Air Suspension Problem

[IKV]

I have a W212 (2013 E Class Estate, AMG model) with about 80,000 miles on the clock. Over the past three months the self levelling air suspension on the rear of the vehicle has been collapsing overnight on an intermittent basis. Sometimes I will go out to the car in the morning and it needs to pump up before I can drive off, at other times there's no problem and I can get in and drive. Most times when the suspension has collapsed I get a warning message on the screen in front of me but occasionally I don't even though I can see the the suspension is down.

I took the vehicle into my local independent and they checked it over but couldn't find any leaks - they suggested that the standard fix is to replace the air springs for which they would charge £1,250. I'm pretty handy with the spanners and having checked a couple of videos, I reckon I can do the job but the parts (Pattern Parts made by Arnott) are still nearly £600 and I'm reluctant to spend that kind of money without some certainty of a result. My view is that if there is a leak in an airspring only one side would go down and if there is a leak in both then it wouldn't be an intermittent problem it would happen every time I parked. Incidentally I usually park on my driveway level ground.

So I'm looking for a common point in the system where there is a valve of some sort that maybe has a bit of dirt that is stopping it seating properly - is that a reasonable premise? Does anyone out there have any other ideas?

At the moment the system is pumping back up in a couple of minutes so it's not a problem but I can imagine that it is making the compressor work harder than it normally does and if that fails then I'm into much bigger expense.

Rgds Ian

 

[Weds]

Search the forum, there loads of post about this, mine was dropping overnight and slowly getting worse, couldn't find any leaks with soapy water, changed the airbags but still the same. Changed the solenoid but no change, changed the air lines and it stopped dropping overnight and been fine since. I would suggest changing the airlines first, it's the cheaper option...

 

[IKV]

Thanks for the reply Weds,
I've just spent a couple of hours underneath the car and checked everything with soapy water but there is no eveidence of any leakage. The airlines themselves look fairly bulletproof, on my vehicle they are just hard polythene lines, which are a push fit into brass nozzles at each end. There is one larger diameter feed from the pump to the valve and then two smaller ones from the valve to each airspring.
When you say you changed the solenoid, was that the device that I'm calling the valve with a single line going into it and two lines exiting. On my W212 it sits just in front of the rear bumper and behind the fuel tank. I guess it would be the easiest place to start replacing things because I can't find a leak in any of the lines.
Rgds Ian

 

[ChrisHGTV]

Search the forum, there loads of post about this, mine was dropping overnight and slowly getting worse, couldn't find any leaks with soapy water, changed the airbags but still the same. Changed the solenoid but no change, changed the air lines and it stopped dropping overnight and been fine since. I would suggest changing the airlines first, it's the cheaper option...

Having replaced everything on mine this is what I’d do first as well. Relatively cheap and there’s so much of the lines hidden you can’t be sure using soapy water anyway. I couldn’t even see the airline leak on mine even using the proper leak spray stuff.

 

[IKV]

That's two votes for changing the airlines first.

So, my next question is where best to source the relevant bits. I like the idea of just buying the airline in bulk and cutting to length to suit but will I need new brass fittings at each end as well? And, how do the lines fit into each connection. I have seen one online video where after unscrewing the old line, a new brass fitting is fitted into the airspring or valve unit and then the plastic pipe is a push fit into the brass fitting from whence it cannot be removed without destroying said fitting. Is that generally the case?

Any help would be gratefully received - or a link to an appropriate video.

Rgds Ian

 

[ChrisHGTV]

That's two votes for changing the airlines first.

So, my next question is where best to source the relevant bits. I like the idea of just buying the airline in bulk and cutting to length to suit but will I need new brass fittings at each end as well? And, how do the lines fit into each connection. I have seen one online video where after unscrewing the old line, a new brass fitting is fitted into the airspring or valve unit and then the plastic pipe is a push fit into the brass fitting from whence it cannot be removed without destroying said fitting. Is that generally the case?

Any help would be gratefully received - or a link to an appropriate video.

Rgds Ian

The lines are just push fit but you have to make sure you cut the ends perfectly square. I would say treat them as one use only to avoid any leaks. When i bought a new valve block from Autodoc i also bought a cutter - it was only a few £ from memory. Its a good idea to buy the airline and fittings separately as the official Merc part has an unnecessary brass connector on one side to join two sections of airline. But to me it makes sense to just have a full run. The brass connector itself isn't cheap either. One thing to note as well - the valve block and lines have colour markings so worth labelling which goes which before disassembling. The Merc Indy i used actually got it wrong which caused all kinds of problems. A second Indy corrected it! I ended up using Merc parts in the end apart from the valve block but from memory there were lots of sources of airline and fittings online. Might be worth trying Autodoc - i got the air bags and valve block from them - never had a problem with shipping etc. While you're looking at the suspension it's worth checking the plastic height sensor rods. One of mine had broken at one end. I got a replacement adjustable metal version from ebay.

 

[Weds]

Thanks for the reply Weds,

When you say you changed the solenoid, was that the device that I'm calling the valve with a single line going into it and two lines exiting. On my W212 it sits just in front of the rear bumper and behind the fuel tank. I guess it would be the easiest place to start replacing things because I can't find a leak in any of the lines.
Rgds Ian

Yes, valve/solenoid, the same thing sort of... I bought the lines from Mercedes, it was around £30 I think, but i seem to remember it came in sections the had to be joined together which was a bit strange, others may chip in about that..

 

[IKV]

So I have ordered new lines and connectors - the lines came from Hosemaster and are good for 250psi, the connectors are coming from Germany and are genuine Voss. But funnily enough, since I did my leak testing and removed and replaced the rear solenoid valve from its bracket so that I could clean all around it and check for leaks (as well as making a note of the part number) the car has behaved itself, it has stopped collapsing overnight. So I shall leave well alone until it starts misbehaving again, but it does seem that the issue is related to the airlines or maybe the valve.
Rgds Ian

 

[IKV]

So, to update this thread....

I replaced the valve block and all the lines, including the one from the compressor to the valve block. It made diddly squat difference to how the car behaved - sometimes the rear suspension would hold up overnight, or even for a whole weekend and then on other occasions it would be on its knees when I went to use it. So after searching around I found a company (Aerosus) who could supply the two rear airsprings for £244.80 delivered so I ordered a pair. They arrived a couple of days ago and yesterday I spent a morning fitting them and great stuff the car was still up in the air when I went to use it this morning so it appears to be a success. But.... I then thought I would do a bit of a check on the original MB units I removed, so I stripped off the outer dust shields and mounted them in a vice before inflating them off my compressor. I then searched for leaks and apart from a very tiny leak around the bottom steel clamping band on one of them - and I do mean tiny, there didn't appear to be anything wrong with them. So I'm still not sure what the original problem was.

However, just to comment on the quality of the units supplied by Aerosus, it would appear that the valves they are using are not genuine Voss items. As part of my previous exercise in replacing the lines and valve block, I bought a couple of genuine Voss valves to use on my existing units and they were pretty straightforward to connect - just make sure the end is cut off square and push it in. The Aerosus units were much more challenging and try as I might I couldn't just push the pipe in, even when I had slightly chamfered the end of the pipe. In the end I removed the valve and re-used my new Voss ones that I had extracted from the old units. Just a warning to anyone going down the same route.

Rgds Ian

 

[Wearsthefoxhat]

A bit late to this but is there a ride height sensor on the rear axle ?.
I had similar intermittent problems and mostly caused by a defective sensor and stiff control rod mechanism linkage.

 

[IKV]

Thanks for the response, Yes there are height sensors, one on each side but since they appear to be working (in that they notify me when the suspension has dropped and advise me to wait until it has reset itself before driving off) I have left them alone.
Rgds Ian

 

[Popell]

A bit late to this but is there a ride height sensor on the rear axle ?.
I had similar intermittent problems and mostly caused by a defective sensor and stiff control rod mechanism linkage.

I’ve replaced both rear bags with some pretty inexpensive replacements, seemed of but had various problems at the rear end including loss of wheel speed reading which turned out to be the reluctor rings, both now replaced, one of the arms that had moved on its bush and now the system is playing silly b****ars and I think it’s down to stiff links. They are so stiff in the rhs that it has bent and caused a fracture in the sensor mounting piece.
Recording a level sensor trace shows the lhs moving freely up and down as one would expect, while the rhs moves very little, perhaps a mm or two.
I know my level sensor is working, I just need to replace the linkage. Any ide of best place to source? Or if anyone knows the diameter of the ball joints I will make a replacement myself

 

[Wearsthefoxhat]

I’ve replaced both rear bags with some pretty inexpensive replacements, seemed of but had various problems at the rear end including loss of wheel speed reading which turned out to be the reluctor rings, both now replaced, one of the arms that had moved on its bush and now the system is playing silly b****ars and I think it’s down to stiff links. They are so stiff in the rhs that it has bent and caused a fracture in the sensor mounting piece.
Recording a level sensor trace shows the lhs moving freely up and down as one would expect, while the rhs moves very little, perhaps a mm or two.
I know my level sensor is working, I just need to replace the linkage. Any ide of best place to source? Or if anyone knows the diameter of the ball joints I will make a replacement myself

I bought mine from MB, only one at the rear of the S211.. expensive (£40 ish) for what it is but..

 

[Popell]

I bought mine from MB, only one at the rear of the S211.. expensive (£40 ish) for what it is but..

there are two on the 212, dealer gave a little discount but still 'spendy' at £185ish. Bit of a bitch to fit but cured my problem!
Pothole encounter cost a new front nearside spring the same week ...

Ironically the car was running beautifully after these fixes....it was at that point I decided to change the car so it got chopped in against a BMW 5 Touring so I have left the MB fold

 

[Petrol Pete]

Available pretty much everywhere , including MB obviously, A quick Ebay search is your friend.

⭐Mercedes E S212 W212 AWD Airmatic Luftfahrwerk Tieferlegung Koppelstangen V2 ⭐ | eBay

Gewindestangen/Muttern sind bei. -VA: Bis ca. 60mm Tieferlegung. -HA: Bis ca. 60mm Tieferlegung. -Modell: W212 (Allradantrieb). Luftfahrwerk Tieferlegungsset - Nur in Verbindung mit serienmäßigen Luftfahrwerk.

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