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Discussion Starter #1 (Edited)
When reading through various threads after my car’s airmatic suspension pump failed, I discovered that some members of the forum raised questions regarding the scheduled maintenance interval on the air filter of the pump. I quote:
“Anyone know the scheduled maintenance interval on the air filter? I don't see any mention of it in the Service Sheet, nor could I find the repair instructions for it in WIS.”
“Just wait and replace it along with the relay when the pump goes bad.”
“Assuming the filter is much cheaper than the pump, why not replace it? Perhaps it will greatly extend the life of the pump.”
“I found my filter was in a poor state with debris in both ends - looks like someone had connected it the wrong way around at the last fix.”
“…you won’t get a warning until the debris from the unfiltered air starts clogging up the system!”
“One oddity: My car did not have an air filter leading to the pump, and as the previous pump had lasted over 200k without one I have not installed one.”

My MB dealer recommended that I should also replace the relay and the 40A fuse as mentioned in the installation sheet that came with the pump. Nothing was said about the filter. Why bother?

The part number of the pump filter is 220 320 00 69. Some catalogues list it as “Air Filter, compressor intake.” It is cheap and fairly straight forward to replace the filter. One simply has to pull the filter and its rubber housing out of its mount point, loosen the clamp, fit the new filter in the rubber housing and push it back.

I was horrified when I removed this filter and saw its condition. It was clogged with debris in both ends, and the filter element inside was hard and loose. It makes a clunking sound when you shake it. It has an awful burnt scent. When I tried to blow it from both sides, I discovered that the movement of the loose filter could block the flow of air. The attached pictures illustrate it’s poor state.

I have found it difficult to get reliable information about the functioning and the scheduled maintenance interval on the air filter. It seems that the hose of the pump draws air from above the mount point of the filter (it is mounted upside down on the frame aft underneath the wiper fluid and coolant reservoirs). This area is well protected from the elements.

The other end of the filter is connected to the hose of the pump. Valotus pointed out that this particular hose is not a high pressure hose: “…it comes from purge valve and is connected to air intake hose by T-junction without any valves. When the compressor pumps, there is a slight vacuum in that hose as purge valve is closed and compressor takes air in from filter. When pressure is reduced from springs, compressor stops and purge valve conducts exhaust air back to filter through that hose.” This explains why my filter (and the filter of one of the members which I quoted) has debris in both ends.

Could a clogged air filter cause the fuse to blow? I quote Valotus: “If there exists any air pressure in that hose when compressor runs, it means that purge valve is faulty and opened for some reason. It certainly causes compressor to run extended time as it can't produce enough pressure, and therefore finally may blow fuse.” My theory: a clogged filter could cause air pressure in the hose and might contribute towards the chain reaction which Valotus described.

Although it would only be possible to proof this theory by means of experimental verification (who is going to take the risk?), I came to the conclusion that it makes good sense to replace the filter. It costs only $10, and it would not take more than 20 minutes to replace. After paying quite a large sum to replace both front struts (last year) and the airmatic compressor (the past week), it would be foolish to risk this investment by exposing the compressor to a clogged intake and outlet.

The photos show the new OEM part and different angles from both the old and the new filters. The debris on both sides of the old filter is clearly visible (Edit - it appeared as debris before I dissected the filter - please read on).

Daniel
 

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2003 SL500, 2012 E350 4Matic P2
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Daniel,

Great writeup. I looked as you did and can not find any reference to a maintenance schedule for the pump filter.

The WIS says.............


When I pulled my pump down to change out the valve block, I changed my filter but did not find it clogged as yours was. I replaced mine at 105K miles.

Bob
 

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........I was horrified when I removed this filter and saw its condition. It was clogged with debris in both ends, and the filter element inside was hard and loose. It makes a clunking sound when you shake it. It has an awful burnt scent. When I tried to blow it from both sides, I discovered that the movement of the loose filter could block the flow of air......l

What was first - chicken or egg?

The burnt scent may be a result of the burned motor and the smoke which comes with that fault. Incoming (smoke) and outgoing air goes through the filter (part a in the picture).
 

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Discussion Starter #4 (Edited)
Thank you very much for your comments, Bob and Bullethead. I value your contributions as very important.

Bob's finding that his filter was not clogged could be reassuring to many owners. He mentions that he changed his valve block. I assume that his pump wasn't seized or burned as in my case.

The diagram which Bullethead attached and his observation that incoming and outgoing air goes through the filter confirms the explanation of Valotus. When one looks at the pictures of both ends of the clogged filter, the difference in colour confirms his conclusion that the burnt scent may be a result of the burned motor and the smoke which came as a consequence of it. The one end of my filter is black (obviously caused by smoke coming from the pump) (Edit: I was wrong. Please read on).The other end is brown (Edit: I discovered it was the rusted bottom side of the filter element after I had dissected the filter).

It seems that the filter should indeed be replaced after the motor burned or seized.

Daniel
 

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Is it possible that broken hose between compressor and filter cause failure of airmatic compressor?
 

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Discussion Starter #6 (Edited)
I am not a technician. My response is therefore based on reasoning and not on experience.

The compressor is located very close to the front of the vehicle, behind the air inlet grate of the lower bumper section. A broken hose would expose the compressor unfiltered air, debris and the elements. It could damage the compressor as well as the valves and cause failure.

I would welcome the input from more experienced members as I regard this as a very relevant question. MB changed the design of the intake line. With the new pump, the line fitting is now on the opposite side (closer to the electrical connections). That means the original rubber hose which connects the filter to the pump line is too short. A member of the forum advised that one should buy a longer rubber hose which is a lot cheaper than buying the previous problematic intake line (it seems that it was more prone to leaks). The obvious choice would be to use a fuel hose which I would not recommend (It has a thicker wall than the original hose and is therefore not as flexible. The vibration of the pump could therefore cause more friction on the rubber housing of the filter, damage the grommet and cause the filter to pop out of its mount point). Or one could opt for an inferior hose that could shave through if it is not fitted properly.

I would recommend a good quality hose with a 2mm wall that is able to withstand the wind and the elements. Friction against the right front engine compartment panelling and other parts should be eliminated.

Daniel
 

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Is it possible that broken hose between compressor and filter cause failure of airmatic compressor?
It will cause failure sooner or later. At least piston ring and cylinder will be scratched so that compressor can't rise pressure anymore.

Original flexible rubber hose between filter and compressor intake seems often to be cracked and faulty. And if it goes broken, it's like you don't have filter at all.

Air intake filter is there for only one reason; to prevent any dirt particles ending up into system. For same reason are oil filters, fuel filter, engine air intake filter, etc. All of these filters are meant to be replaced (or cleaned in some cases) after certain time, so why would this be an exception.

The original airmatic filter is Mann WK 32/6, which is a common paper element fuel/air filter. It costs couple of dollars or euros, even if bought from MB dealer.
 

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Discussion Starter #8
The anatomy of the airmatic filter

A broken hose exposes the compressor as well as the other parts of the airmatic system to dirt particles. It will cause failure sooner or later, as Valetus pointed out. it's like you don't have filter at all.

A loose filter element could also expose the system to dirt particles. When dissecting my old airmatic filter, I discovered that it had been inoperative because the filter element had become loose of the small plastic tube on which it is mounted. This caused the clunking noise (I mentioned this in a previous post) when I shook it.

One of the attached pictures show the top half of the plastic housing with a small tube. The intake of the filter element is mounted on this tube (it literally hangs on it). When I pressed it back on its mounting, I had to use force to get it loose again. It remains a mystery how it became loose inside the plastic housing. Could this be a design flaw? The consequence: the air which entered the filter bypassed the filter element.

I also discovered that some of my previous findings were wrong. The filter wasn't clogged with debris. The brown "debris" which I saw at the one end was actually the rust on the closed end of the filter. The "black" colour on the other side was also not "debris" that was caused my smoke as I assumed. It was the open or intake end of the filter which seemed black because it led to the inside of the filter. One photo shows that the inside of the filter has the same colour as the outside. I therefore have to offer my sincere apologies: my conclusions before I dissected the filter were completely wrong!

However, the results of the dissection has turned out to be more alarming. The filter element had become loose of its mounting inside the plastic housing, which meant that the intake air bypassed the filter element. My compressor had therefore been exposed to dust particles which entered the aft. Although this location is more sheltered that a broken hose, we all know that dust finds it way...

Daniel
 

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I've been repairing my defective compressors lately and living in the rust belt I find the inside of the compressor crank region to be lightly coated in salt residue. The filter works great on solids, but stinks when it comes to dissolved solids. Any suggestions on how to stop the salt water from going right through the paper filter?
 

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Discussion Starter #10
I would suggest that one should find the entry point of water.

The hose of the pump draws air from above the mount point of the filter (it fits into a rubber grommet (part number 2203280279) that is mounted upside down on the frame aft underneath the wiper fluid and coolant reservoirs). This area is well protected from the elements. It is unlikely that water could enter from there unless the grommet is punctured or water from a leaking reservoir is dripping from the upper part of the frame aft into the intake tube. I have not inspected the mounting area of the grommet, but I assume that the engineers would have considered preventative measures in this regard.

Water could also enter through a broken or leaking hose. The compressor is located right behind the air inlet grate of the lower bumper section and is therefore exposed to rain and snow.

I noticed that you had read the thread of Valotus regarding the water content in the the desiccant of the compressor. When he opened his 2004 compressor, he discovered the dryer unit was soaking wet. You mentioned in that thread that you have been doing a lot of reading about the various desiccants (You know much more about compressors than me!). I assume therefore that the salt residue is something completely different, also because you refer to the crank region of the compressor.

If the preventative measures of the engineers fail to prevent water from entering the filter in your region, I would suggest designing and installing a drip tray. It could save you a lot of trouble and money.

Daniel
 

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Any tell tales?

A broken hose exposes the compressor as well as the other parts of the airmatic system to dirt particles. It will cause failure sooner or later, as Valetus pointed out. it's like you don't have filter at all.

A loose filter element could also expose the system to dirt particles. When dissecting my old airmatic filter, I discovered that it had been inoperative because the filter element had become loose of the small plastic tube on which it is mounted. This caused the clunking noise (I mentioned this in a previous post) when I shook it.

One of the attached pictures show the top half of the plastic housing with a small tube. The intake of the filter element is mounted on this tube (it literally hangs on it). When I pressed it back on its mounting, I had to use force to get it loose again. It remains a mystery how it became loose inside the plastic housing. Could this be a design flaw? The consequence: the air which entered the filter bypassed the filter element.

I also discovered that some of my previous findings were wrong. The filter wasn't clogged with debris. The brown "debris" which I saw at the one end was actually the rust on the closed end of the filter. The "black" colour on the other side was also not "debris" that was caused my smoke as I assumed. It was the open or intake end of the filter which seemed black because it led to the inside of the filter. One photo shows that the inside of the filter has the same colour as the outside. I therefore have to offer my sincere apologies: my conclusions before I dissected the filter were completely wrong!

However, the results of the dissection has turned out to be more alarming. The filter element had become loose of its mounting inside the plastic housing, which meant that the intake air bypassed the filter element. My compressor had therefore been exposed to dust particles which entered the aft. Although this location is more sheltered that a broken hose, we all know that dust finds it way...

Daniel

Daniel, I appreciate your resolve in tracking this FAIL. Question, before you dissected the filter housing, did the filter rattle inside the housing?

The appearance might indicate that the filter had processed little air given the age of the part.

As it was loose, perhaps the filter was shocked loose at some time early in its life by a front end collision? The simple compression fitting in the design could lend its self to shock or even temperature differential allowing the filter to sweat loose. What's your best guess?:confused:
 

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Discussion Starter #12 (Edited)
Asureyes, Thank you for responding.

It did rattle before I dissected it as reported in #1 and in the previous thread "Symptoms of a seized airmatic pump".

The attached picture shows some dirt particles against the inside wall of the lower section of the plastic housing. It indicates that contaminated air bypassed the filter. Also visible in the picture are the extending ribs at the bottom on which the filter element rested after it had become loose. I think it was designed this way to prevent blockage if the filter element might become loose.

The previous owner assured me that the car had not been damaged in an accident. However, I do remember that the workshop manager asked me if it had been involved in an accident because the front parts seemed to be new (the car is still in an excellent condition). I would not exclude some kind of shock because the workshop manager also pointed that the splash guards of the wheel hubs were damaged (picture). It seems that the car might have hit the ground with the front wheels removed (perhaps an accident in the workshop?).

I am in no position to speculate over temperature differential allowing the filter to sweat loose. My gut feeling rules it out because that should not happen with a Mercedes Benz part. I think the engineers did consider that metal and plastic expand and contract differently when the temperature changes rapidly. Maybe they allowed too much room for the filter element to expand.

Daniel
 

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My old filter had inner parts loose too. It was from -04 E270 and never changed as far as I know.

I guess MB (or Wabco as manufacturer) had chosen this filter model just for its dimensions and inlet/outlet diameters. That's because arrow on the side of filter shows direction of flow as it was originally designed. In this case, when filter is correctly installed, it's upside down and arrow shows towards the air flow.

However, it may not be a big deal with air volumes of this system.
 

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Discussion Starter #14 (Edited)
According to the WIS (AR32.22-P-2001I), "the arrow on the air filter (2) must point towards the longitudinal member", which refers to the rubber grommet (see the illustration).

I bought a VW fuel filter and decided to dissect it as well. It is a FRAM G4705. The MB airmatic filter is six times (600%) more expensive than the FRAM filter. I compared all the dimensions and came to the conclusion that they are almost identical.
a. Both filters use the same filter element.
b. The inner construction is identical.
c. The outer dimensions of the plastic housing are identical.

The only differences as far as I can see are
d. the MB airmatic filter has a lip on its outer housing where the rubber grommet is fitted.
e. The tube of the airmatic filter to which the arrow points has an external diameter of 8mm and the fuel filter 10mm.

The pictures are attached.

Daniel
 

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Discussion Starter #15 (Edited)
My conclusion

I have waited for someone else to draw a conclusion, but it seems that I have to do it. I do not think that part number 220 320 00 69 was designed for the airmatic suspension system. It seems to be a fuel filter that is being used the wrong way around. That is why it becomes loose. If one should consider to use it in accordance to the direction of flow as it was originally designed, then it would not fit in its mounting place. It would also expose the metal part of the filter element to the elements which could cause rapid corrosion, especially in the salt belt.

I shall communicate my conclusion to MB in Germany, and suggest that they should consider to design a new air filter for the airmatic suspension system. It simply does not make sense to risk exposing very expensive equipment to the elements by using a filter that was not originally designed for its function in the system (BTW the VW version sells for $2 in South Africa).

Daniel
 

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Discussion Starter #16
Update of my letter to Daimler AG in Germany

I shall communicate my conclusion to MB in Germany, and suggest that they should consider to design a new air filter for the airmatic suspension system. It simply does not make sense to risk exposing very expensive equipment to the elements by using a filter that was not originally designed for its function in the system.
I addressed my letter to Mr. Jochen Haab, the Manager of Technical Support of Daimler AG in Germany. I sent it on 27-03-2017. The letter is attached.

Daimler AG responded on 07-04-2014 informing me that Mr. Jochen Haab isn`t the responsible person for my request. They forwarded his response to me (I can read German) and requested: "Please tell us the name of another Person." Could Bullethead or any other member help, please?

Daimler AG also forwarded my letter to Mercedes-Benz South Africa. They kindly asked me to bear with them until such time they have more accurate information pertaining to my enquiry.

I am glad to report that my letter has been received in a good spirit.

Daniel
 

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..... Could Bullethead or any other member help, please?....
I don't know a special responsible person. In case someone send a letter to Stuttgart MB will forward it to their customer assistance center in NL-Maastricht.

DaimlerChrysler Customer Assistance Center N.V.
P.O. Box 1456
NL-6229 EN Maastricht

This center has been established for european customers.
 

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Discussion Starter #18
Thank you, Bullethead. That is also what Jochen Haab suggested to [email protected]:
Ich möchte Sie bitten, diese Anfrage entweder an den Fachbereich Achsen / Federung (RD/FC) oder aber an einen Kollegen im Bereich GSP/TPC bzw. das CAC in Maastricht offiziell zur Bearbeitung weiter zu leiten (bitte mit dem Vermerk, dass ich nicht zuständig bin).
Daniel
 

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Recently I met an old man on the street who has pre-facelift W220. We chatted and I asked whether he had any airmatic issues. He said that he repairs his car himself and every winter he changes Airmatic air filter which is full of salt (in this country salt is used on roads in winter).

While the guy has not read this thread, the folk-culture at least in salty countries rule that airmatic air filter _is_ serviceable part. As well as changing fuel filter before and after every winter.
 
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