Quick questions about air suspension
Thread Starter
Junior Member
Joined: Feb 2019
Posts: 21
Likes: 3
Mercedes w212 2012 Wagon
Quick questions about air suspension
Hello. I have replaced the air bags and the valve block on my rear air suspension after having a leak on the right side air bag. It has also been dropping down over night for over a year, however a few weeks ago the right airbag decided to make a big hole.. (2012 wagon only rear air suspension).
After I did this the car rises and everything looks good, however, the car still drops over night. I have ordered new hoses and nipples. Gonna replace them when I get them in the mail. In theory I believe it can only be a tiny leak in one of the lines making the car drop down. The right side is dropping more thean left side, so my guess is the hose going to the right air bag.
My questions are;
Since I changed the valve block, shouldnt that hold the pressure so no air go back to the compressor? If this is the case it eliminiates the compressor being the sinner.
The car rises to approximitly the same height on both sides (+/- 10mm), however, gets more leveled as I drive. But readings in my diagnostics is telling me bigger difference. Is this normal? ( I have changed the sensors as well)
And last; in a perfect world, with the system fully free for leaks. Should the car in theory never drop then? Or will it still let some air out to lower the pressure on the air bags?
Thanks in advance!
After I did this the car rises and everything looks good, however, the car still drops over night. I have ordered new hoses and nipples. Gonna replace them when I get them in the mail. In theory I believe it can only be a tiny leak in one of the lines making the car drop down. The right side is dropping more thean left side, so my guess is the hose going to the right air bag.
My questions are;
Since I changed the valve block, shouldnt that hold the pressure so no air go back to the compressor? If this is the case it eliminiates the compressor being the sinner.
The car rises to approximitly the same height on both sides (+/- 10mm), however, gets more leveled as I drive. But readings in my diagnostics is telling me bigger difference. Is this normal? ( I have changed the sensors as well)
And last; in a perfect world, with the system fully free for leaks. Should the car in theory never drop then? Or will it still let some air out to lower the pressure on the air bags?
Thanks in advance!
MBWorld Fanatic!
Joined: Jun 2020
Posts: 1,363
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'11 E350, '11 E550, '98 M3, '95 E320
Check the air lines between the springs and valve body... on our wagon, one of lines had rubbed against the tire well and caused a pinhole leak (resulting in the right side dropping overnight slowly). Spray down the lines and connectors with soapy solution and get behind all the heat shields.
As far as the valve body leaking [individual circuits], it can be due to wear/age (valves no longer seal 100%) OR its being commanded. The latter can be intentional (would imply sensors or height calibration is off) or not intentional due to a short, corrosion or bad airmatic module. Easy way to check this, unplug the electrical connector from valve body and that will remove the any commands (intentional or not).
There should be no leaks, at least ones you can measure.
As far as the valve body leaking [individual circuits], it can be due to wear/age (valves no longer seal 100%) OR its being commanded. The latter can be intentional (would imply sensors or height calibration is off) or not intentional due to a short, corrosion or bad airmatic module. Easy way to check this, unplug the electrical connector from valve body and that will remove the any commands (intentional or not).
There should be no leaks, at least ones you can measure.
Newbie
Joined: Nov 2020
Posts: 10
Likes: 1
From: New Jersey
2014 e350 Wagon
I'm having the same problem on our W212 wagon - right side airmatic is dropping overnight. Over the next few days I am going to roll up my sleeves and start looking to diagnose the issue before ordering parts. If I am able to provide any useful insights/feedback I'll post here.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Hello. I have replaced the air bags and the valve block on my rear air suspension after having a leak on the right side air bag. It has also been dropping down over night for over a year, however a few weeks ago the right airbag decided to make a big hole.. (2012 wagon only rear air suspension).
After I did this the car rises and everything looks good, however, the car still drops over night. I have ordered new hoses and nipples. Gonna replace them when I get them in the mail. In theory I believe it can only be a tiny leak in one of the lines making the car drop down. The right side is dropping more thean left side, so my guess is the hose going to the right air bag.
My questions are;
Since I changed the valve block, shouldnt that hold the pressure so no air go back to the compressor? If this is the case it eliminiates the compressor being the sinner.
The car rises to approximitly the same height on both sides (+/- 10mm), however, gets more leveled as I drive. But readings in my diagnostics is telling me bigger difference. Is this normal? ( I have changed the sensors as well)
And last; in a perfect world, with the system fully free for leaks. Should the car in theory never drop then? Or will it still let some air out to lower the pressure on the air bags?
Thanks in advance!
After I did this the car rises and everything looks good, however, the car still drops over night. I have ordered new hoses and nipples. Gonna replace them when I get them in the mail. In theory I believe it can only be a tiny leak in one of the lines making the car drop down. The right side is dropping more thean left side, so my guess is the hose going to the right air bag.
My questions are;
Since I changed the valve block, shouldnt that hold the pressure so no air go back to the compressor? If this is the case it eliminiates the compressor being the sinner.
The car rises to approximitly the same height on both sides (+/- 10mm), however, gets more leveled as I drive. But readings in my diagnostics is telling me bigger difference. Is this normal? ( I have changed the sensors as well)
And last; in a perfect world, with the system fully free for leaks. Should the car in theory never drop then? Or will it still let some air out to lower the pressure on the air bags?
Thanks in advance!
What does happen to my car is that when I park it and lock the doors the car lets air out from springs. This I believe is because down force that pulls car down while driving causes the system pump more air in springs for maintaining the level and then when car stops it raises up higher than set level point. After that the car should maintain level other than small changes due to temperature changes that can move it also up.
You mention there is perhaps 10 mm height difference when all is good. This is not a good measurement. If your floor under car is perfectly level there should not be more than just one or two millimeter difference at height measured at each wheel.
Did you have the new level sensors calibrated? I think new sensors need to be calibrated for level.
It would be good to read level at each sensor when the car has lowered and see if the level indeed is different as what the system sees. If it is showing the same level but you can see one side is lower then it likely is a calibration issue.
MBWorld Fanatic!
Joined: Jun 2020
Posts: 1,363
Likes: 1,012
'11 E350, '11 E550, '98 M3, '95 E320
I can't recall the tolerance, but I think it was around +/- 5 mm to the target setting Airmatic maintains. When driving around you'll see more variability, which I've confirmed with Xentry. Don't forget, your riding on springs... unless you have a perfectly flat road, no acceleration or deceleration, turning the wheel... there's going to be motion in the suspension.
Ideally, you'd take an average over a period of time to see if the system is maintaining the correct ride height. Also the system is not adjusting the ride hight continually. Again, I can't remember, but its every x seconds it adjusts if needed.
Agree with Arrie if the sensors are replaced, they need to be calibrated. However it doesn't appear the OP changed them.
Ideally, you'd take an average over a period of time to see if the system is maintaining the correct ride height. Also the system is not adjusting the ride hight continually. Again, I can't remember, but its every x seconds it adjusts if needed.
Agree with Arrie if the sensors are replaced, they need to be calibrated. However it doesn't appear the OP changed them.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
I can't recall the tolerance, but I think it was around +/- 5 mm to the target setting Airmatic maintains. When driving around you'll see more variability, which I've confirmed with Xentry. Don't forget, your riding on springs... unless you have a perfectly flat road, no acceleration or deceleration, turning the wheel... there's going to be motion in the suspension.
Ideally, you'd take an average over a period of time to see if the system is maintaining the correct ride height. Also the system is not adjusting the ride hight continually. Again, I can't remember, but its every x seconds it adjusts if needed.
Agree with Arrie if the sensors are replaced, they need to be calibrated. However it doesn't appear the OP changed them.
Ideally, you'd take an average over a period of time to see if the system is maintaining the correct ride height. Also the system is not adjusting the ride hight continually. Again, I can't remember, but its every x seconds it adjusts if needed.
Agree with Arrie if the sensors are replaced, they need to be calibrated. However it doesn't appear the OP changed them.
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Thread Starter
Junior Member
Joined: Feb 2019
Posts: 21
Likes: 3
Mercedes w212 2012 Wagon
Hello all, and thanks for the replies.
I changed the hoses, but no luck there, however I talked to the shop where I bought the new springs and got told how to leak test the springs it self. (take them out of the car and take of the entire protective rubber, then fill with air from a compressor and use soapy water.) As it turns out, there was a tiny crack in the body of the spring causing a tiny leak. The shop sent me a new one wich will arrive tomorrow. Have a good feeling all will be good then!
About the sensor: I don't believe they need calibrations since they are static sensors, I may be wrong though, but the readings it gives me is the same as the old sensors.
I believe the bracket for the sensor on the right side have been twisted a little bit when everything was rusted in place and nothing moved so that may be why I have level differences. Not gonna do anything about that until the leak is fixed, but I have 2 replacement arms for the sensor that I can adjust so that may be the solution to that.
I think that if the bracket is bent 2-3mm it would be a lot more on the sensor reading than 2-3mm.
For my diagnose and reading levels I use iCarsoft MB II.
I changed the hoses, but no luck there, however I talked to the shop where I bought the new springs and got told how to leak test the springs it self. (take them out of the car and take of the entire protective rubber, then fill with air from a compressor and use soapy water.) As it turns out, there was a tiny crack in the body of the spring causing a tiny leak. The shop sent me a new one wich will arrive tomorrow. Have a good feeling all will be good then!
About the sensor: I don't believe they need calibrations since they are static sensors, I may be wrong though, but the readings it gives me is the same as the old sensors.
I believe the bracket for the sensor on the right side have been twisted a little bit when everything was rusted in place and nothing moved so that may be why I have level differences. Not gonna do anything about that until the leak is fixed, but I have 2 replacement arms for the sensor that I can adjust so that may be the solution to that.
I think that if the bracket is bent 2-3mm it would be a lot more on the sensor reading than 2-3mm.
For my diagnose and reading levels I use iCarsoft MB II.
