Hi!
I've w220 with couple of airmatic issues.

One is air leak:
Changed rear right airbag, still the same.
Checked pressure control block, found some leak there, sealed with epoxy. Car stood fine for one night, another night found it on the ground.
Undid pressure line from compressor to valve block, and sprayed soapy water, bubbles coming out. As I understand it is internal leak? Even if so, shouldn't compressor hold the pressure?

Rear level sensor?
When one wheel sinks (because of that leak) I start the car and it raises, sometimes. Sometimes not. Could it be because it is one sensor for the rear, and it doesn't see drop all the time?

Compressor moody:
On my way to the city got "Airmatic malfunction", didn't paid much attention, because I know I have leak, and compressor turns of after some time, and gives malfunction message. When restarted the compressor didn't engaged, and car sinked to the bottom, gave me message "Stop too low", compressor still didn't engaged. Though compressor went.
Pulled relay, shortened contact, compressor working. Checked what voltage is given to relay-> 9V. Swapped relay with another one, nothing.
Closed the door, opened, locked car, unlocked, started engine, drove 1m back and forth, measured voltage at relay port-> 14V, put in relay VOILA! Working. But until next time.
Why sometimes it kicks in, and sometimes don't? What is controlling that? Level sensor is not suspect there, as display shows "too low".

 

Watch this video...


Hope it helps...

 

Do You believe, that valve block internal leak (external fixed) could cause only one wheel to fall?

 

If the o-ring for that valve failed, then it would behave much like what you're experiencing right now.

 

Than I have to give it a try to cheap ebay valve block, and see, if that changes anything.

It does not explain weird compressor behaviour, though.

 

Now I went to the car and rear is on the ground.

Compressor doesn't engage, despite it shows "too low". So clearly it is not an issue with level sensor. Power to relay 9V, or nothing.

Does somebody knows more about electrical part of airmatic. What is giving power to relay to actuate compressor?

 

https://w220.ee/Airmatic

 

Thanks for the link. Already spent much time on that page, searching for the answer, but was unable to find why compressor does not work, when car too low. Compressor is good.

 

Today, I've got my diagnostic tool, and hooked it up to see what's happening.

Current situation was, rear sitting on the ground, compressor doesn't engage, nor it shows too low.

After some time it decided to turn on compressor, so data has changed a bit.

Test results:


================================================== ======================
BENZ_EN_TEST_00001>S(220)>Up to 08-2002>Gasoline>220.175 - S 500-55 AMG>Manual>Suspension>View Data>Vehicle level:
Total Frames: 2 , Supported Items: 3
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 1/2:
Left front vehicle level ----- 58mm
Rear vehicle level ----- -24mm
Right front vehicle level ----- 30mm
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 2/2:
Left front vehicle level ----- 58mm
Rear vehicle level ----- -24mm
Right front vehicle level ----- 30mm

================================================== ======================
BENZ_EN_TEST_00001>S(220)>Up to 08-2002>Gasoline>220.175 - S 500-55 AMG>Manual>Suspension>View Data>Vehicle level:
Total Frames: 5 , Supported Items: 3
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 1/5:
Left front vehicle level ----- 28mm
Rear vehicle level ----- 6mm
Right front vehicle level ----- 20mm
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 2/5:
Left front vehicle level ----- 28mm
Rear vehicle level ----- 6mm
Right front vehicle level ----- 21mm
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 3/5:
Left front vehicle level ----- 28mm
Rear vehicle level ----- 6mm
Right front vehicle level ----- 20mm
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 4/5:
Left front vehicle level ----- 28mm
Rear vehicle level ----- 6mm
Right front vehicle level ----- 20mm
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 5/5:
Left front vehicle level ----- 28mm
Rear vehicle level ----- 6mm
Right front vehicle level ----- 20mm

================================================== ======================
BENZ_EN_TEST_00001>S(220)>Up to 08-2002>Gasoline>220.175 - S 500-55 AMG>Manual>Suspension>View Data>Level Sensors:
Total Frames: 2 , Supported Items: 6
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 1/2:
Signal 1 0f component B22/3(Rear axle level sensor) ----- 3.06V
Signal 1 of component B22/8(Left front level sensor) ----- 2.08V
Signal 1 of component B22/9(Right front level sensor) ----- 2.16V
Signal 2 0f component B22/3(Rear axle level sensor) ----- 2.02V
Signal 2 of component B22/8(Left front level sensor) ----- 3V
Signal 2 of component B22/9(Right front level sensor) ----- 2.92V
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 2/2:
Signal 1 0f component B22/3(Rear axle level sensor) ----- 3.06V
Signal 1 of component B22/8(Left front level sensor) ----- 2.08V
Signal 1 of component B22/9(Right front level sensor) ----- 2.16V
Signal 2 0f component B22/3(Rear axle level sensor) ----- 2.02V
Signal 2 of component B22/8(Left front level sensor) ----- 3V
Signal 2 of component B22/9(Right front level sensor) ----- 2.92V

================================================== ======================
BENZ_EN_TEST_00001>S(220)>Up to 08-2002>Gasoline>220.175 - S 500-55 AMG>Manual>Suspension>View Data>Acceleration sensors:
Total Frames: 2 , Supported Items: 3
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 1/2:
B24/3(Left front body acceleration sensor) ----- 2588mV
B24/4(right front body acceleration sensor) ----- 2549mV
B24/6(right rear body acceleration sensor) ----- 2471mV
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Frame 2/2:
B24/3(Left front body acceleration sensor) ----- 2588mV
B24/4(right front body acceleration sensor) ----- 2529mV
B24/6(right rear body acceleration sensor) ----- 2471mV


It does see change in height, but I assume it is not correct, because when car was raised it showed only 6mm rear height.

Also pressure system is showing all the same values in pressure tank, and all shocks. I know it is not true, because it stood fine on the front, but still showed 0bar, when car was rear down.

What does it say?

 

Meassure the pressure output of the Compressor. It shall be >13bar. In my opinion the compressor is weak/defect, and can't deliver either pressure and/or amount of compressed air

 

Not really. I see 17bar on diagnostic computer. And as I wrote before, compressor doesn't kick in at time it suppose to, so it has nothing to do with it's pressure delivering capabilities.

 

Yesterday I've started the car it raised, and I left it without locking it. What I've noticed, that after couple of hours it is not sinking. So I left it unlocked during the night.
Now it is more than 24 hours, and it is still on the same level?

So where is the leak now?

It seems like, it has something to do with sleep mode. Does anyone has any experience with it?

 

I still believe that the compressor is the issue. When you lock the car, the Airmatic system reliefs some pressure. Unlocked it doesn't. It is either the compressor itself, or the pressure relief valve attached to the compressor. What you can do is, to check the electric connectors an cables at the compressor for corrossion. Maybe, as well, the valve doesn't close correctly? You can check the compressor pressure directly, by removing the airsupply hose from the valve block and attach a pressure gauge to the line. Run the compressor by attaching a wire jumper to the relay socket. Let the compressor run until you reach >13-15 bar. Take out the jumper and let the whole arrangement sit for 1-2h. The pressure should Not significantly drop over time. BTW the Airmatic control unit stops the pressure loading by the compressor in case there is an overflow in time to charge the system, and if the pressure values are not reaching certain thresholds.

 

Could be so. BTW, yesterday, I've moved the car 5 meters, and didn't locked it. BUT, found rear on the ground this morning.

I believe, that it could be valve block, maybe pressure valve, and also release valve on compressor.

I don't fancy throwing parts at it, but I have to start somewhere.

Do You know if compressor is the same at w221? I could swap them for the sake of test.

 

Just looking at the type numbers both compressors are different. So I cant confirm the swap would work. But as I think you are very good at DIY, it would be worth a try, as the Airmatic Systems of the two cars are pretty much identical. Did you already check the system if there are any leaks, especially at the fittings?

do you know this?
https://nemigaparts.com/cat_spares/epc/mercedes/1/

 

Thanks for the link. Didn't knew that.

I've checked for the leaks on valve block. It had some bubbles, so I've put some epoxy on connections, not that part is fine. The only leak I have now is from valve block, back to compressor. (I've diagnosed it by unscrewing compressor hose from valve block, and spraying soap inside hole- bubbles coming out)

So, if valve block leaking back to compressor and compressor relief valve doesn't seal properly it goes out.

What is very interesting, is that sometimes it sinks in two hours, sometimes it doesn't in 24. ?

 

Some of the valve blocks can be rebuilt - usually, just cleaning and new O-rings. Kits are probably available on-line.

 

Hi!

I couldn't find any repair kits, except for ABC system. But I've found, that I could buy chinese replacement for around 100eur.

 

Don't you buy cheap crap, it make you only do the whole twice. It's not worth it!!!! What you took of the valve block, was the feeding line from the compressor to the valve block. If the car sits properly, you can take off the feeder line, w/o the car dropping, as the 4valves should hold the pressure. In addition each strut has a pressure valve to hold a minimum pressure in each strut, to prevent total loss of air pressure. Do you know this site?
www.W220.ee
here you can see all the details about Airmatic

 

Hi!
Yes, I know that site. Very helpful. I understand, that it all lines should hold pressure independently. When I undo air supply hose and have air leak from there, it tells me, that some of those lines is not holding pressure, so it is leaking to supply. That shouldn't be a problem, as compressor itself should hold the pressure, when line is in place.

Now car sits fine, unused like 4-5 days.

What I suspect, is that compressor air relief valve sometime sticks open, after going into sleep mode. Because, what else could cause leaking to empty in couple of hours, and another time sitting fine for couple of days?

 

The air relieve valve is a very simple part. You can take it off, and disassemble it, for cleaning, an maybe replacing O-rings. Watch out when you take it apart, that you put back the parts in the sequence. Unfortunately this valve cannot be bought individually, only along with new compressor. And additionally check the cable connectors of the compressor and the valve block, as they tend to corrode, even into the wires sometimes.

 

Now it is two weeks, when car sits fine, but I have never run, or even opened it. So it should be air compressor relief valve. I'd like to do simple test test to make sure, and here comes a question.
If I remove compressor relay, will it disengage pressure relief valve, or is it controlled by some other wiring?
I guess, that, if I would disable it, and drive around for couple of miles, it should not get lower?

 

The compressor relay only switches on the compressor. If you remove it, besides the Airmatic warning, you'll lower the body over time, since no recharge is there anymore. The air in the system is not shifted in a closed circuit, but will be released/recharged as Airmatic is operating. The pressure relief valve is operated by the control module inside the fuse box driver side. If you think this valve is not closing tightly enough, just take it out, clean it and, if available, renew the O-rings. Maybe you can just swap the valve between the W220 and the W221, possibly there are interchangeable for test purpose?

 

Ok, I will try to clean it, as soon, as weather improves.

 

But be carefull taking it apart, and take pictures so you get the parts together in the right sequence and position.