Airmatic suspension problem on w205 C class C350e estate (2016)

[kam09]

I'm thinking it's a leak on my rear air bags or something happening with the struts.. Will be going on the ramp soon..

 

[rayasun]

I believe I have the same problem. When the car is parked for a few days without being used, both rear drops low. I have to manually press button to raise the car. There is no warning on the dashboard though. Mine has done 46k miles

 

[kam09]

I believe I have the same problem. When the car is parked for a few days without being used, both rear drops low. I have to manually press button to raise the car. There is no warning on the dashboard though. Mine has done 46k miles

Mine does have the "vehicle rising" message come up once engine is started.. however I'm using the car day to day..

 

[philnewmerc]

Mine had similar symptoms. It was the level sensor link. About 150 quid at the local specialist.

 

[Wheeker]

2016 C350e: Similar intermittant Airmatic issue- rear left corner drops randomly whilst parked, rear right corner as well, but not so much. It is very intermittant- away on holidays for 10days & return to airport car park- levels are fine. Yesterday park the car in the driveway & a few hours later the rear is down. When I start car get the "Vehicle is rising" message & the car is pumped up again & all is fine. I had a new MB compressor fitted by my indie MB mechanic in Jan '22, so my first instinct/hope is that perhaps the compressor pressure relief valve is faulty? But if this was the case would all 4 corners not be down? At least if this is the issue the MB compressor has a 2yr warranty(?) so hopefully the mechanic would get a free replacement, but would probably still charge for his labour. Maybe a Rear Left Air Bag leak, which is what the indie MB mechanic said over the phone, going on the info that it was that corner only- but then why would it happen intermittantly & not every time I park? Otherwise- valve block leak? Rear distribution block leak? Air line leak?

Is it best just to jack the car up, remove front left & rear left wheels, front left wheel arch liner & try leak testing as much as possible?

So I want to test the Valve Block- spraying with soapy water or disconnecting the compressor supply pipe to see if air is leaking back. However, I've read Arnott recommend swapping air lines on the valve block to see if the issue occurs on the same corner again (e.g. swap RL with FR). If it's same RL corner again then it's the airbag, if it moves to FR, then it's the valve block. Seems like a great diagnosis trick. However one video I watched the mechanic said don't do this if you're not using a scanner (I don't have one). Theory is- say RL goes down, car wants to pump it up but air goes into FR, which will overfill & burst the airbag. Will that really happen? Surely if I leave the car off it won't try to refill & corner will go down without car attempting refilling?

 

[PolishGeorge85]

So I want to test the Valve Block- spraying with soapy water or disconnecting the compressor supply pipe to see if air is leaking back. However, I've read Arnott recommend swapping air lines on the valve block to see if the issue occurs on the same corner again (e.g. swap RL with FR). If it's same RL corner again then it's the airbag, if it moves to FR, then it's the valve block. Seems like a great diagnosis trick. However one video I watched the mechanic said don't do this if you're not using a scanner (I don't have one). Theory is- say RL goes down, car wants to pump it up but air goes into FR, which will overfill & burst the airbag. Will that really happen? Surely if I leave the car off it won't try to refill & corner will go down without car attempting refilling?

Hi,
I'm not quite confident with swapping front/rear. As there maybe, or even I'm sure there are different setpoints/angels. Specially, having engine at the front.
Swapping left and right, definitely would indicate something. I'm not quite familiar with the system but swapping pipes can be done with any kind of "magic readers". If you decide to do it....run your car beforehand. Make sure car is at the right level. Measure distance from tire top to arch, or something like that. Maybe even ask someone to watch and make sure it doesn't go to high.

And, yes switching ignition OFF, kills compressor. It does however sometimes drop pressure from struts.

I would say.... something to do with wiring. 0 volts connection.

 

[PolishGeorge85]

Everyone says air struts, obviously it's possible. But looking on diagram (this is diagram with full air suspension) I would check pressure relief valve first. Like someone has mentioned after replacing compressor issues has cleared. I've just checked and this valve is mounted on the compressor chance why was replaced as well. If this valve is not closing correctly air will escape over time. And when engine is running it'll pump it back up.

Replying to the original post I would start with wiring/height sensor investigation. Controller could receive signal which it understood was correct height (even you car was slowly lowering)and for this reason wouldn't activate compressor to adjust it. And while you were driving with vibration eventually signal would go back to real value. That why message would appear on dash.

Relief valve I believe is still controlled for some time after ignition been switched off. That's why you can hear air coming out of somewhere. My car drops every now and then but not always. This could be relief valve no shutting correctly.

Regarding comment about wiring issues when there is no 0volts or 12v. When no voltage is applied to the valve, it stays closed. So in theory shouldn't drop.

But if you have two or more issues in the same time....my reply becomes absolutely useless

 

[Wheeker]

Just to give an update. My indie MB Mechanic ran a Star diagnostic for me & said compressor was fine. He advised that 9 times out of 10, if it's dropping on 1 corner only- it's the airbag. He quoted c. €750 for a genuine MB airbag & at least €250 in labour, so c. €1,000 in total. A lot of people advise to change both sides at the same time, as the other side is sure to fail soon enough. So that would be €1,750-€2,000. I just couldn't afford that & hard to justify throwing yet more money at my car.

So, after reading lots of forum posts & watching lots of Youtube videos, I concluded this could be a DIY job, so I took the plunge. I ordered RL & RR Airbags from Aerosus for €500 in total. On delivery, I realised they didn't come with the required retainer clips (despite saying they do on the website), so I ordered 2 of these from Miessler. The Aerosus airbags were supplied with airline fittings, but someone posted that they are tricky & best to use OEM (VOSS), so I also ordered 2x VOSS airline fittings & 3m of airline (just in case) from Miessler- €34 in total.

Installation:

• Removed Airmatic fuse & relay from under bonnet.
• Slightly loosened both rear wheel nuts
• Jacked-up car at Rear Diff & placed 2x jack stands & pads under each rear jacking point.
• Removed RL wheel
• Unclipped plastic protection cover from suspension arm
• Tried to remove bottom shock absorber bolt, but it was seized (I had even bought eTorx sockets especially for this)
• Very slowly unscrewed airline fitting from RL airbag, until all air out
• Easily managed to remove original airbag
• Removed original retainer nut & screwed on new retainer nut
• Realised that if I could compress & hold the new airbag, I could squeeze it in without removing bottom shock absorber bolt (used 3x cable-ties to compress & then cut once fitted)
• Took far too long to work out that the white plastic plug on the airline fitting should be removed before pushing on the airline!
• Tried to push-fit airline to Aerosus fitting but would not fit. So tried VOSS fitting instead, push-fitted perfectly first time
• Replaced plastic protection cover on suspension arm
• Replaced wheel
• Repeated on RR

Then came my mistake! I had read it is best to "prime" the new airbags with air before dropping the car, but I wasn't really sure how to do this without a special valve & air pressure line. In hindsight, perhaps if I had just replaced the Airmatic fuse & relay at this stage & turned on the ignition, perhaps it would have begun to fill the airbags? I had assumed, as it was jacked-up, the height sensors wouldn't tell the system to start the compressor. Anyhow, I removed the jack-stands & very slowly lowered the car. The car started to creep forward on the wheels of the floor-jack! Nearly had a heart attack! Anyhow, it was only about 2 feet & then it stopped. At the very least I should have put some bricks in front of the front wheels! Quickly replaced Airmatic fuse & relay & the airbags filled-up & lifted the rear off the trolleyjack! Looked like no damage to rear diff or exhaust- whew! That's it, I think it took me c. 2.5 hours in total. Car hasn't lowered again since (fingers crossed)! Prob saved myself €1,500.

FWIW- I inspected the original airbags by cutting off the rubber gaitors & then filling them with air from a bicycle pump. Sprayed them with leak detector spray & sure enough- the RL had 2x pinhole leaks. RR seemed airtight, but look at the photos, it was in a very poor state (185,000 km), so no doubt it would have failed at some point.

 

[PolishGeorge85]

You just made my day, not only didn't give up and let people rob your money. But also...You "sh.t" yourself, just when you thought you've ****.d something up...only to realise YOU DIDN'T....

WELL DONE