S212 Rear Suspension Dropping

[steveq]

Hi,

Last week I bought an 2011 S212 E220 CDI Estate. I previously had an S211 E220 CDI Estate for over 8 years and it was great.

I noticed a problem with the rear air suspension on my new car. It sags down when parked overnight. It looks like it is right down as far as it can go when it is left for 24 hours.
When I turn on the ignition i the morning there is a display saying 'Please wait - vehicle rising'.
After 1 -2 minutes the car is back up to normal level and the message clears.

I attached my iCarsoft i980 to the car and it reports 'C156884 The right rear vehicle level is outside the tolerance. There is a signal below plausible level'. It also gives the same error for the left (the error number is C156684).
It also reports:
Left 7mm B22 2549 mV/7 Left rear level sensor
Right 13mm B22 2412 mV/10 Right rear level sensor

I am planning to get underneath over the weekend to see if I can see any damage or leaks on the pipework.

Any suggestions?

Thanks,
Steve

 

[Steve@Avantgarde]

Either be a leak somewhere or the airsprings are failing.

Cant see it being anything else.

 

[wilsodg]

There was a problem with the self levelling - can't remember what does this but some had leaks. Mine were replaced under warranty after 9 months. Same vintage as yours and symptoms. Expensive if you have to pay I fear.️


Sent from my iPhone using Tapatalk

 

[steveq]

Hi,

Thanks for your posts.
I haven't had a chance to get under it yet -- poor weather, busy time of the year, etc., and it isn't actually broken (yet).

All tips and hints on where to look and how to spot a leak are very welcome,

I'll update when I know more.
Thanks,
Steve

 

[AMck]

Hi,

Thanks for your posts.
I haven't had a chance to get under it yet -- poor weather, busy time of the year, etc., and it isn't actually broken (yet).

I would say it us broken as it is dropping so quickly. As said probably a leak which means the pump is having to work more to keep pumping it up and keeping up with the leak. If left it is likely to lead to earlier failure of the pump. Unfortunately leaving it until it completely fails is what a lot of people do, thus making the repair more expensive in the long run. I've had two Range Rovers with air suspension and on the forums ignoring early signs of leaks was all too common leading to more expensive repairs and the air suspension being labelled unreliable. Sometimes all it would have needed was a 10p O ring, but ends up with £500 for a pump.

 

[AMck]

Sorry, meant to say to detect leaks at joins use some soapy water - it will blow bubbles if leaking.

 

[steveq]

Hi,

I put the back of the car up on blocks and got underneath. I can see a valve block attached to chassis close to the back bumper. It has one larger tube and two smaller tubes. I assume the larger tube is from the pump and the smaller tubes are to each suspension bag.
No sign of leaks from there and the pipes look like they are in good condition.
The tubes to/from the valve block route under plastic covers.
I assume that it is unlikely that there is a break or crack under the covers as they are well protected from the elements. I can see pipes emerging right beside the suspension and going towards the top of the bag. It is impossible to see the connection to the top of the bag without some dismantling.

The nearside seems to sag faster than the offside. Possibly the leak is only on the nearside and the offside is being effected by the nearside leak.

As an aside, the previous owner got a towbar fitted some time ago. It looks like a neat job and probably not relevant to the suspension dropping although the towbar is quite close to the valve block.

Thanks,
Steve

 

[steveq]

Hi,

I put the back of the car up on blocks and got underneath. I can see a valve block attached to chassis close to the back bumper. It has one larger tube and two smaller tubes. I assume the larger tube is from the pump and the smaller tubes are to each suspension bag.
No sign of leaks from there and the pipes look like they are in good condition.
The tubes to/from the valve block route under plastic covers.
I assume that it is unlikely that there is a break or crack under the covers as they are well protected from the elements. I can see pipes emerging right beside the suspension and going towards the top of the bag. It is impossible to see the connection to the top of the bag without some dismantling.

The nearside seems to sag faster than the offside. Possibly the leak is only on the nearside and the offside is being effected by the nearside leak.

As an aside, the previous owner got a towbar fitted some time ago. It looks like a neat job and probably not relevant to the suspension dropping although the towbar is quite close to the valve block.

Thanks,
Steve

 

[steveq]

Hi,

I tried the soapy water bubble test on the connections at the valve block underneath the bumper and at the top of the suspension bag on the nearside (the side that sags more).
No sign of any air leaks at any of the joins.

I think the next step is to purchase new air suspension units for the left and right and fit them.
The S212 has different air suspension units compared to the S211 and are slightly cheaper.

Steve

 

[steveq]

Bought and fitted air suspension bellows

An update:-

I purchased new suspension units for both left and right sides.

I started the job to fit the left side yesterday.

The car hadn't been used for a coupe of days so the rear was right down with the wheels under the wheel arches.
I could just fit a trolley jack under the rear jacking point.
With the other 3 wheels suitably chocked I jacked up the car and removed the wheel (and placed an axle stand under a rear subframe mounting point).

The first task was to remove the air line to the suspension unit. It is difficult to get an open spanner onto it. I cut a little tooth sized bit out of the plastic surround using a small sharp wire cutters. That allowed me to get the spanner onto the brass nut and loosened. There was a hiss of air when I removed the air line -- not much as most of the air had already escaped.

I could lever the top and bottom off their seating but there was still no way to get the unit out.
I then removed the nut holding the tie-rod to the torsion bar on the basis that it was holding the suspension up. With that removed the axle moved down an inch or more.
Using a large screwdriver I was able to lever the base up out of the seating in the lower suspension arm and then pull down the top and wriggle it out between the flexible brake line and the body.
Halfway there and not too much hassle I thought.
I thought that was the difficult step.

 

[steveq]

Fitting the new suspension bellows

I tried to get the new unit into the space.
It was possible to get it between the shock absorber and the brake line by pushing it through horizontally but there was no way to turn it vertically to get it into the lower suspension unit well or into the upper fitting. I tried it top first and bottom first but to no avail.
It was possible to pull down the suspension to increase the gap but no matter how much I tried I couldn't pull it down enough.

Eventually, I removed the bolt holding the shock absorber to the lower suspension arm (remove the plastic cover from the arm to get at the bolt). That allowed some more space but still not enough.
I removed the large bolt holding the lower suspension to the axle (this was very tight and I needed a breaker bar to loosen it).
I levered the lower suspension arm down (it is a very tight fit so remained in place even after the bolt was removed).
That allowed plenty of room to get the new unit in place. Once into the lower well there was an inch or more space at the top. I actually pushed it up into the top fitting where it hung. I could then check that the bottom of the unit was slotting into the suspension arm well by stretching my arm in as I lowered the car.

I connected up the air line by simply pushing the air line into the new unit as far as it would go.

I then put the lower shock absorber bolt back in and levered the lower suspension arm back into place and put the bolt back in.
I then reconnected the tie-rod and the torsion bar.

I refitted the wheel and lowered the car slightly to be at the approximately correct height but kept the weight of the car on the jack (or course I removed the axle stands.
I started the car and let it idle for a while.
I then lowered the jack and the car stayed at the correct height.
Success -- well it is too early to tell.
I left the car overnight and it was definitely lower this morning but not by much (about an inch) which was a bit disappointing.
I brought it for a drive today and it drove fine.
I'll keep an eye on it over the next few days.
The right side still has to be done -- it never dropped as bad as the left side used to anyway.
The next week will tell a lot.

 

[malcolm E53 AMG]

Thanks for the detailed 'how to do it' info no doubt a lot of S212 drivers like myself will be interested in how you get on

Good luck with it!

Ps where did you go for parts are they from MB?

 

[steveq]

Hi,

I identified 3 suppliers (excluding Mercedes):- Arnott, Aerosus and Miessler. There are the above suppliers plus others on eBay too.

I struggled to get a price from Arnott -- they won't sell direct and sent me to a distributor. I contacted them and they won't deal directly but pushed me towards a local (and very good) motor factors - that was all to just get a price. I decided that was too long a chain and would end up being expensive anyway with all the mark-ups added along the way.
Miessler would not have the left side in stock for 6 weeks which I decided was too long to wait.
The above narrowed it down to one and I bought the Aerosus units. I ordered from their UK site but they came from Germany and they arrived very quickly.

I fitted the left side unit last weekend. The jury is out as to whether the problem is solved or not. I won't be using the car for a few days and I want to see how well it stays up.

I am sure there are lots of jokes about drooping after a short time; how long it will stay up; an extra inch making all the difference, etc., etc. but this is much too polite and serious a forum for that kind of nonsense !!?

It really is just a matter of removing 3 bolts (torsion bar/tie rod; bottom bolt of the shock and the big bolt between the suspension arm and the hub) to get the old one out and fit the new -- actually the old one came out without removing the shock bolt or the suspension arm bolt but the new one won't go in with removing those.
OK - There is also the little brass nut for the air supply too but that is just too obvious.

 

[steveq]

Fitted right hsnd side suspension

I fitted the right hand side unit yesterday.

The car was unused for a week and the RHS had dropped down completely.
It dropped more slowly than the LHS, which dropped overnight (before I changed it), but still after 6 days it was completely down.

I was a bit quicker doing the job this time. I found that I needed to remove the tie-rod completely to be able to move the base of the shock absorber to allow the suspension unit through the gap between it and the brake pipe.

The airline would not go into the unit as deep as it was in the old unit. On the old unit it was in as far as the paint mark on the pipe. It is about half an inch further out of the unit -- It seems to be airtight though.

I had some difficulty reattaching the tie-rod to the torsion bar. I ended up reattaching it after I had the wheel back on and the car lowered when the bar was under less tension.

The suspension rose when I started the car and brought it for a run. It is still at the correct height now after almost 24 hours.

It is a DIY job that can be undertaken on the driveway but it is also a bit fiddly (removing the plastic cover from the lower suspension), hard to see (lower suspension bolt removal and refitting) and frustrating (getting the unit past the brake line and into its seat).

 

[steveq]

It is now almost a week since I fitted the second unit.
I didn't use car for the first few days and it remained up at the correct height. My driveway is on a slope going down from left to right. It self levelled correctly so that there is a slightly larger gap at the top of the right wheel and the rear is perfectly level.
When I did use it and parked on a level surface for the day it maintained the same height on both sides.

I am suspicious that the rear suspension is slightly firmer now with the new units -- that could easily be me being over-sensitive though.

The bottom line is that the original issue is now resolved

 

[David Selfe]

Bought and fitted air suspension bellows

An update:-

I purchased new suspension units for both left and right sides.

I started the job to fit the left side yesterday.

The car hadn't been used for a coupe of days so the rear was right down with the wheels under the wheel arches.
I could just fit a trolley jack under the rear jacking point.
With the other 3 wheels suitably chocked I jacked up the car and removed the wheel (and placed an axle stand under a rear subframe mounting point).

The first task was to remove the air line to the suspension unit. It is difficult to get an open spanner onto it. I cut a little tooth sized bit out of the plastic surround using a small sharp wire cutters. That allowed me to get the spanner onto the brass nut and loosened. There was a hiss of air when I removed the air line -- not much as most of the air had already escaped.

I could lever the top and bottom off their seating but there was still no way to get the unit out.
I then removed the nut holding the tie-rod to the torsion bar on the basis that it was holding the suspension up. With that removed the axle moved down an inch or more.
Using a large screwdriver I was able to lever the base up out of the seating in the lower suspension arm and then pull down the top and wriggle it out between the flexible brake line and the body.
Halfway there and not too much hassle I thought.
I thought that was the difficult step.

Hi Steveq,
I’m new to this site however like you I have the same car and seemingly the same issue.
The near side rear drops over night but the offside stays at the right height. I’ve tried different parking positions but always the near side drops down. No error messages on the dash or on odb reader, and the car raises very quickly when the ignition is on.
I’m wondering, and would appreciate your input, whether you think it could be the bellow? And if I’m replacing one side should I change both like you did?
Regs,
D

 

[steveq]

Hi and welcome,

I suggest that you look for leaks in the air lines to the near side unit. If only that side is dropping it might be a leaking pipe. Use soapy water along the pipe and at the valve block which is under the rear bumper on the S212.
If it is a leaking suspension unit you could probably replace one side if you bought a MB unit. However, I would suggest they are replaced in pairs - they are both the same age so the other is likely to fail soon and if you use a non-MB unit it will have different characteristics to the other side.
Doing nothing isn't an option either as the pump will burn out due to over use.
Best of luck with it.

 

[David Selfe]

Thanks for the quick reply and the advice. I plan on getting the car in the air and having a good look around. Like you I have already thought about replacing both sides if the bellow is leaking and whilst I’m at it probably change the shocks. Planning on fitting a towbar for towing, so if I’m doing the bellows makes sense to do the shocks at the same time.

 

[stevem9]

Have just done the RHS on my 2012 S212 and was an easy job, remove trim in load space (only the forward one, two clips at the back edge - pull out the centre pin to release, remove the screw in the plastic fitting near the front - you can see it in the top and the panel will unclip, there is one plastic clip hidden inside which pops out eventually) and undo two top shock absorber mount bolts. Remove the plastic tray from the bottom arm, just squeeze the retaining clips and push through and remove the bolt through the bottom of the shock and take it off. Using a 10mm open ended slim spanner you can undo the airline from the spring, it's a bit of a fiddle and you only get a small turn a time but once you've got about a couple of rotations it becomes finger tight. Use a hammer and drift to unseat the spring from the bottom arm, it may be pretty tight, mine needed a club hammer, and a pair of pry bars to release the top. The old unit will now come out easily through the gap made by removal of the shock. If for any reason it is too long to easily fit you can suck the air out with a vacuum cleaner and an air bed adapter, this is what we did with the new unit just to make it a bit easier to get in. Fitting is the reverse, just make sure it seats properly at the bottom then the top (cleaning the bottom cup and a spray with silicone or PTFE helps) then lower onto the suspension arm with an axle stand underneath and guide the top in. Total time about 3/4 hour

 

[sub2hours]

I know this is an old thread but replaced my air springs on Sunday with Aerosus units. Took a while to arrive and then ended up having to pay import fees on UPS despite the Aerosus site saying everything is included. To be fair, Aerosus refunded the import fees within a day so happy with them.

The car, 2011 S212 E220 was fine when the air temp was above 10-12 degrees but any cold nights would see the rear drop fully. It would usually stay up for a few hours.

I decided to remove the shock absorber on each side and this made access much easier. Tricky bits were undoing the brass nut for the air hose removal. Probably took me about 3 hours for both sides at a leisurely pace.

The car no longer drops but we haven't seen any really cold nights yet. Last night was 6 degress and all fine.

The picture below shows the condition of the replaced units.