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The common airmatic issue update

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E-Class (W212) 2010 - 2016: E 350, E 550

The common airmatic issue update

 
Old 03-30-2018, 02:34 PM
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The common airmatic issue update

Here's an update for what has happened so far. When the temperature outside would get cold and after approx 4 to 6 hrs with the car sitting there, the right rear suspension would drop (tire tucked under the fender). It would level out though once I turn on the car. Sometimes indicating to allow the car time to rise up and level out. Testing the air system (priming it, pressurizing) and looking for leaks didn't show anything noticeable, but what was noticed was the right rear level sensor would not respond when simulating it with functional test Got the right rear level sensor replaced. Also noticed the left rear level sensor was apparently the incorrrect one and that one was replaced too. The car still decides to lower the right rear suspension when parked and off and it looks like the problem still isn't solved. What makes it more confusing is that when changing the ride height of the vehicle (the button on the center console) to higher, the problem would go away. Even in cold weather and the car sitting there overnight you wouldn't of known that it has this issue. Only when its on its normal height does it do this. So now im wondering what else could it possibly be. I was advised that the right rear airmatic bag be changed but I'm 99% convinced its not a leak. Has anyone else resolved this sort of issue? I don't mind the keeping the car raised but to me that's more of a bandaid fix then solving the actual problem. Any advice would help and thanks. Happy Easter everyone!

Last edited by ChildishBenzino; 03-30-2018 at 02:56 PM.
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Old 03-30-2018, 03:31 PM
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In my case , about 2 years ago , my rear drivers side would drop during winter , and after trying to figure out was wrong , did a lot of searches , and everything pointed to the air bag.
replaced it with arnott , and no more dropping ever since. So if you havent replaced that air bag yet , u probably would wanna start with that.
those micro cracks in rubber seal on the bottom of the bag are invisible , but when it gets colder it shrinks (or however u would explain this) and leak air.
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Old 03-30-2018, 05:53 PM
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Originally Posted by ChildishBenzino View Post
What makes it more confusing is that when changing the ride height of the vehicle (the button on the center console) to higher, the problem would go away.
When you say 'higher', do you mean at its highest level or are you referring to the 'comfort' mode setting (as opposed 'sport' mode). You can raise the car even higher than 'comfort' mode.
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Old 03-30-2018, 06:05 PM
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Originally Posted by - Mover - View Post
When you say 'higher', do you mean at its highest level or are you referring to the 'comfort' mode setting (as opposed 'sport' mode). You can raise the car even higher than 'comfort' mode.
Its on comfort mode. I rarely change it to sport mode. Been keeping that raised car button on which has been solving the right rear suspension sagging when parked
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Old 04-02-2018, 03:10 PM
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Sounds like the exact issue I had, If the car stays level in raised mode, and stays up for days on end, its most likely not an air leak from the airbags, but instead the air distribution solenoid valve not shutting correct for that one particular side.

https://mbworld.org/forums/e-class-w...replacing.html
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Old 05-03-2018, 10:07 AM
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Originally Posted by Ungarisch View Post
Sounds like the exact issue I had, If the car stays level in raised mode, and stays up for days on end, its most likely not an air leak from the airbags, but instead the air distribution solenoid valve not shutting correct for that one particular side.

https://mbworld.org/forums/e-class-w...replacing.html
This is whats happening with mine. On 'sport' mode, the front will drop 5cm (2 inches) over night. This happens consistently.

On the highest raised mode, the front will drop 1 cm(1/2 inch) overnight consistently.

You would think if there is a leak, the car would behave the same irregardless of the height setting.
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Old 05-03-2018, 12:41 PM
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Originally Posted by - Mover - View Post
This is whats happening with mine. On 'sport' mode, the front will drop 5cm (2 inches) over night. This happens consistently.

On the highest raised mode, the front will drop 1 cm(1/2 inch) overnight consistently.

You would think if there is a leak, the car would behave the same irregardless of the height setting.
mine drops to the ground in the front in sport mode, in raised mode it stays relatively the same. But I'm in SoCal where there is very little temperature change between day and night. There is some drop that is normal and expected in colder climates as the air in the bags compresses for the cool air. 2" is not normal through.

I do want to point out, and I'll update my thread as well, that it turned out to not be the air distribution solenoid, but rather the fresh air vent intake/valve that is built into the pump itself. Its the thing that makes the "pssss" sound once your car levels. While Mercedes doesnt sell this part along and will tell you to replace the pump, Wabco does sell it, its a $49 part that you can replace on the pump itself.
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Old 05-04-2018, 08:36 AM
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On 'comfort' mode, the front of the car didn't drop overnight either.

I'll keep trying a different mode each night to see if its just 'sport' mode that is having the issue.

How did you come to the conclusion that its the solenoid in the compressor ?

One thing I should do is put a scanner on it to see if the airmatic system has thrown any codes.
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Old 05-04-2018, 01:19 PM
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The truth is that I don't 100% know if it's the pump solenoid. My new pump is still in the mail. The thing that I do know for sure know is that the air is escaping from the vent tube, and that there is no leaks on the lines, fitting or struts. I don't have a MB SDS tool, so I cant diagnose it much further than what I have already done.

Logic would dictate that the front is lowering because that is the heaviest part of the car. My car lowers completely even on both sides, at the same time, same rate, which might have been a clue that it wasn't going to be the distribution valve as that would have caused individual corners to drop at different rate, unless coincidentally both front solenoids were leaking at the same time and same rate.

Since the air is escaping from the vent tube, as far as my understanding goes it really could only be one of the following things. Distribution solenoid valve leak (which for me it turned out not to be), pump intake exhaust valve solenoid leak, level sensor reading error, or software glitch. Unlike the W211, which has individual valves on the shock towers as well, the W212 does not seem to have it, or if it does then its built into the shock.

That part that makes me lean towards a sticky solenoid is that it's very intermittent, but also mostly temperature related. My car stay up just fine in Comfort mode during the day, but overnight it lowers, which I attribute to temperature change, so I'm hoping this rules out software glitch. Plus if it was software, more cars would have this issue. Also, if it was a false reading from the level control sensor thinking the car is too high, then the car would lower faster than over the course of 30 minutes it is now and it would be per side, not both evenly, so I'm ruling that out as well for now.

So that leaves the solenoid that switches the pump from intake to exhaust, I'm thinking that its not fully closing the circuit. As to why this only happens in sport and comfort but never in raised, well that I dont have a clear answer for. Maybe the greater bag pressure in raised mode helps seal the valve, just a guess..

EDIT: I've been tossing around a lot non-MB approved technical lingo. The intake/exhaust solenoid that I've been referring to in my previous reply's is actually called the "AIRmatic pressure reduction valve", sometimes called the pressure relief valve.

Last edited by Ungarisch; 05-05-2018 at 12:13 AM.
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Old 05-05-2018, 11:00 AM
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Originally Posted by - Mover - View Post
On 'comfort' mode, the front of the car didn't drop overnight either.
I'll keep trying a different mode each night to see if its just 'sport' mode that is having the issue.
This problem is definitely related to the mode chosen.

Actually, its not related to the mode after observing some more. It just takes a lot longer for the car to start to drop, even when its in 'comfort' mode.
Last night, I had I parked the car in 'sport' mode. After having it sit for 2.5-3 hrs, I went to the garage and sat in there for over 30 minutes and observed the following.

1) I couldn't hear any air escaping from anywhere throughout the entire time.
2) It seems that the lower it drops, the rate at which it drops gets faster like a building or tree toppling over.
3) I could hear some kind of clicking sound (like when hot water goes thru copper pipes) every so often 3-10 minutes around the front of the car. This may have been the engine continuing to cool.
4) Opening the door electronically with the key caused the front to raise again rather quickly using the air in the reserve tank. I could hear the valves and movement of air.

Could someone confirm that the airmatic system doesn't try doing height adjustments when the car is sitting there off after 10-15 minutes ?
I know that it still has power, similar to how your windows do after shutting the car off a certain period of time. But just like the windows, is the airmatic system in a resting state with no power after lets say, 30 minutes ?

It looks like there is a very small leak somewhere. I hope its not one of the bags.

Last edited by - Mover -; 05-06-2018 at 03:26 PM.
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Old 05-05-2018, 03:42 PM
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This is the pressure relief valve I'm referring to, if you search the part number number on eBay you will find that you can buy it on it's own, without needing to buy a whole new compressor.

I did however elect to buy a new (used w/37k miles) compressor off eBay from a 2015 CLS because it was only slightly more expensive than the valve itself, and I wanted to rule out any other potential problems as well. The seller was crazy laggy on shipping it out, so I can only install it next weekend, but I will report back if it has fixed the issue. I'll also take my old compressor apart to see the condition of the valve, though I doubt I'll be able to tell as even a fraction of a millimeter out of tolerance can cause issue and that's not really detectable by eyeballing it.

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Old 05-06-2018, 03:12 PM
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When you reinstall used compressor, don't neglect baking the drier granules.
I had mine in dry weather and they were soaking wet when I took the compressor apart.
Commenting on car dropping on one mode and staying on other - we had topics showing cross section of the air bags.
Airmatic is utilizing dual chamber bags for different comfort,
So car dropping in 1 mode and staying on other would indicate leak on 1 chamber.
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Old 05-12-2018, 01:57 AM
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OK, so I got the new (used) pump from the ebay seller, but when I unboxed it I noticed a lot of white crusty stuff inside the main inlet hose. Just out of curiosity I took the pressure relief valve off the pump to see how it worked and this is what I found, see image below. I don't think this is normal, there is a lot of what looks to be oxidation caked onto to valve body, with a little bit of white and brown powder (looks like hard water stain) inside the plastic housing. The seller is from Florida, so I'm suspecting there was water intrusion into the pump, but I don't want to jump to conclusions yet. I contacted the seller about it and sent him the below picture, he got real angry and defensive. Telling me that it was is in "perfect working condition" when on his car and also he's accusing me of "taking his parts" because I opened it.

I'm a bit suspect on installing this onto my car, even to just try it out as I'm worried about contaminating the whole Airmatic system with this oxidation powder in case there is a lot more of inside the rest of the pump. I bought this pump from his because I saw 1410 date on it (assuming 10th week of 2014) and he claimed 37k miles, so I automatically assumed it must be in better condition than mine, and I'd much rather buy a used OEM pump then buy the $250 Chinese remanufactured unit on ebay.

My question to anyone who has rebuilt an Airmatic pump before, have you seen this before? Is this normal? I'm going to take off the pressure relief valve off of my original pump tomorrow and see how it compares. If I see similar conditions then I may just swap them out and eventually rebuild one of them, as I have a feeling I'm going to get a real hard time getting my money back...


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Old 05-12-2018, 09:52 AM
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All compressor condensate water when compressing the air.
That is how physics work. I took apart my compressor when I bought the car, baked granules and still having trouble with the system, took it apart again few months later. In dry California summer the granules got soaked with water to the degree I had water droplets.
That is what happening with any leak, when there is no return air that should push the water in reverse.
So yes, the white water residue is normal.
The compressor seem to be pretty robust and last long time with computer preventing burn out. The only wearable is $20 ring. No need to buy somebody's else troubles.
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Old 05-17-2018, 03:50 PM
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I managed to find a scanner for the car. Very nice guy scanned it for me. Hopefully I could return the favour.

Two codes existed for the suspension. C156784 - The left front vehicle level is outside the tolerance. There is a signal below the permissible limit value.. C156984 - The right front vehicle level is outside the tolerance. There is a signal below the permissible limit value,

I'm not sure if these code are telling me what I see (the car is sitting low in the front end). Obviously, the system is going to realize the car is sitting to low when I start it up. So these codes are telling me something I already see. Not much news here.

Last edited by - Mover -; 05-18-2018 at 10:23 AM.
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Old 05-20-2018, 02:23 PM
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I am soooo f'in baffled right now. I took apart my original pump, expecting there to be corrosion and full of moisture preventing the pressure relief valve from fully closing but NOPE! The thing looked brand new inside, I mean spotless. Yes the desiccant was moist, but otherwise it looked as if it was made yesterday.

I dried the desiccant out in the over until I saw no steam coming off it when scooping it with a clear shot glass, which took 2 hours in the over and 4x 30 second bursts in the microwave. Greased all o-rings with silicon o-ring lubricant, reassembled the pump, placed it back on the car and the damn thing still lowered in sport mode exactly as it did before. I just want to bang my head against the wall. Distro valve block is brand new OEM, pump is now cleaned and dried out, basically brand new, yet the car still lowers through the exhaust tube

At this point all I can think of perhaps the level sensor giving the ECU an incorrect (high) reading and the car tries to release air to bring it level. BUT, before I toss any more parts at the problem, the next part I'm getting is a Star Diagnostic System.

Here is what my pump look like inside, spotless:




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Old 05-20-2018, 02:31 PM
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and for comparison, here is what the eBay pumped looked like on the inside. Complete junk, and the seller is refusing to take it back because I opened it. On the bright site at least I didn't put it on my car and contaminate the whole airmatic system with this crap.





After cleaning the corrosion off with steel wool and CLR I've found the extent of the damage to be terminal, to the cylinder at least. The metal (magnesium maybe?) is just coming apart. I'm now almost certain that this pump was from a flood damaged car, the seller being from Florida. This thing must have acted as a water pump or something.

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Old 05-20-2018, 04:39 PM
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Originally Posted by kajtek1 View Post
Commenting on car dropping on one mode and staying on other - we had topics showing cross section of the air bags.
Airmatic is utilizing dual chamber bags for different comfort,
So car dropping in 1 mode and staying on other would indicate leak on 1 chamber.
It appears the above is going on (with mine at least).

On 'comfort' mode, both chambers have air in them and are connected to each other from what information was passed along to me. The car drops, it just takes alot longer to drop. The guy who scanned mine has an Autel Maxidas DS708. I didn't want to bother him to much. He just scanned for codes but I think it has the capability to do the tests Ungarisch is looking to do.

I might go back to the guy who scanned my car and pay him some $$ to use his DS708 to perform some tests on the suspension.

The pump you got... I wouldn't be surprised if he tried to drive it when the hurricane hit back in September.

Last edited by - Mover -; 05-20-2018 at 04:42 PM.
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Old 05-20-2018, 05:20 PM
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I think I just hit on something big! While reading through the WIS manual on the Airmatic modules and their functions, I've noticed that there is a "locking position, function" that you are supposed to put the car in while jacking it up on a lift. This locking mode is actuated by the "raised mode" button or what the workshop manual calls EN1 mode actuation. It prevents the car from depleting the air in the system, regardless of what the level sensors are reading.

For instance, if you've ever changed a tire you'll know that if you leave the car in Comfort mode, jack up the wheel, when you put the car back on the ground the car sits lower than before, this is because the level sensor things the car is too high and tries to deplete that corner.

However, if you put the car in "raised mode", then jack it up and put it back on the ground, you'll see that the car is the same level as is was before, the car did not deplete the shock like it did in other modes.

Soooo, I think this is making sense why our cars are staying put in raised mode but lowering in other modes. I think the front level sensors are kaput, giving the airmatic computer incorrect readings, and thus the airmatic computer lowering the car to try and level it with these incorrect readings. However, in raised mode, the computer is told to ignore the sensor readings and not lower the car.

Also, I was driving my girlfriend to the gym just now, in raised mode, and I got an Airmatic Malfunction warning, first time ever. So I'm guessing that the sensor is now completely junked whereas before it was intermittent. Tomorrow, I'm going to an MB indie to have the car scanned. I'm hoping to see a sensor malfunction to confirm my theory.

This is from the WIS:


Last edited by Ungarisch; 05-20-2018 at 05:22 PM.
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Old 05-20-2018, 06:21 PM
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I'd also like to add for the record that unlike the old W220/1 and W211 pumps, the pump that comes on newer the W212 and W218 cars the piston ring is pressed in and is not serviceable / replaceable. So if you wore your pump out you are SOL.

The eBay pump is off a 2014 CLS, while mine is off my 2011 E550. Same part number on both pumps, but I have noticed that the 2014 has a different (flat) cylinder o-ring and a machined surface on the cylinder head, while mine is powdercoated.

Here is the 2014 pump for reference:


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Old 05-31-2018, 07:35 PM
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I got my icarsoft and thought I'd share some numbers.


Front of car dropped - These are the voltage readings with the front of the car dropped



Front of car dropped - These are the height measurements



Normal level - voltage readings after starting the car and the compressor bringing the car to normal level



Normal level - These are the height measurements when the car got to normal level

What I found strange was that the left and right side level sensors work differently.

As the left side of the car rises, the voltage drops from the left side level sensors.
As the right side of the car rises, the voltage increases from the right side level sensors.

The left side measures inversely to what the right side measures.

Why in the world would Mercedes set it up like that ?

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Old 05-31-2018, 10:18 PM
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ill just leave this here since i have it , might be good for comparison
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Old 06-07-2018, 09:01 AM
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Very interesting thread, thanks everyone.

My '14 E550 seems to be dropping the right, rear a bit and raising the left, rear overnight. If two fingers between the tire and body is normal (the fronts appear to never move), the LR raises to 4 fingers and the RR drops to 1 finger. There appear to be random, short 'psssst' bursts from the LR shortly after getting out of the car, and for hours later, too.

Conditions are ~70-80F during the day and ~50-60F in the evenings right now in the Northeast.

I will try the raised mode next to see what happens, but it's going in to the dealer on Monday to have a couple things checked out, including this. The car is new-to-me so I'm trying to calibrate what is "normal" for this car. (This does not seem normal). Will report the dealer findings after the visit.

Last edited by mb3ps; 06-07-2018 at 09:07 AM. Reason: inconsistent raise/drop corners - corrected
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Old 06-10-2018, 05:13 PM
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A few more observations.

We have no 'check valve' in the strut to keep it from losing air.

I unscrewed one of the front lines at the strut when it was almost bottomed out. Some air came out and it completely emptied and dropped a little more.
When I started it up with one of the lines off, I noticed air cycled between the 2 front struts. You could hear/feel air coming out of the line that I undid and then it would stop, and start filling the other front strut and then back to the line that I undid. It cycled one and then the other but never both at the same time.

It looks like the level control block has the only valve between it and the strut.
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Old 06-12-2018, 08:37 AM
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I too bought used parts (not MB) from a FL seller. Had the same experience. I'll never buy anything automotive from FL.
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