A little perplexed.... AirMatic Suspension.

[MangoMan]

I'll be as brief and just explain it how it is.

I just get the impression that the AirMatic Suspension on my 2000 w220 s500 sits low at the Front - looks ok at the Rear.

So I did a 24 Hour Check, (11am to 11am) on leaving the car undisturbed for 24 hours and doing some measurements. (These are from the bottom edge of the Wheelarch to the centre of the 3-Pointed Star on the Wheel).

Below are the Measurement I recorded.



These are within +/- 0.5mm

Please note, my driveway is slightly slanted down from right to left facing front. ie Left side of car lower than right as parked.

Thoughts please?


NB. There is one more piece to the puzzle but I would rather deal with this first and get it out of the way please.

 

[brucemillar]

Are you attempting establish if you have a leak or, a problem like a leak?

My experience of airmatic on several differing makes & models including Range Rover, BMW & Mercedes is (remember that this is "my experience").

* The suspension will settle when the car is left parked for any length of time. This is not uniform between cars, models etc. So you cannot measure one cars settlement and compare it against another of the same vintage, model etc. This happens for a variety of reasons, none of which should cause alarm, unless you come out to find the car sat on it's bump stops. In the main it is seepage through the pipes, air bags, compressor etc. ALl of these can be tested, usually with bucket of water mixed with Fairy liquid and brushed or poured over where you wish to check. Any visible bubbling would tend to suggest that you have a leak that is greater than "designed" but it will most certainly let the car settle on that corner, nearest that bubbling.

When we switch on the ignition the system primes itself every time. It does so by checking & testing a battery of sensors that check (not in this order)

Height of each corner.
Time to lift & lower each corner.
Pressure of each corner.
Temperature of Compressor motor.
Cross match values against other values to ensure that they are level.
There are more (but I do not recall them all)

After it's start up test. It will (assuming it has found nothing catastrophic) attempt to level the car and check again (usually while you are mobile) but it will also do so at traffic lights etc.

Some conditions will cause the ECU to remove power from the system, giving the impression that it has fused, blown a relay or lost all power. It is ften the case that the system is now in "lock down" and will not re-start until you re-set the error code(s) with a computer or STAR system.

It is also interlocked, in an attempt to try and stop people trapping themselves withing the car, raising/lowering action (you need to be careful not to have the car decide to lower itself when you are lying underneath it).

There is a chap on the Internet call www.bagpipingandy.com

Andy is worth a call and a look at his web site. He may cater for your car and save ou ots of cash. He provides repair and refurbishment kits for WABCO and others that are DIY kits and excellent value for money.

Let me know if this helps or if I am talking nonsense?

 

[MangoMan]

Thanks Bruce.

I certainly appreciate your input - especially the Link!

I basically understand the operating principles of operation of the Airmatic on Mercedes - in fact an acceptable "Seepage", as you put it is amazingly 2mm/hour! It is stated that that in an "undisturbed-test" as I did a drop of 20mm can be acceptable over a 10 hour period! Well mine was over a 24 hour period. (More or less).

The thing that is in question as far as I'm concerned is how the car sits generally. I have uploaded a photo that I took just after I had parked the car in the driveway. (I reversed in this time - not normal practise).

I will await more comments, but I thank you for your time in responding - always appreciated.

 

[renault12ts]

I think it looks fine. But your wheels need refurbed.

 

[brucemillar]

I think it looks fine. But your wheels need refurbed.

It does look good. But gives no clues to what is happening in real life? The front we see, looks almost on the verge of rubbing but may be fine. The only real way to tell is to get it it on level ground with a tape measure.


Sent from my iPhone using Tapatalk

 

[renault12ts]

They look like the correct wheels and, as such, my suspension, on the same wheels, can go much lower...with no rubbing.

 

[MangoMan]

It does look good. But gives no clues to what is happening in real life? The front we see, looks almost on the verge of rubbing but may be fine. The only real way to tell is to get it it on level ground with a tape measure.
Sent from my iPhone using Tapatalk

Albeit at a slight slant from left to right in the photo, the ground is level. And to be honest even if I do park on the flat and level it looks exactly the same.

The first piece of the puzzle as mentioned in my original post is that I did take earlier measurements about 2-3 weeks ago, (measured in the same position) and compared to the measurements taken yesterday the Rear has dropped an average of 10mm and the Front and average of 25mm. The whole car has dropped an average of 17.5mm over the 4 corners.

The second piece is that when I press the Raise Button, (the car should raise up to 50mm) although the Pump starts it does not go up, even though the Readout is saying "Vehicle is Raising".


I also hear the Pump at other times. Although I have to say that when I first got the car I would hear the Pump very rarely operate, and if so only for a couple of seconds compared to the increased duration and noise it makes now.

Personally, I get the feeling the Pump, although working, is not actually "Pumping" and slowly over time the car is slowly just going down. More at the front because of the extra weight of the Engine.

If it were a leak it would collapse fast.

 

[renault12ts]

The pump is fubar.

 

[MangoMan]

They look like the correct wheels and, as such, my suspension, on the same wheels, can go much lower...with no rubbing.

Hi. Thanks.

According to the VIN Data there were Shell modifications upon manufacture.....

"774 SHELL MODIFICATION FOR AMG-WHEELS"....

** The complete Text**

Model S 500 Engine 113960 30 165699
Transmission 722633 01 975357
Order Number 0 9 212 11215
Order Location BERLIN BRANCH
Interior LEATHER SAFFRON (264A)
Paint 1 AZURITE BLUE - METALLIC (366U)
Delivery Date 2000-04-17
Code Description
200A LEATHER
205 OWNERS MANUAL AND SERVICE RECORD - ENGLISH
231 GARAGE DOOR OPENER
249 INSIDE AND OUTSIDE MIRROR AUTOMATIC DIMMING
275 MEMORY PACKAGE (DRIVER SEAT, STRG. COL., MIRROR)
278 TELEPHONE PRE-INSTALLATION COMPL. D-NET
284 SELECTOR LEVER, WOOD
289 WOOD/LEATHER STEERING-WHEEL
352 COMAND
401 DELUXE FRONT SEATS WITH VENTILATION AND HEATING CO
414 ELECTRIC TILT/SLIDE SUNROOF IN GLASS VERSION
461 INSTRUMENT WITH MILES IND. AND ENGLISH LEGEND
540 ROLLER BLIND, ELECTRIC, FOR REAR WINDOW
551 ANTI-THEFT/ANTI-BREAK-IN WARNING SYSTEM
596 HEAT INSULATING+IR REFLECTG.SAFETY GLASS ALL-ROUND
600 HEADLAMPS - CLEANING EQUIPMENT
617 XENON HEADLAMPS, LEFT-HAND TRAFFIC
673 HIGH-CAPACITY BATTERY
731 WOOD TRIM BURRED WALNUT ROOT
774 SHELL MODIFICATION FOR AMG-WHEELS
792 AMG-WHEELS SQUEEZE-IN DEPTH
800 CHANGE OF MODEL YEAR, THE LAST FIGURE SHOWING THE NEW MODEL YEAR
813 LINGUATRONIC-GERMAN (VOICE OPERATION)
816 REMOTE CONTROL FOR RADIO /COMMAND (OMS)
819 CD CHANGER
872 REAR SEAT BENCH HEATING LEFT UND RIGHT
882 INTERIOR SAFEGUARD
883 POWER CLOSING SYSTEM
984 COC DOC., DELETION OF VEHICLE REGISTRATION DOC.

 

[renault12ts]

792 AMG-WHEELS SQUEEZE-IN DEPTH

Love it.

 

[brucemillar]

Usually what we find here is at when the pump stats to "go south" it will also start to run to hot, as it attempts to keep up with any leaks. This in turn allows the compressor to wear out the piston ring.

The solution is to either go to Andy (in the link) or Mercedes and buy a new pump (after you have had it checked out first) It does sound like like it is not holding pressure. Sadly this means the pump will run almost constantly until it just burns out or gives up.

 

[AndrewOl]

Probably a leak in the system. Usually one of the bags. Pump runs more and more to keep up and wears the piston ring out which means it doesn’t generate enough pressure. Hence it running longer and longer. New or refurbished pump will end up the same if you don’t find the leak. For me I changed the pump first that helped identify the leaking rear air bag. Changed that and all good at the moment.

 

[MangoMan]

Thanks for all the comments so far.

I first thought of a leak aswell. But if it is a leak it would go down rather quickly - this is not. 5mm reduction in 24 hours is well below the accepted norm of 2mm/hour. More than 2mm/hour indicates a leak.

To me it just seems that although the pump is pumping it is not putting out enough pressure to generate a increase of height to the standard level, resulting in the whole system slowly going down. (As it would anyway as the system is not 100% leakproof).
Don't forget it has taken more than 2 weeks to lose an average height loss of 17 odd millimetres, or about 3/4 of an inch. Surely if there was a leak it would be flat by now. Also sometimes I don't start the car for 2-3 days but it still stays up.

Look, I hear what you are all saying but if it did have a leak it must be so slight - and if it was so slight why does the Pump not raise the car if the Pump is good?

Anyway, I think I am going to get a Pump Kit from Andy and see what happens.

 

[brucemillar]

If you go for Andy’s kit? It is really worth taking a look inside your head bore for any scoring. Mine was scored so I ended up replacing it as it will let air past. His prices are good if you needed to replace that part.


Sent from my iPhone using Tapatalk

 

[MangoMan]

If you go for Andy’s kit? It is really worth taking a look inside your head bore for any scoring. Mine was scored so I ended up replacing it as it will let air past. His prices are good if you needed to replace that part.
Sent from my iPhone using Tapatalk

Thanks Bruce.

Yes, I have been in contact with Andy and he concurs that it is the Pump at fault with the Symptoms I am having. If not that, then a Valve somewhere blocked or jammed. He doubts very much that it is a leak because the loss levels are well within the prescribed limits, it's just that the loss isn't being replenished by the Pump even though it is apparently Pumping.

 

[brucemillar]

Thanks Bruce.

Yes, I have been in contact with Andy and he concurs that it is the Pump at fault with the Symptoms I am having. If not that, then a Valve somewhere blocked or jammed. He doubts very much that it is a leak because the loss levels are well within the prescribed limits, it's just that the loss isn't being replenished by the Pump even though it is apparently Pumping.

Hi

It’s great you are in touch with Andy. He is a very clever guy with these systems and his help for me was above & beyond.

Try to keep in mind the principle that the system is working on:

It wants to keep a set pressure at measured sensors/points.

Pressure then translates to height along with a bag full of other sensor readings.

This is all good until.... the system recognises to keep its level point it has to keep pumping air.

This excessive pumping eventually trashed the internals. Usually by the piston being constantly run. It scores the barrel, ring and wears the guts out.

The Range Rover guys sometimes fit an LED to the pump then the dash. This shows when it’s running and allows you some chance to diagnose errors before it eats itself.

Not ideal. Most leaks become apparent by dropping a corner as a bag punctures.


Sent from my iPhone using Tapatalk

 

[MangoMan]

Hi Bruce....

Thanks - I've been reading up on the system so I get the gist of it - more or less..... But why Mercedes decided to put the Pump where it is is beyond me! There must have been better options!!

I managed to get to the Pump before the heavens opened and took a few snaps - looks in pretty poor shape! Al;so I believe the Pump Inlet Pipe looks split, but not sure if all the way through - but definitely not good as I think it is after the Filter! (Not sure). There is also a bit of a Heath Robinson jobby on one of the Mountings.
I have to say that the Valve Body looks different to what I have seen in photos and videos...???

Anyway, I'm going to order the Pump Kit anyway. If the result is the same then maybe look at other things. I did used to hear the Pump previously but it only ran for maybe a second or two and was hardly audible. Now you can hear it over the Engine with the door and window closed. Actually you can almost feel it...!!!

Do you think I should check the Pump before I order the Kit Bruce?

Thanks....

It was weird that when I jacked up the car and put it on Stands the car stayed level...??

Ciao.

 

[brucemillar]

Hi Bruce....

Thanks - I've been reading up on the system so I get the gist of it - more or less..... But why Mercedes decided to put the Pump where it is is beyond me! There must have been better options!!

I managed to get to the Pump before the heavens opened and took a few snaps - looks in pretty poor shape! Al;so I believe the Pump Inlet Pipe looks split,

Do you think I should check the Pump before I order the Kit Bruce?

Thanks....

It was weird that when I jacked up the car and put it on Stands the car stayed level...??

Ciao.

This is always the difficulty with parts like these. Ordering part by part can cost more than replacing an entire unit. Ask Andy if he has a refurbished unit?

A leaky pump (and your pipes look shot) may well induce more noise than is meant to be heard?

That pipe(s) should be replaced anyway as it really does look on its way out.

The pump does not require a lot of running time to bring he system up dependent on how low the pressure has dropped? We are talking a few seconds at a minimum.

So I just do not know the answer or even if there is one. My wife's X5 cost me in cash, time and effort as I ended up rebuilding the entire pump (having started by attempting to replace some parts). Then we found a leaky air bag and two faulty sensors. Many say that it would have been cheaper to rip it out and replace with Coil-overs. It probably would. But then I wanted to keep the car original.

 

[MangoMan]

Thanks Bruce....

I have sent the same photos to Andy so I'm sure he will advise accordingly. Does he do the Control Valve Assemblies aswell?

The most annoying thing is that I let my son have my "standby-car" so now now I'm Carlos on top of it. And to be honest I haven't got a bottomless pocket of money.

I did check the tops of the Air Springs but all good there.

We will just have to wait and see I suppose.

Cheers for now.

 

[MangoMan]

"Update"

Hi.

Not too sure if you will all agree but looking at the condition of the Pump when I stripped it today I do believe I have found the problem - or the major part of it.

Also, I'm sure the Filter was fitted the wrong way around. Surely the Airflow should show direction of Airflow...??? Photo shows how it was fitted.

I have asked Andy for a Cylinder and Ring Kit. And a new Filter and Pipe if he has them....

Enjoy!

Ciao.