S211 Self leveling suspension troubleshooting

[Bogo]

Hi Folks,

I am trying to find some sort of troubleshooting guide for self leveling suspension issue. Could you point me to the right direction?
The rear of the car goes all the way down overnight, usually during the day it stays up fine.
In the morning I get a warning - stop, car level to low, it needs ¬30 seconds to get it back to correct level.

Looks like its either one of the rear airbags fault or a pipe leak.

Have you any suggestions where to start?

 

[LostKiwi]

Airbag leak is in the money. Soapy water sprayed around the bags and pipework should help you find where.

 

[Bogo]

I got following error code on my diagnostic tool
5152 rear level sensor incorrect signal
I'll try to do soapy water method and check sensor connections at same time.

 

[LostKiwi]

I got following error code on my diagnostic tool
5152 rear level sensor incorrect signal
I'll try to do soapy water method and check sensor connections at same time.

The link arm to the sensor can rust and break.

 

[Bogo]

The link arm to the sensor can rust and break.

Checked rear level sensor this evening and all seems to be fine. Sprayed some soapy water over pipework and airbags and no bubbles at all. Why during the day and some night car would stay up and on other night rear would drop completely?

 

[malcolm E53 AMG]

We are seeing a lot of S211 rear air suspension problems on the forum now that these cars are >10 years old most are due to worn out rear airbags which are better changed in pairs. Worth doing a search on 211 airbags as one or two members have done a diy

 

[Bogo]

We are seeing a lot of S211 rear air suspension problems on the forum now that these cars are >10 years old most are due to worn out rear airbags which are better changed in pairs. Worth doing a search on 211 airbags as one or two members have done a diy

cheers for that, was searching for "self-leveling" before with very few results

 

[bembo449]

that's probably cos folks put " suspension fault " as thread starter and not a specific one to their actual problem pal

 

[Oldspanners]

Hi Folks,

I am trying to find some sort of troubleshooting guide for self leveling suspension issue. Could you point me to the right direction?
The rear of the car goes all the way down overnight, usually during the day it stays up fine.
In the morning I get a warning - stop, car level to low, it needs ¬30 seconds to get it back to correct level.

Looks like its either one of the rear airbags fault or a pipe leak.

Have you any suggestions where to start?

I used a gas leak detector spray as it is a lot stickier than just soapy water and shows up even a small leak. The air bag was leaking around the electrical connector and was difficult to see. Changed both in about two hours after that all's been well in over a year.
Followed this video advice doesn't seem to be expert but what he is showing is correct, I only needed to remove two bolts. You may not have the reservoirs and won't have to worry about cutting the old hoses away if you are fitting new ones without them as well.

 

[Bogo]

I used a gas leak detector spray as it is a lot stickier than just soapy water and shows up even a small leak. The air bag was leaking around the electrical connector and was difficult to see. Changed both in about two hours after that all's been well in over a year.
Followed this video advice doesn't seem to be expert but what he is showing is correct, I only needed to remove two bolts. You may not have the reservoirs and won't have to worry about cutting the old hoses away if you are fitting new ones without them as well.

Much appreciated; this morning rear didn't go down, if its airbag wouldn't it be more constant? not like now fine one night, fine during the day and than all the way down next night; I'll park it in exact spot for next couple of days and monitor.

 

[Oldspanners]

Much appreciated; this morning rear didn't go down, if its airbag wouldn't it be more constant? not like now fine one night, fine during the day and than all the way down next night; I'll park it in exact spot for next couple of days and monitor.

It depends where the leak is in the airbag, if it's in a fold and under compression it may not leak and the the next time when it's not it will.
Of course it may not be an airbag but a valve or line until you find the leak it's just guessing.

 

[malcolm E53 AMG]

It depends where the leak is in the airbag, if it's in a fold and under compression it may not leak and the the next time when it's not it will.
Of course it may not be an airbag but a valve or line until you find the leak it's just guessing.

Totally agree this is where the maxim ‘they all do that sir’ can be used, problem airbags do tend to leak intermittently at first and you’ll find this mentioned throughout most threads on the subject.

 

[Uncle Benz]

Leaks on the bags themselves are harder to find because Mercedes encase the bellows inside a flexible plastic outer. Other manufacturers have the rubber parts on show, and spotting the problem is often much easier. I have seen plenty of cars that sink every night, but after being lifted right off the ground on my lift and resettled don't sink for four or five days. The leaking part of the bellows must end up in a slightly different place.

 

[Bogo]

Thanks lads; what's the risk of leaving it as is until spring? I don't drive much and have a second car too, so it wouldn't be end of world if it doesn't level at all one morning.
According to my research leaks affect compressor, so the costs of fixing could be a lot higher.

 

[malcolm E53 AMG]

You could do that but I wouldn’t recommend it you’ll wear or burn your compressor out as long duty cycles of 2+mins keeping the system pressurised don’t do it any good. Air compressors are relatively crude devices and soon build up excessive heat if over used as there is no cylinder cooling

 

[Uncle Benz]

You could do that but I wouldn’t recommend it you’ll wear or burn your compressor out as long duty cycles of 2+mins keeping the system pressurised don’t do it any good. Air compressors are relatively crude devices and soon build up excessive heat if over used as there is no cylinder cooling

This. The compressor has a plastic piston running in an aluminium barrel. Excessive running will wear it out.

 

[Bogo]

compressor need only ¬30s to get back up, never heard it while driving; is it located under rear row of seats?

 

[Andyn666]

It's located behind the front bumper on the passenger side

 

[LostKiwi]

And just because you can't hear it doesn't mean it's not running...

 

[Bogo]

And just because you can't hear it doesn't mean it's not running...

fair enough, if its under bumper there is a good chance that I wont hear it; anyway parked in exact same spot for last two nights and... no issue, cant believe its coincident