me was both sides going down during the same night with no prior warning.

Always assumed the plumbing for both sides were separate - i.e. the left and right airbags are in parallel and NOT in series - why - many have reported only one side going down . . . and both going down on the same night seemed too much of a coincidence.

Thinking logically, I thought it must be a leak further upstream. Before spending any money, asked my Indy to do a soapy-water check - he found leaks on both airbags!

In all the nearly nine years I have had this car, I have never heard that compressor running - unless it came on while the car was being driven. BTW for those (like me) who have never heard this compressor running - it pretty loud and gets switched on when you open the driver door.

I am posting this note to capture all the information I gathered trying to sort this out.

A HUGE shout out to a few "very regular" contributors to the E70 forum - you folks gave me some REALLY good pointers and some exceedingly valuable links - will include them below. THANKS!

  • Replaced both air bags - went with Arnot replacement airbags, Indy felt they were better than dealer supplied ones.
    Interesting outcome - the rattle around the middle row seat (the only rattle after nine years and 142,000 miles!) occurs at precisely 1,640 rpm has now completely disappeared!​
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  • Although the compressor does not switch on anymore I am noticing a slight height variation . . . when measured in the morning (cold) there is about a quarter inch variation between driver and passenger side. The variation on the same side between cold and hot (after driving the car) is about an eighth to a quarter inch max. Not sure if this is normal as I wasn't watching this before the airbag leak.
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  • Is there a way to tell if the compressor is running when driving the car? I don't think Carly/OBD2 port monitors this compressor.
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  • Contrary to RealOEM parts diagram, you can get the solenoid valve block by itself - here is the Arnott Solenoid Valve Block that fits my car.
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  • Here is, somewhat dated, one of many discussions about this issue.
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  • Here is the wiring diagram for the electronic ride height control
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  • For the highly skilled DIY person, this post might be useful.
I am not fully convinced this issue is completely solved . . . the quarter-inch ride height variation somewhat bothers me . . . since I don't have a reference point, I can't be sure this is normal or an issue.
 

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I have the 2011 35i and when it gets real cold my drivers side rear drops all the way down as well.....i just give it time to raise back up before moving and so far i have not seen any negative issues with allowing this to happen. when it stays above 50 degrees it seems to stay level though...
 

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Glad you got it figured out and thanks for posting everything in one new post. subscribing.
 

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Discussion Starter #4
Update . . . so far the problem (sagging rear suspension) appears to be sorted out . . . replaced both rear suspension airbags (which showed leaks - used soapy water to detect it) . . .

In this instance logic failed me . . . I didn't think both airbags would go out the same night . . . but it looks like that is exactly what happened.

I have now been measuring the body height from the ground for several weeks . . . cannot detect any sagging even after parking the car for a few days in the garage.

Interestingly there is about a quarter inch difference in height between driver and passenger sides - passenger side sits about a quarter inch higher than the driver side . . . impossible to see it without measuring it . . . since I don't know if this difference was there when the car was new, for now I am going to ignore it.
 
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