AirMatic front collapse in Spot Mode only? Valve Solenoids need replacing?
 

Its a 2011 E550, which we owned since new. From day one we owned it, every once in a while the rear suspension would collapse overnight, then I would start the car and cycle through the modes (Spot > Comfort > Raised) a few times and then it would never happen again for like 6-9 months, at which point again I would cycle through the modes and it would be fine again for a long time.

About 2 years ago, the car stopped having issues on the rear bags all together, hasnt collaped in the rear in 2 years, BUT now the front is collapsing but only when I leave it in Sport mode. At first it started where if I left it in Sport mode there would maybe be a 10% chance it would lower, but now its gotten to the point where in sport mode its 100% chance that it lowers.

The really starange thing is that in Comfort mode it almost never does it, and in Raised mode I have left my car at the airport parkling for 2 weeks and the car did not lower. Infact in Raised mode the car has never lowered in the 6 years we've owned it.

I'm thinking its the solenoid valve body and not and issue with any of the bags, but then why would it only lower in Sport mode and not in others? I do have lowering links installed but the car is only very slightly lowered, maybe 0.4" lower than stock in each setting.

Any suggestions, greatly appreciated.

OK, to add more info. I sat in the garage with a beer last night to watch how long it takes for the car to lower. Put it in sport mode, turned the car off and locked it, here is what I noticed;

-The car fully lowers in Sport mode in the matter of 20-30 minutes.
-The car lowered completely evenly on both sides at the exact same progressive rate.
-When I put my fingers in the wheel well to feel how fast its lowering, I feel it get lower in "pulses", as in it lowers a fraction, stops, lowers a fraction. This applies to both sides.

I sprayed soapy water to wherever I could find a connection, shock towers, rear reservoir bottle, outside of distrubution valve, but I could not find air leak. I'm assuming that I need to find the vent tube for the distro valve and see if air is coming out of the to rule out damaged airstrut.

https://cimg6.ibsrv.net/gimg/www.mbw...22503ff320.jpg
Wohoo! Its not the front air bag / bellow that is leaking! So happy as unlike the W220 where you can find a complete re-manufactured strut assembly for $200, the W212 air strut is $1200 each!

I figgured that if it truely was the distribution solenoid valve that was leaking, the air has to be coming out of the fresh air dump tube. So I took the line off the filter, which is easily accessible under the car and plugged the end of the dump tube with a 3/8" socket extension. Low and behold the car stayed at the exact height for the last 2 hours! As soon as I took the plug out, there was a big woosh of air, and while the car didnt immediately drop, it again started to slowly creap down in the front.

So I'm about to order a new solenoid valve since its only $238 new form Mercedes. If that doesnt fix it then its the pump as it seems like its the pump the controls the dumping of excess air and not the solenoid. Even if I have to replace both the solenoid and pump, thats still less than half of what just one air strut costs. We shall see. Keep you updated.

I'm not really affraid of the Airmatic system as its actually quite simple. Its really only 3 parts, the airbags, the air pump and the distro valve/solenoid, so the failure points should be easily traceable.

My W210 wagon has the hydro-pneumatic self-leveling system in the rear, and I remember people not familiary with it complaining on how complicated and expensive it was to maintain. This was merely a misconception from the SLS systems of BMW's of the 90's. The Mercedes system was dead reliable. My w210 wagon currently has a quarter million miles on it, still original SLS system that works perfectly. You can't get that kind of longevity out of a rear shock absorber.

I replaced my air ride solenoid valve block about a month ago. It was one of the last parts of a long line of items I ended up swapping out due to malfunction of airmatic. I did the air compressor, next both rear bags, next the solenoid valve block, then replaced the airmatic air filter (due to suggestion from forum member) and lastly I had to replace the airmatic hoses/lines. Until I replaced all of the items, I was getting a malfunction and/or my car would be slammed down the next morning.

Just an FYI I replaced a front suspension last year at the dealership and that alone cost me $1900. All the above mentioned pieces I've recently replaced came to about $2,200 with me buying all the parts and shipping to an Indy and paying them for labor.

I have a 2010 E550 with the same issue. I currently have it raised on stands and am about to swap the front and rear air lines at the solenoid, just under the left rear bumper. All 4 wheels have to be off the ground, etc and when I put it back down I need only wait until tomorrow. If the front still lowers to the tire then it is the front air bags. If the rear is the side to squat, that rules out replacing a 800 dollar shock and it's much cheaper fix.

I had the exact same thing happen with my 2010 E550 and it was confusing how it went down only in sport mode or that’s what it seemed.

What really happened is that the left side air strut had a leak. If I left the car in sport mode it was down all the way in the morning and if I left it in comfort it was lower but not all the way down. Reason for it not go all the way down in comfort mode is that the one air strut has enough stroke in higher position to generate enough pressure as car lowers to hold the car up from going all the way down.

You have a leak in one of the front air struts. Change both out.