W211 rear suspension drops sometimes but not always

[2006e280]

Hi, I have a 2006 w211 e280 estate with rear self-levelling suspension. When parked, the rear suspension often drops right down over a 24-48 hour period. What's weird is that it doesn't happen all the time - if it doesn't drop I can leave it for weeks and it won't drop at all.

I'm pretty certain that it has never dropped after a long journey with stuff in the boot - as long as I park it and leave it. If I stop, unload the stuff and then move it to park it, it's far more likely to drop.

I've taken it to my local 'MB specialist' independent garage and they put it on a diagnostic system - no errors - and checked the air lines and bags - no leaks. They're telling me it's going to be very costly to fix and I may have to do both sides. I don't mind spending a few hundred quid to fix it - but the car's worth less then £4k so I don't want to spend too much!

This feels to me like an electronic fault so I'm not convinced that replacing the entire rear suspension is the best / only way to fix it.

If anyone has any suggestions as to where I could point my local garage, or knows of someone in the South West who could look at it for me I'd love to hear.

Thanks

 

[phobos]

looks like a height sensor is on its way out. did the indepent checked the height sensors / arms as with the age of the car they can seize?

 

[AntMB]

Air suspension, the triggers broom!

 

[2006e280]

Thanks phobos… I don’t think they did. I left it with them for three days and it didn’t drop, even though they repeatedly moved it and parked it in different places. It was they who suggested the solution was to replace the entire units, potentially on both sides - I thought there must be a better solution, hence my post. I’ll try an alternative dealer and ask them to check the height sensors - thanks!

 

[m80]

I'm interested in this in case our 211 shows the same issue,
our 639 has rear air suspension and that was dropping occasionally on one side, it seems to have resolved itself, fingers crossed.

But in my mind it 'aint the market value of the car that would determine the plausibility of a repair. Our S211 isn't worth lots but I would spend a fair amount to keep it right. The car suits our needs, aside from being a bit retro inside. It would be difficult to beat it w/o spending many £,000's. Not that I'm saying you spend lots on the suggested trial and error.

 

[AntMB]

I'm interested in this in case our 211 shows the same issue,
our 639 has rear air suspension and that was dropping occasionally on one side, it seems to have resolved itself, fingers crossed.

But in my mind it 'aint the market value of the car that would determine the plausibility of a repair. Our S211 isn't worth lots but I would spend a fair amount to keep it right. The car suits our needs, aside from being a bit retro inside. It would be difficult to beat it w/o spending many £,000's. Not that I'm saying you spend lots on the suggested trial and error.

Rather than face a triggers broom incident after spending some time and money on my 211, I ditched the air suspension.

 

[m80]

Rather than face a triggers broom incident after spending some time and money on my 211, I ditched the air suspension.

How does it ride in comparison?
I'm impressed with ours. I've been in other large cars that are crashy by comparison.

 

[AntMB]

How does it ride in comparison?
I'm impressed with ours. I've been in other large cars that are crashy by comparison.

Don't honestly feel any difference.

It's a 2003 car that I've had 5 years, I'm not spending air suspension money on it, so it was either this or nothing.

 

[merc85]

Could be a porous alloy tank where the hose goes over.

 

[pretzelmeister]

Does it drop on one side or both? Airline from compressor is T-ed at the back, and there is just the one height sensor.
If dropping on one side only, then could be a pinhole leak in the air strut bellows. Drops will be 'random'. Pinhole will be covered most times by the bellows concertina, but not at others.
If both sides dropping, then highly unlikely is bellows - chances of them both failing at the same time and exposing pinhole leaks at same time is slim, i'd've thought. So more likley issue common to both sides - height senor, T-piece. Not compressor nor airline - as I gather rises / rides level when engine (& compressor) running - and only drops when parked?
I had 1 side dropping intermittently on my 2007 W211 estate. When I bought the car, one of the rear springs had already been replaced, the other was original. Car started sagging on one side only.
After 3 different garages, I eventually decided to replace the original spring. 4 months on, car hasn't dropped since.
Replaced it with an Arnott A-2726 - c. £230 delivered from AutoDoc - after garage said was fine to replace just the one, even though Arnott clearly state must be repkaced in pairs.
So after the one Arnott was fitted - ride height was fine - but kepy getting self-levelling suspension warning on the dash - which wound-up the missus,
So had the other side replaced as well - which turned out to be a Bilstein (KLF-7663).
So - only if sagging on the 1 side - suggest you try to find out what air springs you have on already - and if the side that isn't sagging isn't original, then replace the side that is sagging with spring from same manufacturer.
However, if non-sagging side is original, then you have wider choice of spring - but suggest you don't go down the Arnott route - unless you fancy replcing both just for fun.

 

[2006e280]

looks like a height sensor is on its way out. did the indepent checked the height sensors / arms as with the age of the car they can seize?

Just wanted to let you know that you were right - replaced the sensor and arm, all now fine. It was straightforward and cost less than £300 from my local indy MB garage. Car doesn’t drop at all and drives perfectly. Thanks!

 

[phobos]

Just wanted to let you know that you were right - replaced the sensor and arm, all now fine. It was straightforward and cost less than £300 from my local indy MB garage. Car doesn’t drop at all and drives perfectly. Thanks!

no worries, glad to help!

 

[Pontoneer]

Hi, I have a 2006 w211 e280 estate with rear self-levelling suspension. When parked, the rear suspension often drops right down over a 24-48 hour period. What's weird is that it doesn't happen all the time - if it doesn't drop I can leave it for weeks and it won't drop at all.

I'm pretty certain that it has never dropped after a long journey with stuff in the boot - as long as I park it and leave it. If I stop, unload the stuff and then move it to park it, it's far more likely to drop.

I've taken it to my local 'MB specialist' independent garage and they put it on a diagnostic system - no errors - and checked the air lines and bags - no leaks. They're telling me it's going to be very costly to fix and I may have to do both sides. I don't mind spending a few hundred quid to fix it - but the car's worth less then £4k so I don't want to spend too much!

This feels to me like an electronic fault so I'm not convinced that replacing the entire rear suspension is the best / only way to fix it.

If anyone has any suggestions as to where I could point my local garage, or knows of someone in the South West who could look at it for me I'd love to hear.

Thanks

Isn't the S211 the same hydropneumatic system as used on W123 and W124 estates ?

If so , there are no electronics involved : the system is purely mechanical .

You will have a reservoir with ZHM mineral oil in the engine compartment , an engine driven high pressure pump and a hydraulic line to the level control valve which is fixed to the underbody and linked to the rear anti-roll bar , this senses the level and either allows more fluid to be pumped to the struts if the car is too low , or to return to the reservoir if it is too high . The fluid also passes through one side of a 'sphere' , one on each side of the car ; the spheres have a diaphragm with nitrogen gas on one side and the mineral oil on the other side ; since gas can be compressed and fluid cannot , this gives you your springing and shock absorption and the struts control the ride height ( the struts are not shock absorbers as some people mistakenly believe ) .

While some people are in awe of the hydropneumatic system , it really is very simple and actually quite reliable , with the most common faults being corroded hydraulic pipes under the car leading to fluid loss ( and consequent damage to the pump if it runs dry , which is an expensive item ) , burst diaphragms in the spheres , which leads to a very hard ride , or the height control valve which can either lose its small link rod to the anti-roll bar , leading to loss of control , or the drop link can come loose at the anti-roll bar end , giving false readings ( the sometimes works , sometimes doesn't makes that a good place to start , i think ) also the valves themselves can fail , but this is less common and one of my cars got to almost half a million miles with the hydropneumatic suspension still working .

This system was used on every W123 and W124 estate , not sure about the later ones , was also used in W126 and W201 as an option ; and of course it was widely used by Citroen and Rolls-Royce .

 

[Pontoneer]

Don't honestly feel any difference.

It's a 2003 car that I've had 5 years, I'm not spending air suspension money on it, so it was either this or nothing.

One of my friends had a Subaru Legacy estate that went the same way , and he converted it to standard springs and shocks , drove fine .

 

[Pontoneer]

Does it drop on one side or both? Airline from compressor is T-ed at the back, and there is just the one height sensor.
If dropping on one side only, then could be a pinhole leak in the air strut bellows. Drops will be 'random'. Pinhole will be covered most times by the bellows concertina, but not at others.
If both sides dropping, then highly unlikely is bellows - chances of them both failing at the same time and exposing pinhole leaks at same time is slim, i'd've thought. So more likley issue common to both sides - height senor, T-piece. Not compressor nor airline - as I gather rises / rides level when engine (& compressor) running - and only drops when parked?
I had 1 side dropping intermittently on my 2007 W211 estate. When I bought the car, one of the rear springs had already been replaced, the other was original. Car started sagging on one side only.
After 3 different garages, I eventually decided to replace the original spring. 4 months on, car hasn't dropped since.
Replaced it with an Arnott A-2726 - c. £230 delivered from AutoDoc - after garage said was fine to replace just the one, even though Arnott clearly state must be repkaced in pairs.
So after the one Arnott was fitted - ride height was fine - but kepy getting self-levelling suspension warning on the dash - which wound-up the missus,
So had the other side replaced as well - which turned out to be a Bilstein (KLF-7663).
So - only if sagging on the 1 side - suggest you try to find out what air springs you have on already - and if the side that isn't sagging isn't original, then replace the side that is sagging with spring from same manufacturer.
However, if non-sagging side is original, then you have wider choice of spring - but suggest you don't go down the Arnott route - unless you fancy replcing both just for fun.

So these do run on air rather than hydropneumatics - can't help wondering why they replaced a reliable system with an unreliable one .

One of my neighbours had a W220 S500L with air , he ended up replacing all four corners at a cost of £2000 per corner , each time he said that meant keeping the car another year , though he did eventually sell it , and currently runs a W211 saloon . Another friend with a W220 S320 also had air suspension problems , with the rear dropping randomly and a noisy compressor which sounded like it was under the drivers footwell ... that one was a cheap car and was just sold on the way it was . W220 air suspension problems seem commonplace ; hydropneumatic suspension is both reliable and easy to maintain .