Still got issues on 2007 E class estate rear self levelling air suspension.

[Baldbloke]

The car is going into a tuning whizz for a fault code read and mot this coming Tuesday.
However, having driven it about 100 miles it appears to be sitting better and stopped blowing off air after shutting off engine.
Perhaps with all the components being renewed it has taken a while for the ECU to normalise the changes?

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[Baldbloke]

Ok. I took her into the tuning whizz who plugged his diagnostics kit into it followed by a remote laptop that was apparently Bluetoothed into it. Ran through a few programs including emptying the bags.... and it wouldn’t raise at all........
Then it became apparent there was a leak because you could hear a hissing noise above the compressor with the bonnet up.
Turns out with all the upping and downing a tiny split in the pipe has turned into an obvious bigger split and no air pressure is now reaching the back end.[emoji15]
The split is actually directly behind the shock absorber. Very strange.
So I’ve left the car at the garage and ordered metres of pneumatic 4mm pipe and 4 straight connectors in the hope this cures the issue once and for all. Once I get her home I’ll look at changing out the whole length.


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[Baldbloke]

So I put in a short joining section of pipe with two connectors and fired up the motor. 30 seconds later it was up and holding the correct ride height. MOTed and running fine.

Many, many thanks for the assistance! The crack in the air hose:

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[chrisk2010]

Glad you finally sorted it mate!

 

[andym2]

Great that it's fixed. You are now the S211 self levelling suspension expert!

 

[Borris1954]

Top marks for perseverance on getting this sorted.

I have been watching this thread with interest as I too am having sinking issues with the SLS suspension on the rear of my 2006 S211.

On two separate occasions I have had the rear go down. The drivers side seems to deflate first but if left long enough without starting the car the passenger side also goes down. It happened once in early March and again in late April but in between and ever since it stays up even if left for 5 or 6 days. I now have a bamboo cane marked with the "normal" left and right wheel arch height from the ground when the car is parked in its usual spot on the drive. This enables me to quickly check for any change each time I drive the car.

I guess I am going to be changing the air springs before too long. It's not clear to me if the issue is with the air bag itself or the solenoid valves not closing properly from time to time.

The key point is that this thread has given me the encouragement to have a go myself so thanks to all who have contributed.


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[Jkh112]

Glad it is fixed, thanks for posting the solution.

 

[Baldbloke]

Glad it is fixed, thanks for posting the solution.

I’m still not sure I’m an expert!
However, one of the two air bags was leaking, and because I ignored it for a while I think it cost me a compressor as it would have been working harder and longer.
The split in the pipe was a real mystery as it was about 300 mm from the compressor behind the front strut. The car did actually manage to raise itself well up after all the new bits were installed, so the crack obviously occurred with the new compressor in place. There was no rubbing and the pipe was well supported. It could have had a smaller crack in it that got larger with the diagnostics emptying and filling the bags but who knows[emoji3]


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[Baldbloke]

Top marks for perseverance on getting this sorted.

I have been watching this thread with interest as I too am having sinking issues with the SLS suspension on the rear of my 2006 S211.

On two separate occasions I have had the rear go down. The drivers side seems to deflate first but if left long enough without starting the car the passenger side also goes down. It happened once in early March and again in late April but in between and ever since it stays up even if left for 5 or 6 days. I now have a bamboo cane marked with the "normal" left and right wheel arch height from the ground when the car is parked in its usual spot on the drive. This enables me to quickly check for any change each time I drive the car.

I guess I am going to be changing the air springs before too long. It's not clear to me if the issue is with the air bag itself or the solenoid valves not closing properly from time to time.

The key point is that this thread has given me the encouragement to have a go myself so thanks to all who have contributed.


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Hi Borris. Is your car an estate/wagon too, or does it have Airmatic? Air just to the rear or on all four corners?


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[Borris1954]

Mine is an estate/wagon with SLS air suspension on the rears only. No airmatic.

I am just puzzled as to why it stays up most of the time (at the moment!). If an air bag was leaking then I would expect it to leak all the time so I am just wondering if sometimes a solenoid valve is letting air out. Anyway I guess its academic as the solenoid valve is part of the air bag/spring assembly.

I have now shown it the yellow card. The next time it goes down I shall replace both air/springs and take it from there.

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[Baldbloke]

Mine is an estate/wagon with SLS air suspension on the rears only. No airmatic.

I am just puzzled as to why it stays up most of the time (at the moment!). If an air bag was leaking then I would expect it to leak all the time so I am just wondering if sometimes a solenoid valve is letting air out. Anyway I guess its academic as the solenoid valve is part of the air bag/spring assembly.

I have now shown it the yellow card. The next time it goes down I shall replace both air/springs and take it from there.

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I could easily be wrong. But:

If it stays up on both sides for days it isn’t airbag leaks.
More likely to be a faulty bypass/blowoff valve in the compressor, or a small crack in the supply line.

Mine originally had an obvious leak on one rear corner. Put in new bags and it slowly came up. Three days later it totally came down while driven. Compressor goosed. Probably been working too hard and too long to compensate for the airbag losses. New compressor and relay and she came right up.

Briefly[emoji3]

Had I done what had been helpfully suggested and powered up the compressor without the engine I could have saved myself the trip for diagnostics as I probably would have heard the new leak in the pipe.
Perhaps the new compressor found a weak spot.

By the way. The valves at the airbags vent back through the line to the compressor and not at the bags themselves! Some aftermarket bags require the reuse of the valves with new seals.


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[Borris1954]

I could easily be wrong. But:

If it stays up on both sides for days it isn’t airbag leaks.
More likely to be a faulty bypass/blowoff valve in the compressor, or a small crack in the supply line.

Mine originally had an obvious leak on one rear corner. Put in new bags and it slowly came up. Three days later it totally came down while driven. Compressor goosed. Probably been working too hard and too long to compensate for the airbag losses. New compressor and relay and she came right up.

Briefly[emoji3]

Had I done what had been helpfully suggested and powered up the compressor without the engine I could have saved myself the trip for diagnostics as I probably would have heard the new leak in the pipe.
Perhaps the new compressor found a weak spot.

By the way. The valves at the airbags vent back through the line to the compressor and not at the bags themselves! Some aftermarket bags require the reuse of the valves with new seals.


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Thanks for taking the time to reply and giving some food for thought. It would be great if it was something much cheaper than needing to replace the air bags. I haven't used the car since Wednesday afternoon so it's been parked on the drive for over 3 days and hasn't dropped a millimetre.

What I don't understand yet is how the air could be getting out of the airbags when the car is parked up and the electronics have all gone to sleep. Surely it must either be escaping from the bag itself or leaking past the valves somehow and venting out through the compressor?

In my reading on the subject I am pretty sure I have seen other people describe similar symptoms to mine and been advised by experts such as @BlackC55 that is is most likely the air spring on it's way out. That said I'd hate to replace the air springs and find that wasn't the root cause...

Do you know if the air line from the compressor is pressurised all the time? I had rightly or wrongly assumed it was only when the compressor is running - otherwise how can the system vent air.

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[Baldbloke]

Thanks for taking the time to reply and giving some food for thought. It would be great if it was something much cheaper than needing to replace the air bags. I haven't used the car since Wednesday afternoon so it's been parked on the drive for over 3 days and hasn't dropped a millimetre.

What I don't understand yet is how the air could be getting out of the airbags when the car is parked up and the electronics have all gone to sleep. Surely it must either be escaping from the bag itself or leaking past the valves somehow and venting out through the compressor?

In my reading on the subject I am pretty sure I have seen other people describe similar symptoms to mine and been advised by experts such as @BlackC55 that is is most likely the air spring on it's way out. That said I'd hate to replace the air springs and find that wasn't the root cause...

Do you know if the air line from the compressor is pressurised all the time? I had rightly or wrongly assumed it was only when the compressor is running - otherwise how can the system vent air.

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BlackC55 is more than likely correct, but I would check everything else first.

Once I’d renewed the bags and before I’d sorted out the problems it only dumped air once the key was in the ignition and engine on.
I believe most compressors dump air to purge the lines so they don’t strain on restart. That shouldn’t mean that the bags dump air too, but mine did until all the issues were found and sorted. Mine was probably sending mixed messages because the split in the pipe couldn’t pressurise the system.
When I drove my car to get a diagnostic check the wheel arches were barely above the tops of the tyres. During the diagnostics the operator emptied the bags. It couldn’t then refill them to even the level I’d driven in with. So my final issue was that the split in the pipe had enlarged enough to not allow any pressure to enter the bags.

If I knew what I know now I’d firstly

1. Power up the compressor ( in situ) by disconnecting the lead and using a separate battery. This to see if it fills the bags and to listen for leaks. (That’s if the solenoid valves at the airbag tops allow air in). You only need to remove the near side front wheel and frontmost wheel arch cover to access it. A 20 minute job.

2. Flood the tops of the air bags with soapy water and squirting over the bases of the bags. Also over the splitter at the rear axle, and where the pipe work comes out of the inside of the car to look for bubbles.

3. If no leaks detected I’d take the compressor apart to look for piston ring/bore wear, and if dodgy replace or rebuild it. The £100 one I bought is slightly noisier than the original but just as efficient.

4. Replace the relay in the under bonnet fuse box. It’s only £13.00

Good luck and hope to hear the result of the job[emoji1303]

By the way if you need a new height level sensor I have a new one you can have cheaply.

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[Borris1954]

Thanks for the offer and I will PM you if I need a level sensor. At the moment I am hoping the car behaves itself until later in the year when I will have more time (and a garage to work in). But it's had it's final warning and if it miss behaves again it will be getting my undivided attention.

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[Baldbloke]

Thought I should at least post a photo of the end result[emoji3]

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[AndrewOl]

Mine is an estate/wagon with SLS air suspension on the rears only. No airmatic.

I am just puzzled as to why it stays up most of the time (at the moment!). If an air bag was leaking then I would expect it to leak all the time so I am just wondering if sometimes a solenoid valve is letting air out. Anyway I guess its academic as the solenoid valve is part of the air bag/spring assembly.

I have now shown it the yellow card. The next time it goes down I shall replace both air/springs and take it from there.

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My GL has sporadic air loss from the rear air spring. Pin hole was in the fold of the spring and it depended where the suspension settled as to if or how much it would drop. Changed bag and it’s been fine. Did for the compressor too but hey ho.

 

[Borris1954]

Thanks for your info. I think the failure mode you describe is exactly what I have and reading more on the old interweb it seems to be quite common. Looks like I need to firm up plans to replace both air bags asap and refurb the compressor for good measure.

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[Borris1954]

Thanks for your info. I think the failure mode you describe is exactly what I have and reading more on the old interweb it seems to be quite common. Looks like I need to firm up plans to replace both air bags asap and refurb the compressor for good measure.

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Latest update on this is from me that the car was finally red carded after the rear suspension sank yet again on the OSR. As I now have a copy of Star I ran the compressor test which failed with an indicated likely fault in the valve body (which I don't have as its not full airmatic) or a number of other causes including leaking solenoid valves. Apparently the rear raised itself during the test which it's not supposed to! As I have bought in a pair of Arnott replacement bags I started to follow the WIS instruction to replace the offside one first. However, I had to abort as even though I had deflated the bag I couldn't get it out. I notice the Arnott video shows a lot more of the suspension being removed than in WIS which just has the tie rod being disconnected and the retaining bolt at the bottom of the spring being removed. Have others had this issue?

With hindsight I don't think I deflated the spring correctly. I think I should have compressed the spring whilst deflating it and then let the Star close the solenoid valve?. I think I had an extended spring with air at atmospheric pressure which I was trying to compress to get it out.

 

[Borris1954]

A late posting to clarify my posting above. I have to hang my head in RTFM failure shame and own up to not "turning the page" of my WIS instructions for deflating the air springs with Star. It's actually a 2 step process and I only did step 1!

Step one you use Star to open the solenoid and release most of the pressure through the compressor's valve. Step two is to then remove the airline from the spring and then again use Star to open the solenoid on the spring. Loads more air comes out and the spring length shrinks so it's then easy to get out.

Confession over.

PS Getting the airline undone without the MB special tool was a bit of a nightmare struggle until I sacrificed a 10mm deep reach socket by angle grinding a slot along its length so I could slide it over the airline and onto the the connectors nut and then undo with pliers.

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[Baldbloke]

Latest update on this is from me that the car was finally red carded after the rear suspension sank yet again on the OSR. As I now have a copy of Star I ran the compressor test which failed with an indicated likely fault in the valve body (which I don't have as its not full airmatic) or a number of other causes including leaking solenoid valves. Apparently the rear raised itself during the test which it's not supposed to! As I have bought in a pair of Arnott replacement bags I started to follow the WIS instruction to replace the offside one first. However, I had to abort as even though I had deflated the bag I couldn't get it out. I notice the Arnott video shows a lot more of the suspension being removed than in WIS which just has the tie rod being disconnected and the retaining bolt at the bottom of the spring being removed. Have others had this issue?

With hindsight I don't think I deflated the spring correctly. I think I should have compressed the spring whilst deflating it and then let the Star close the solenoid valve?. I think I had an extended spring with air at atmospheric pressure which I was trying to compress to get it out.

Just read this so apologies for late reply.
I seem to remember that I too had to remove quite a bit of the suspension to remove the air bags as i had a similar issue, and no diagnostics to help. Just removing the airline connections did not release all the air. It wasn't until I'd removed the three screws holding the valve in place that the bags fully depressurised.