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

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Baldbloke

Active Member
Joined
Apr 8, 2016
Messages
542
Location
Moray
Car
E Class Estate 320CDI Elegance 2007 Non- ADS
A couple of days ago I changed out the rear (non-ADS) air suspension bags. All was good as the car immediately came up and sat correctly, and it drove well without issues until my wife took it to work;). Today the message came up on the Command screen that the car was too low, and right enough, on arriving where she'd stopped at the roadside, the car was equally down at the back on both sides.
Drove it home and jacked it up to find the new air bags were fine and holding considerable pressure, but obviously not quite enough to sit up correctly.
I did notice after fitting the new air bags two days ago that there was a noticeable dump of air when I jacked the suspension back up to check all was well after a test drive. Presumably this was because the suspension was hanging down and giving the ride height sensor a false indication that the car was sitting too high, and needing to lose some pressure.
Now my wife heard a noise just before the fault message came up. She said it wasn't a pop as if a bag had exploded but sounded like air being released......
I have now taken the inner splash guards off from the nearside inner wheel arch and found the compressor and filter. I note one thin airline coming from the compressor heading rearwards through the wheel arch into the passenger compartment. Could this be where the valve block is that I heard operating after jacking up the car two days ago, and could this be the issue?

Is the valve block contained within the compressor or is it seperate, if this is a common failure, and how to check it please?
Or is it a case of replacing it anyway as it's cheap enough to not warrant fannying around?
 
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A couple of days ago I changed out the rear (non-ADS) air suspension bags. All was good as the car immediately came up and sat correctly, and it drove well without issues until my wife took it to work;). Today the message came up on the Command screen that the car was too low, and right enough, on arriving where she'd stopped at the roadside, the car was equally down at the back on both sides.
Drove it home and jacked it up to find the new air bags were fine and holding considerable pressure, but obviously not quite enough to sit up correctly.
I did notice after fitting the new air bags two days ago that there was a noticeable dump of air when I jacked the suspension back up to check all was well after a test drive. Presumably this was because the suspension was hanging down and giving the ride height sensor a false indication that the car was sitting too high, and needing to lose some pressure.
Now my wife heard a noise just before the fault message came up. She said it wasn't a pop as if a bag had exploded but sounded like air being released......
I have now taken the inner splash guards off from the nearside inner wheel arch and found the compressor and filter. I note one thin airline coming from the compressor heading rearwards through the wheel arch into the passenger compartment. Could this be where the valve block is that I heard operating after jacking up the car two days ago, and could this be the issue?

Is the valve block contained within the compressor or is it seperate, if this is a common failure, and how to check it please?
Or is it a case of replacing it anyway as it's cheap enough to not warrant fannying around?

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Am I stripping out the passenger footwell unnecessarily?



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Sorry to keep bugging you guys but my nearest dealers with Star are both 50 miles away. Aberdeen and Inverness so not handy. I can't actually find anything that looks like a valve block until the rear axle. Is there actually such a thing as a valve block on a Non ADS estate car with self levelling to the rear only?
There's a junction box above the rear suspension where the supply feed pipe joins in and another two pipes go either side to each rear air bag, but that is it as far as I can see.
I'm not familiar with compressors but am now wondering if any air regulation happens via the height regulator (which is less than a year old) on the rear torsion/anti roll bar, and the compressor itself? Does the compressor allow air out (to lower the ride height) as well as giving air to compensate for extra weight in the back of the estate car?
 
Hi fella sorry I know nothing about this stuff but try this link it'll take you to exploded parts diagrams maybe you'd be able to trace it with those.

click on catalogues you should only need your vin number.

Search for parts. Buying auto parts around the world. Auto parts catalogs.

Sorry if it isn't helpful.

Cheers Chris, any input gladly received. Will check it out on a desktop computer rather than my phone.[emoji1303]


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Hi Baldbloke been looking for about half and hour and drawing a blank for the E Class but the S class looks like it's located at the front passenger side looks like just behind the bumper somewhere.

Level Control Valve Block
The valve block unit (Y36/6) is located near the air suspension compressor. In the case of the W220 S-Class, it is located on the right side, between the passenger side headlight and the air suspension compressor. The valve block contains valves which open and close to direct the air pressure that is sent to each air sturt. The air is feed from the air suspension compressor or the air reservoir.

You are being redirected...
 
Number 160 in the picture if it's a W211

View attachment 84945

Thanks Chris.
Not sure if my self levelling rear suspension even has a valve block as there’s only a single air line from the compressor going to the rear of the car where it divides in a splitter box with a line going to each rear air suspension bag. My thoughts are that there must be an air dump/ release valve at or near the compressor.
I’m planning to remove and check the compressor tomorrow as well as get the part no off it. If it’s suspect and I can find a reasonably priced replacement I’ll possibly just change it out along with the relay and filter. Then everything will have been renewed with the exception of the lines themselves. Just have to find where the relay lives.
I have actually just today had to buy a replacement vehicle as was so stuck. The Mercedes is too good to scrap though, and hopefully I’ll get it running properly with a bit more time. Just a bugger there’s no one nearby that I know of with the correct diagnostics.


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There is no valve block if you've only got the air springs on the back for SLS.

The release valves are built into the air springs, so I suspect your new air springs might have a small rupture.

From the first post, it sounds like you fitted the new springs and didn't inflate them before taking the car off the jack stands?

This can lead to them puncturing. I've done the same thing with a brand new bilstein air spring that cost me £279 so I feel your pain!

I found out the hard way the correct installation process is to position the air spring without tightening the bottom bolt, inflate to 0.5 bar to make the bag rigid (I jumped the relay for a few seconds), then make sure it's parallel to the shock absorber. The bilstein units come with a fitting aid for this. Them tighten the bolt to 150nm. Then jump the relay again to inflate the bag properly. Then lower the car till the rear wheel just touches the ground and let the carbide for 5 mins before finally putting it back on the ground.

There is a video on YouTube put up by bilstein showing all of the above.

Hope that helps.
 
There is no valve block if you've only got the air springs on the back for SLS.

The release valves are built into the air springs, so I suspect your new air springs might have a small rupture.

From the first post, it sounds like you fitted the new springs and didn't inflate them before taking the car off the jack stands?

This can lead to them puncturing. I've done the same thing with a brand new bilstein air spring that cost me £279 so I feel your pain!

I found out the hard way the correct installation process is to position the air spring without tightening the bottom bolt, inflate to 0.5 bar to make the bag rigid (I jumped the relay for a few seconds), then make sure it's parallel to the shock absorber. The bilstein units come with a fitting aid for this. Them tighten the bolt to 150nm. Then jump the relay again to inflate the bag properly. Then lower the car till the rear wheel just touches the ground and let the carbide for 5 mins before finally putting it back on the ground.

There is a video on YouTube put up by bilstein showing all of the above.

Hope that helps.

Cheers Millo, thanks for your replies.

The bags are still inflated equally after two days in the workshop but obviously not enough to give a satisfactory ride height. They also align parallel to the shock absorbers without actually touching them. With this in mind I don’t believe they are punctured. I think it’s either a knackered /intermittent pump issue, a relay, or a problem with the sensor on the rear antiroll bar. My issue is that the bags equally lowered inexplicably while the car was being driven by my wife, which to me indicates that air was asked to be dumped for some reason. The bags were still hard and remain hard with air pressure.

When I installed them the suspension was unloaded so the pump/ compressor obviously though the ride height indicated air was not required. Once the car had weight on the wheels the pump filled both bags to the correct ride height within two minutes from empty. The car then drove without fault for two days before suddenly having a tantrum [emoji3]


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The relay for the compressor is in the fuse box under the bonnet. In my car its right at the back, closest to the windscreen and the outside of the car. Genuine mb ones are green and are about £13 from the dealer.

You can test the compressor by jumping the sockets for pins 87 and 30 which should turn the compressor on even without the ignition on.

Compressors are straight forward to rebuild. An eBay seller called bagpipingandy sells a good kit for about £20. Check the cylinder head for scoring as that may need to be replaced if it's heavily scored and can be bought from eBay for about £30.

It's also worth replacing the dessicant material in the compressor, and definitely replace the filter.

Perfectly serviceable aftermarket compressors are available on eBay for about £100 though.

If you do take the compressor out, be very careful refitting it.

The frame it mounts to is quite flimsy and its easy to snap the studs the compressor fits onto.

I've done that as well.

The revised part is a lot beefier, but needs new fitting kits for the compressor , so the new frame and fitting kit came to £91 from the dealer.

You have to take the front bumper off and remove the passenger side headlight to fit it . That was a fun day. Not difficult jobs, but a pita none the less.
 
Sounds like it must be ride height sensor then? It's fixed to the rear anti roll bar. The small bar connecting the sensor to the ARB may have come loose? That's where I'd start if everything else is in order.
 
Cheers Millo, thanks for your replies.

The bags are still inflated equally after two days in the workshop but obviously not enough to give a satisfactory ride height. They also align parallel to the shock absorbers without actually touching them. With this in mind I don’t believe they are punctured. I think it’s either a knackered /intermittent pump issue, a relay, or a problem with the sensor on the rear antiroll bar. My issue is that the bags equally lowered inexplicably while the car was being driven by my wife, which to me indicates that air was asked to be dumped for some reason. The bags were still hard and remain hard with air pressure.

When I installed them the suspension was unloaded so the pump/ compressor obviously though the ride height indicated air was not required. Once the car had weight on the wheels the pump filled both bags to the correct ride height within two minutes from empty. The car then drove without fault for two days before suddenly having a tantrum [emoji3]


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A faulty compressor wouldn't cause the air springs to deflate.

The release valve for the deflation is built into the air spring. They will only deflate if the sensor triggers them to, or they leak.

In fact, to get my original air springs off I had to drill a hole in each of them to get them deflated enough to remove! Even after disconnecting the air hose they won't let any air out.

I'd start by checking jumping the compressor relay to make sure that works. When it pumps back up you can investigate the level sensor and whether there are any leaks.

For what it's worth, I had similar symptoms from the new one I installed incorrectly. The car drove fine for a couple of weeks then the spring deflated.

Hopefully it will just be the connector between the level sensor and the ARB though.
 
A faulty compressor wouldn't cause the air springs to deflate.

The release valve for the deflation is built into the air spring. They will only deflate if the sensor triggers them to, or they leak.

In fact, to get my original air springs off I had to drill a hole in each of them to get them deflated enough to remove! Even after disconnecting the air hose they won't let any air out.

I'd start by checking jumping the compressor relay to make sure that works. When it pumps back up you can investigate the level sensor and whether there are any leaks.

For what it's worth, I had similar symptoms from the new one I installed incorrectly. The car drove fine for a couple of weeks then the spring deflated.

Hopefully it will just be the connector between the level sensor and the ARB though.

All very helpful thanks[emoji1303]. I’ll hopefully give it a look tomorrow and report back.
One thing I will mention that I’d never heard before is that on fitting the new bags, driving it and taking it back to the workshop there was an audible release of air from the front of the car when I jacked up the car to check the air bags were still properly in situ. I presume that by unloading the suspension the ride height sensor decided less air pressure was needed and dumped some to compensate.
Also that there’s nowhere on the non-ADS valve (that sits on top of the air bag)to allow a release of air UNLESS it’s via the airline that feeds the spring. IE back down the small diameter feed pipe that sits at the top of the air spring. Remember the air springs in my car only operate at the back and that they have NO alloy air reservoir. So, a different system to Airmatic.
Thanks again for your input.


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My car is the same set up with air springs only on the back for the self levelling function.

When the springs release pressure it does vent back through the compressor. From what I've read, it's supposed to go back through the dessicant chamber to help dry it out before it exits.

Since fitting a new compressor my car now has a pressure release from the compeessor whenever I turn the car off. It seems like when the car is running the compressor is primed with preasure and when turned off it releases the excess pressure with a whoosh.
 
Well when the car went down at the back with your wife driving the ride height sensor must be right at the top of culprits to cause this,it is just a potentiometer ,if that is damaged or has moved then ride height will go up or down,as you say it is 50 miles to a indy,have a ring around local garages one may have a star ,I found a local garage which quiet frankly I would never have used but was told they had a star and knew how to use it.
 
My car is the same set up with air springs only on the back for the self levelling function.

When the springs release pressure it does vent back through the compressor. From what I've read, it's supposed to go back through the dessicant chamber to help dry it out before it exits.

Since fitting a new compressor my car now has a pressure release from the compeessor whenever I turn the car off. It seems like when the car is running the compressor is primed with preasure and when turned off it releases the excess pressure with a whoosh.

Cheers for that Millo. That would explain why deaf me thought he heard a whoosh from the front soon after replacing the air bags at the rear after jacking it back up.


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