Maduro

Hey everyone, need some advice. I've gone through all the similar threads and read up on similar issues but still having a difficult time ascertaining the cause here.

2012 CLS550 (W218/C218) 4matic 77 000km/48000miles

After being parked or static for a short period (less than 48hrs) the rear of the vehicle sits right down.



Over the past year or so it would seem that I notice, if I catch the timing right, that the right rear ends up sitting lower first and then eventually the whole back end settles down:



I decided to look into this myself, got a set of jack stands and a new hyd. jack to get the wheels and wheel well liners off to have a look and see if anything was noticeable. Apart from the dirt/dust, I couldn't see anything obvious. All the bellows seemed intact and I sprayed soapy water on all the connections/fittings (at least the ones that I could see) and didn't notice any leaks:




















Next I found the location of the compressor and valve block in the rear drivers side and didn't find any leaks there after spraying some soapy water again:









So here are the facts:

• As mentioned rear end will lower right down after being static for a short period (seems like the passenger side first/lower)
• During driving everything seems normal (ie car will pump the rear back up and off I go) except, and I have only noticed this very few times, sometimes at higher speeds it feels like the back end is swaying almost as if I am going to lose traction/control.
• No CEL or any messages displayed
• At times, when parked/off, I do hear that momentary puff in the rear, which I believe is a normal sound caused by the relief valve in the block or compressor (don't know which one has a relief valve).

So what are your thoughts? Should I being eyeing that compressor and block as a culprit although they seem visibly ok or is it possibly an air bag (the rear passenger side since it seems lowest at times?). Am I correct in that the rear bags can be independently replaced of the strut where as the front ones are combined?

Thanks I appreciate your replies!

hyperion667

Sorry to say I do not have an answer for you, but your write up, description and pics are great, I'll certainly be paying attention to the replies of the mechanically inclined members, GL to ya!

Maduro

Thanks I decided to fill with pics because I had a very hard time finding anything relevant online for my model/year so if this thread ends up having a resolution in the end then maybe it can help others.

Ethric Kadey

So many photos, took a while to figure how to reply because I couldn’t scroll past that much text.

k I had this problem in the winter and when it got too cold it would freeze when it was lowered and not be able to rise.

I replaced both rear bellows. Everything has been fine since then. I too have been noticing my car dipping a bit again lately and I’ve been hearing the blow off go off when I get close sometimes. For now everything is working fine so I’m not gonna bother with it. If it happens again when it’s cold im
going back to shop to get them to fix it again for free.

if the car rises when you turn the ignition it’s ok. If it doesn’t rise after ignition you got problems and don’t drive.

cheers.

Maduro

It definitely does that but the fact that it lowers so quickly after being static (and some times unevenly) makes me think that the bellows/air bags might need replacing. Anyone know if you can do just one at a time or have to be done in sets?

Ethric Kadey

I would do it in sets if I were you. You could end up spending more money doing them one at a time. I’m in Canada and it cost me $2000 to replace two rear bellows.

cheers.

Maduro

I'm in Canada too, 1 local dealer, abhorrent quality of service and insane pricing. I plan to do them myself.

hyperion667

They know they're the only game in town and gouge people?? That's LAME! Sorry to hear that There are 4 dealers within a 60 mile radius of me and also several independent shops too!

Maduro

Reviving my own thread here. Just got the Arnott replacement air bags and am about to attempt the install myself.

Found some useful videos/guides on Youtube but am concerned about disconnecting the battery. This is done to stop the air system from making leveling adjustments while working on it but I was under the impression you shouldn't completely cut off the power supply to the vehicle, as it will cause other issues and resets.

Am I ok to do this or is there another way to turn off the air system?

Maduro

Replacement is complete. Interestingly, after several days being static, the rear of the vehicle will slowly hunker down again with the right rear being lower than the left (as shown above). So I still haven't solved the problem.

Is it possible a bad strut could be causing this VS a bad valve block? The car has 50k on it and the roads/potholes in this province are some of the most cringeworthy.

Raheel

Any further updates? Were you able to figure out the problem?

Maduro

Nothing to report yet, I haven't done any additional work. My plan is to replace the struts next at some point. I also just purchased a Launch Creeder Elite for MB and will be trying it first to diagnose the issue.

Maduro

An update, I purchased a 'Creader Elite' and got to playing with it today.

Recall that I had the right rear side lowering right down after being parked for about 24hrs, replaced the rear air bags with Arnott bags and still have the same issue.

The scanner tool is really neat. Very powerful, you can check everything and even actuate systems/parts of your vehicle (for instance I could release air from my suspension system, actuate the pump, increase/decrease pressure inside the struts themselves etc). Everything appears to be normal but the following error is the only thing showing after a full diagnostic/test with the Creader tool:



If I am to interpret that as the right front strut is actually bad and needs replacing, could it be the right front strut is the issue and the auto-leveling feature of the vehicle is trying to compensate for this strut and thus causing my right rear strut to continue to lower itself until it hits the stops?

Bulldog007

Interesting thread. I have the exact same make/model/year. Mine is also black. I think I have 85k on it now. The air shocks have always puffed or expelled whenever the car is turned off. It's obviously just a settling thing. Within a minute or two of turning off key you'll hear a POOSH! sound and that's it. As far as the rear end dropping down like that, I've experienced that but it's ONLY if the car sits for a week or longer in cold temperatures. Weirdly, in warm summer weather, the car can sit for weeks without dropping at all. The last time it happened I'd left the car in an airport parking garage for a very cold week while I went to Florida. When I got back the rear end was all the way down, but I started the car -dash said VEHICLE RISING- and then it was fine. I wonder if there is a way to pressure test the system with smoke. I'll be following your progress.

p.s. Could you provide some info on that diagnostic tool you bought? Or advise where you got it?

Maduro

This was always my normal experience with the vehicle but as you see in my pics, the rear right was lower then the rest of the vehicle.

As for the tool, it's a 'Launch Creader Elite' for MB and it's quite impressive.

https://amzn.to/40aifWw

This thing is bi-directional meaning you can actuate from the tool itself, for example, pressurizing/discharging your suspension system, running the pump, calibrating the actual ride height for the different modes ('Sport' vs 'Comfort') I wish I bought this thing a long time ago!

dee i

hey sir I had having the same problem you having just mine lowers on the rear driver side so I change out the air pump and air suspension valve block and then it still didn't solve the problem so the last thing I change was the air bags and that was the main problem the whole time me and the mechanic found out the the air bag is was was losing air when sit up come to find out from a mercedes dealer mechanic the the air bag have a shirt life span to be honest and he even told us it be best to just replace them with springs and I would never have that problem again ever...I may do that later down the line

Maduro

I decided to try the suggestion in this thread https://mbworld.org/forums/e-class-w...c-issue-2.html) and after parking in the garage (in 'comfort' mode), I disabled the Airmatic system by pulling 2 fuses and waited to see what happens. Low and behold, after about half a day, the rear right did sink about a 1/4" and the following morning it is now down 3/4" while the other remaining 3 struts seem to be holding in place.

Here is a summary so far:

• I've inspected the valve block with soapy solution and it appears ok
• I removed and inspected the air compressor incl. disassembling it and although the outside is very weathered the inside (piston and chamber) appeared very clean and it seems to function normal. I disconnected the main line and no moisture was present.
• I've replaced the rear air bags with Arnott bags (many threads seem to point to these being the most common culprit)
• I've ran some scans with the creader scanner, and vehicle level, sensors etc seem to be normal (voltages and readings) BUT I do have one stored 'abnormal' MSG stating that the Right Front level is out of tolerance and signal is below permissible value.
• I live in a harsh winter climate and a city with some of the worst potholes a vehicle can endure and have hit some real nasty one's in the past 10 years, but again, only have about 89 000KM on the vehicle.
• When swapping to my winter tires recently, the tire shop reported that my rear right tire was much more worn than the remaining tires.

So any suggestions of where to go from here? Is it possible that the rear right strut (no air mechanism in it) is damaged and slowly sagging causing me my headaches, or does the line itself to the air bag have a leak somewhere (incl. inside the valve block)?

KOAL1224

Hi,
I dont know if you have solved the issue since than,but i ve been experiencing the same problems as you. I have a CLS 350 CDI with AirMatic. Since i bought the car i ve been having a suspicion that something is not 100% with the suspension because the back end of the vehicle always drops down even after not using it for a few hours. Then as winter came one morning the rear driver side didnt raise up fully when i started the car,and is heavily tilting to that side. There is noting on the dash that would indicate a malfunction. However, when i push the ,,service mode" button to raise the car up to the max it is clearly raising the rear driver side as well,but not to the same hight as the other 3 corners. So with that i would think that the rear driver side suspensions is probably not blown as it is raising up a few centimeters.
Do you have any suggestion on it? What did you experience when you pushed the ,,service mode" button? Did your faulty suspension side raise up a few centimeters?

In the first 2 pics the car is in ,,service mode" and is clearly visible that it is higher,but the rear driver(left) is definitely lower than the other corners. Also,in this mode the car is still tilting to the left side.

Still in ,,service mode"

In the last 2 pics the suspension is in comfort and the rear left is a lot lower and is heavily tilting to that side.

Still in comfort mode.

W218er

Way late here... but I am needing to replace the air line passenger rear to the valve unit. Is the collet and fitting at valve block reusable? And where is the valve block on driver rear side; trunk or wheel well?

ChrisHimself

Are your level sensors ok?

W218er

Yes as far as I know. Had to trim quarter inch of hose and too short now

Maduro

It's located under trunk, rear drivers side corner, under a plastic covering. I would think that the collet/fitting is reusable (I've unscrewed/re-screwed them into valve block several times) but I've never removed a line itself from one yet.