W211 Airmatic problems
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From: L.A., Moscow, NYC, San Diego, Baja
1998 E320 Wagon, 2003 W211 E500, 2003 W211 E500, 1999 W210 E55 AMG
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Disclaimer: never worked on MB airmatics; however, did some bus air suspension in my youth.
can you measure pressure at the different junction points? Say after the splitter in the rear? At the entry point of the airstrut?
You got pressure so you are good. From there it is just about continuing measuring until you get to the unit. Pressure at the entry of the unit, it does not mean it will raise since the entry valve can be stuck closed, so no air in. Say the module at the top is not working, so no inflation
My 2c
can you measure pressure at the different junction points? Say after the splitter in the rear? At the entry point of the airstrut?
You got pressure so you are good. From there it is just about continuing measuring until you get to the unit. Pressure at the entry of the unit, it does not mean it will raise since the entry valve can be stuck closed, so no air in. Say the module at the top is not working, so no inflation
My 2c
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W202 S211
Disclaimer: never worked on MB airmatics; however, did some bus air suspension in my youth.
can you measure pressure at the different junction points? Say after the splitter in the rear? At the entry point of the airstrut?
You got pressure so you are good. From there it is just about continuing measuring until you get to the unit. Pressure at the entry of the unit, it does not mean it will raise since the entry valve can be stuck closed, so no air in. Say the module at the top is not working, so no inflation
My 2c
can you measure pressure at the different junction points? Say after the splitter in the rear? At the entry point of the airstrut?
You got pressure so you are good. From there it is just about continuing measuring until you get to the unit. Pressure at the entry of the unit, it does not mean it will raise since the entry valve can be stuck closed, so no air in. Say the module at the top is not working, so no inflation
My 2c
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
You may need to find the wiring diagram. If I understand correctly there is three pin connector at the top of the unit: ground, inflate, deflate. If the inflate is not active, the unit will not inflate regardless of entry pressure.
Find a way to measure pressure as close as possible to the unit, physically or electronically, and verify there is voltage at the connector to allow the valve to open. Basically, there are 3 possible point of failure at the entry: voltage, pressure, valve hardware. If the first two pass, i.e you got correct voltage and pressure, the problem is downstream; otherwise, trace the failing one backwards
Is it possible to introduce some kind of T junction for a pressure gauge?
Detach the electrical connector from the top of unit, and measure the voltage on both actuator pins, you want inflate
No other ideas, sorry.
Find a way to measure pressure as close as possible to the unit, physically or electronically, and verify there is voltage at the connector to allow the valve to open. Basically, there are 3 possible point of failure at the entry: voltage, pressure, valve hardware. If the first two pass, i.e you got correct voltage and pressure, the problem is downstream; otherwise, trace the failing one backwards
Is it possible to introduce some kind of T junction for a pressure gauge?
Detach the electrical connector from the top of unit, and measure the voltage on both actuator pins, you want inflate
No other ideas, sorry.
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W202 S211
You may need to find the wiring diagram. If I understand correctly there is three pin connector at the top of the unit: ground, inflate, deflate. If the inflate is not active, the unit will not inflate regardless of entry pressure.
Find a way to measure pressure as close as possible to the unit, physically or electronically, and verify there is voltage at the connector to allow the valve to open. Basically, there are 3 possible point of failure at the entry: voltage, pressure, valve hardware. If the first two pass, i.e you got correct voltage and pressure, the problem is downstream; otherwise, trace the failing one backwards
Is it possible to introduce some kind of T junction for a pressure gauge?
Detach the electrical connector from the top of unit, and measure the voltage on both actuator pins, you want inflate
No other ideas, sorry.
Find a way to measure pressure as close as possible to the unit, physically or electronically, and verify there is voltage at the connector to allow the valve to open. Basically, there are 3 possible point of failure at the entry: voltage, pressure, valve hardware. If the first two pass, i.e you got correct voltage and pressure, the problem is downstream; otherwise, trace the failing one backwards
Is it possible to introduce some kind of T junction for a pressure gauge?
Detach the electrical connector from the top of unit, and measure the voltage on both actuator pins, you want inflate
No other ideas, sorry.
Last edited by Revolli; Oct 16, 2021 at 04:58 PM.
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Anything is possible but you need to establish a reference point when troubleshooting a system, and systematically move upstream/ downstream based on factual information w/o jumping steps. Otherwise, it becomes a frustrating guesstimate game.
IF, big if, the system has a failsafe mechanism, i.e. shutdown whenever detects a problem you need to find/catch the problem before the failsafe is triggered, say 10s?
Airmatics videos for the W211
IF, big if, the system has a failsafe mechanism, i.e. shutdown whenever detects a problem you need to find/catch the problem before the failsafe is triggered, say 10s?
Airmatics videos for the W211
Last edited by JCM_MB; Oct 16, 2021 at 07:30 PM.
Thread Starter
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W202 S211
Anything is possible but you need to establish a reference point when troubleshooting a system, and systematically move upstream/ downstream based on factual information w/o jumping steps. Otherwise, it becomes a frustrating guesstimate game.
IF, big if, the system has a failsafe mechanism, i.e. shutdown whenever detects a problem you need to find/catch the problem before the failsafe is triggered, say 10s?
Airmatics videos for the W211
https://youtu.be/PtY9Cr7QPbw
IF, big if, the system has a failsafe mechanism, i.e. shutdown whenever detects a problem you need to find/catch the problem before the failsafe is triggered, say 10s?
Airmatics videos for the W211
https://youtu.be/PtY9Cr7QPbw
Last edited by Revolli; Oct 16, 2021 at 07:08 PM.
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Be careful, you can change every single component and still end up with a problem, same or different.
If the assumption is the airbag is good, whatever that means, you must verify that there is the correct pressure at the entry point, not elsewhere, and valve is activated for inflation, voltage. If you do not have the computer diagnostic, you may have to do the old ways: measuring with gauges, voltmeters, and tedious tracing the flow of information: neumatic and electric.
For example, the pressure at the pump is 15bar, the line is clogged downstream, there will be no leaks, no raise. You need to check at the important points and troubleshoots where the data leads you
If the assumption is the airbag is good, whatever that means, you must verify that there is the correct pressure at the entry point, not elsewhere, and valve is activated for inflation, voltage. If you do not have the computer diagnostic, you may have to do the old ways: measuring with gauges, voltmeters, and tedious tracing the flow of information: neumatic and electric.
For example, the pressure at the pump is 15bar, the line is clogged downstream, there will be no leaks, no raise. You need to check at the important points and troubleshoots where the data leads you
Last edited by JCM_MB; Oct 16, 2021 at 08:31 PM.
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W202 S211
Update: So... Since the air lines on my valve block are not marked by any colours I have always connected them like they were when I have reciever the car so I have tried to play around and switch them with each other. Compressor air line was put into the Rear axle distrubutor's position Central reservoir airline was put into the compressor's position
Rear distributor airline was in Central reservoir's position.
After I connected everything like it should I finally have pressure in the airlines and I have found a minor leak in rear distributor.
Rear distributor airline was in Central reservoir's position.
After I connected everything like it should I finally have pressure in the airlines and I have found a minor leak in rear distributor.
Last edited by Revolli; Oct 17, 2021 at 09:18 AM.
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Update: So... Since the air lines on my valve block are not marked by any colours I have always connected them like they were when I have reciever the car so I have tried to play around and switch them with each other. Compressor air line was put into the Rear axle distrubutor's position Central reservoir airline was put into the compressor's position
Rear distributor airline was in Central reservoir's position.
After I connected everything like it should I finally have pressure in the airlines and ai have found a minor leak in rear distributor.
Rear distributor airline was in Central reservoir's position.
After I connected everything like it should I finally have pressure in the airlines and ai have found a minor leak in rear distributor.
.That means someone was messing around the valve block before
. Not a bad idea to tag those lines with some colors. Hope you did not spend too much in parts that may have not been needed.Once you fix the minor leak, give it a nice wash, polish and enjoy a nice ride
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W202 S211
Glad to hear you are out of the woods.
That means someone was messing around the valve block before. Not a bad idea to tag those lines with some colors. Hope you did not spend too much in parts that may have not been needed.
Once you fix the minor leak, give it a nice wash, polish and enjoy a nice ride
.That means someone was messing around the valve block before
. Not a bad idea to tag those lines with some colors. Hope you did not spend too much in parts that may have not been needed.Once you fix the minor leak, give it a nice wash, polish and enjoy a nice ride
And about the parts well...At least now I know they wont break any time soon, or at least shouldn't break.
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I hope you understand that is someone glue it when it shouldn't, and pressurized the system before the glue dried completely, your line downstream may be compromised, i.e. clogged. Even worse that glue may have found its way into the entry of the unit. That is why there is a filter up front of the car . It seems you need a new rear distribution box, and diagnose the line is CLEAN downstream. I would disconnect from the air strut and check air flows properly, again measure pressures.
Here another thread https://www.benzworld.org/threads/wh...-part.3063354/
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W202 S211
For now my car raised itself I'll keep my eyes on heigh levels and pressure in the system to see if it drops or changes. For now I'm not getting any Malfunctions I'll check in with the car in 12 hours and I'll see how it goes.
About the glue it looks like it was dry I althogh I saw some glue leftovers in rear distributor itself. I have bought a new one and changed it. Thanks for the info
About the glue it looks like it was dry I althogh I saw some glue leftovers in rear distributor itself. I have bought a new one and changed it. Thanks for the info
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W202 S211
Someone who worked on this car before me it looks like he did not know what was he doing or he did not really care... Thats why I was surprised about my problem becouse I have never seen something like this in any forums. And I do wonder why Mercedes made plastic threads everywhere for example rear air distributor, compressor and struts.
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W202 S211
Last edited by Revolli; Oct 17, 2021 at 03:49 PM.
Thread Starter
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Joined: Oct 2021
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W202 S211
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W202 S211
Update: I came back to the garage rear left side looks lower than the right side. Rear axle height dropped by 17mm I'm not sure if the right side dropped becouse of extra load from the left side or is it leaking too 
But I get no malfunctions this time on instrument cluster.
But I get no malfunctions this time on instrument cluster.
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That is good news, but the next steps may be w/o the computer help.It seems the left side is the main problem. I understand the air-strut's valve can keep the air within the strut even if disconnected once filled. I think the next step is to find the air leak on the strut itself, i.e. soapy water test?
I have not done a soapy water test in 30 years, but I think it is a lot easier these days:
1 - You need another set of eyes, and good memory --> record it using your phone or else. This allows you to go over the video in case you did not see anything obvious.
2 - Also, eyes are not that great to capture at a distance in closed quarters, poor lighting; however, hearing it is a wonderful thing --> use a microphone attached to a stick and move it (record as well) around the strut. Air leaks are usually at the top near the entry point, or from the bottom where the bag hugs around the cylinder. If dirt comes into the lower half and gets trapped between the bag and the cylinder, the strut will start leaking at some point (at least that used to happens 30+ years ago)
3 - If you are still wondering if the right unit is correct, you can disconnect the electric connector at the top once at the right height so the computer does not deflate it in an attempt to level the car. That will isolate the real (and hopefully only) culprit.
You really need to fix the leak, or it will wear the compressor out at some point and you will be back to square 1.
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Update: I came back to the garage rear left side looks lower than the right side. Rear axle height dropped by 17mm I'm not sure if the right side dropped becouse of extra load from the left side or is it leaking too But I get no malfunctions this time on instrument cluster.
But I get no malfunctions this time on instrument cluster.
