2004 Mercedes E320 CDI Rear Air Suspension Issue

Mar64

Member
Joined
Jun 11, 2020
Messages
10
Reaction score
0
Your Mercedes
2004 Mercedes E320 CDI
Hi, I've got a 2004 Mercedes E320 CDI estate and have an intermittent rear air suspension problem.

The rear air suspension on both sides will drop at the same time. Always with the car parked and usually happens overnight, although the suspension will occassionally stay up for up to 3 days!!! I mistakenly took it to a Mercedes specialist who assured me it was the valve body and compressor. So I had these replaced and it's still exactly the same.

However I've noticed that if I disconnect the battery then the car does not go down at all, which suggests that it's an electrical issue.

So if it's an electrical issue where would be the obvious places to start looking in order to try and resolve this issue?

Thanks,
Mark
 

alexanderfoti

MBO Forum Supporter
Authorised Forum Supporter
Joined
Mar 25, 2010
Messages
15,165
Reaction score
6,352
Location
Tonbridge
Your Mercedes
W221 S65 AMG - W204 C63 AMG + Various other MB's
Most of the time its the rear air bags leaking, or the tanks inside the rear subframe.

Easy to check the valve body, spray the lot with leak detection fluid and see if its leaking! Should be very much clear cut. Compressors don't cause leaks though.....
 
OP
M

Mar64

Member
Joined
Jun 11, 2020
Messages
10
Reaction score
0
Your Mercedes
2004 Mercedes E320 CDI
  • Thread Starter
  • Thread starter
  • #3
Thanks for the reply.

The car is not going down when the battery is disconnected. So I assume from that, that it's not a leak but some electrical issue on the car.
 

alexanderfoti

MBO Forum Supporter
Authorised Forum Supporter
Joined
Mar 25, 2010
Messages
15,165
Reaction score
6,352
Location
Tonbridge
Your Mercedes
W221 S65 AMG - W204 C63 AMG + Various other MB's
Does it do this every time, in different locations? Bags often don't leak if parked in a certain way etc......

if 100% then its likely that the car is waking up periodically and trying to level itself. If it has keyless, could be the handles waking it up, if not then 100 other things potentially.
 

sidmon

Senior Member
Joined
May 14, 2007
Messages
170
Reaction score
6
Location
Midlands
Your Mercedes
Mercedes 190E 1989 2.0
Hi, I've got a 2004 Mercedes E320 CDI estate and have an intermittent rear air suspension problem.

The rear air suspension on both sides will drop at the same time. Always with the car parked and usually happens overnight, although the suspension will occassionally stay up for up to 3 days!!! I mistakenly took it to a Mercedes specialist who assured me it was the valve body and compressor. So I had these replaced and it's still exactly the same.

However I've noticed that if I disconnect the battery then the car does not go down at all, which suggests that it's an electrical issue.

So if it's an electrical issue where would be the obvious places to start looking in order to try and resolve this issue?

Thanks,
Mark

Is this the vehicle that had a welding incident prior to the issues?
 

Oldspanners

Senior Member
Joined
Oct 30, 2017
Messages
1,498
Reaction score
1,623
Location
Normandy
Your Mercedes
C CLASS 2004 C180
I replaced airbags on a friends E320 which had a leak around the electrical connector to the valve on the air bag. This may be your problem in that disconnecting the battery stops the leak there.
Buy some gas leak detector much stickier than soapy water and spray it around the electrical connector and of course the air line on the air bag.
 
OP
M

Mar64

Member
Joined
Jun 11, 2020
Messages
10
Reaction score
0
Your Mercedes
2004 Mercedes E320 CDI
  • Thread Starter
  • Thread starter
  • #8
UPDATE; So after 5 days with the battery disconnected the suspension still dropped at the rear!!! I drove it yesterday and when I parked it up - with battery connected - the rear dropped over the space of an hour. Again it dropped both sides at the rear, at the same time.

alexanderfoti; I have had the valve body replaced, so this shouild not be leaking. I will check it again though. Also if this was a leaking air bag issue then it would drop one side and then the other, as I would have thought it unlikely they would have the same sized leak. I have another Mercedes with a clear air bag issue and it drops only on one-side

sidmon; No welding has been done to this car from what I can see.

sheryllee; Thanks, the link was informative. I will check the rear level sensors.

Oldspanners; I've already checked around the bags previously and couldn't see any leaks. Although that is no guarantee that there isn't a leak. However when I've got the rear up I will have a look around the connectors.

Also just out of interest. The Rear Air bags that are advertised on Ebay, the ones around £100 from China. Are these any good? Has anybody any experience of trying these?
 

sidmon

Senior Member
Joined
May 14, 2007
Messages
170
Reaction score
6
Location
Midlands
Your Mercedes
Mercedes 190E 1989 2.0
If it's the car I'm talking about the issue was caused after an exhaust bracket was welded with the battery still on the car causing these issues. If you purchased the car within the last few months it sounds likely to be the same vehicle. That would rule out the airbag's being at fault and would point to an electric issue possibly an airmatic module/ECU issue?
 

alexanderfoti

MBO Forum Supporter
Authorised Forum Supporter
Joined
Mar 25, 2010
Messages
15,165
Reaction score
6,352
Location
Tonbridge
Your Mercedes
W221 S65 AMG - W204 C63 AMG + Various other MB's
UPDATE; So after 5 days with the battery disconnected the suspension still dropped at the rear!!! I drove it yesterday and when I parked it up - with battery connected - the rear dropped over the space of an hour. Again it dropped both sides at the rear, at the same time.

alexanderfoti; I have had the valve body replaced, so this shouild not be leaking. I will check it again though. Also if this was a leaking air bag issue then it would drop one side and then the other, as I would have thought it unlikely they would have the same sized leak. I have another Mercedes with a clear air bag issue and it drops only on one-side

The way the bags are plumbed, they can leak across the rear axle in one go, or both bags can have a leak!
 

V6Matty

Senior Member
Joined
Aug 1, 2012
Messages
9,366
Reaction score
4,223
Location
Newark, Nottinghamshire
Your Mercedes
S212/2010/E350 (His) W246/2016/B200 (Hers)
I seem to remember they were occasionally known to chafe near the T join around the rear axle, as Alex though get yourself around everything with some leak detector to find where it’s hiding
 

malcolm E53 AMG

Senior Member
Joined
Aug 21, 2005
Messages
7,082
Reaction score
4,737
If they are the original airbags like everything they wear out I’ve seen plenty of 212s with ‘sagging posteriors’ with this problem in fact one parked up yesterday. The rear bags generally fail gradually and intermittently a lot of owners being perplexed as to why the car doesn’t drop when the car is stood only to drop the next time the car is used which is probably due to the variation in ground level when the car is parked up
 
OP
M

Mar64

Member
Joined
Jun 11, 2020
Messages
10
Reaction score
0
Your Mercedes
2004 Mercedes E320 CDI
  • Thread Starter
  • Thread starter
  • #13
Thanks for the replays guys.

So I've inspected and sprayed soapy water underneath the vehicle at any airmatic connections and also around the rear Airbags and connections. All appears to be air tight.

I've also taken a look at the rear level sensor and connecting rod. It appear to be undamaged. However I assume that these can't be moved by hand. The reason I ask is that I wasn't sure if it was seized, as the rod and arm was stiff, which I assume is how it's meant to be?

I also briefly took a look at the compressor, however this is brand new as it was replaced not long ago, so I assume it's ok. I did notice that the air filter had not been attached to the compressor pipe when it had been fitted, but I connected this and the car still dropped to the rear overnight. Out of interest does anyone know where on the compressor is the valvebody. It's doesn't appear very obvious?

Also just out of interest. The rear Airbags that are advertised on Ebay, the ones around £100 from China. Are these any good? Has anybody any experience of trying these?
 

pgh13

Senior Member
Joined
Apr 1, 2019
Messages
596
Reaction score
489
Location
Nr Leamington Spa
Your Mercedes
E320CDI 2004 - straight 6 diesel
Arnott also have a good rep. They have how to do it videos on YouTube too. I'd be wary of Chinese ones.
 
OP
M

Mar64

Member
Joined
Jun 11, 2020
Messages
10
Reaction score
0
Your Mercedes
2004 Mercedes E320 CDI
  • Thread Starter
  • Thread starter
  • #16
UPDATE; It was indeed both rear airbags that were at fault. I used Arnott and replaced both. I inspected them afterwards and couldn't see any problem, however all I can assume is that over a long period of time they perish and fail to hold air.

Anyway thanks for all your help.
 

Blobcat

Moderator
Joined
Feb 8, 2006
Messages
39,134
Reaction score
28,041
Location
Grange Moor
Your Mercedes
R171 SLK280, Smart R451, Land Rover 110 County SW, 997 C2S, R1250 GSA TE 40th, CBR600FP
Good hit rate on the forum at the moment :D
 

00slk

Senior Member
Joined
Dec 1, 2012
Messages
9,768
Reaction score
9,540
Location
Cambridgeshire UK
Your Mercedes
2002 SL55 AMG, 2005 E320 CDi, 2014 SLK250 CDi, 2003 SLK200
UPDATE; It was indeed both rear airbags that were at fault. I used Arnott and replaced both. I inspected them afterwards and couldn't see any problem, however all I can assume is that over a long period of time they perish and fail to hold air.

Anyway thanks for all your help.

Have a close inspection of the old airbag and pull the airbag up, you will find where the rubbing has taken place. I too had the same issue and when I replaced the rear airbags couldn't see any damage to the old bags. You'll find a small part that has a very slight rubbing. That's where it is leaking under high pressure ;) The car only has to be parked on very slight uneven ground and the damaged rubber seals itself against the top part of the airbag which stops the bag leaking which also makes it an intermittent fault.
 
Top Bottom