Rear air suspension
09-30-2021, 04:18 PM
#1
Junior Member
Thread Starter
Rear air suspension
Hi. My rear suspension is trolling me. After parking the car the suspension can sag completely within 1hour. After I can start the car and let it fill up and then leave the car over night without the suspension sagging.
This does not feel like leaky airbags, it feels more like either the valve block is sometimes leaking or the ECU is for some reason deflating the airbags randomly while parked.
any suggestions what can be done to locate the problem and perhaps rule out the airbags as the source of the problem?
This does not feel like leaky airbags, it feels more like either the valve block is sometimes leaking or the ECU is for some reason deflating the airbags randomly while parked.
any suggestions what can be done to locate the problem and perhaps rule out the airbags as the source of the problem?
10-08-2021, 07:34 AM
#2
Junior Member
Thread Starter
Does anybody know what valve/valves that are used to lower the suspension?
is it the valve block or is there also a valve in the compressor?
is it the valve block or is there also a valve in the compressor?
10-08-2021, 03:58 PM
#3
Out Of Control!!
Join Date: Jul 2003
Location: North Scottsdale, AZ
Posts: 15,903
Received 4,435 Likes
on
3,152 Posts
'71 Pinto
The following 2 users liked this post by konigstiger:
MantaTIC (10-08-2021),
SteadyRover (12-05-2021)
10-08-2021, 04:47 PM
#4
Junior Member
Thread Starter
thank you very much. However I have already checked for leaks at the compressor, valve block and air bags but did not find any which makes me believe that either there is an intermittent leak in some valve, or that there is an intermittent fault in ride height sensor or something causing the car sometimes to sag while parked.
Wife said today that the car sagged while she was shopping, sometimes it does not sag at all for days parked over night.
Wife said today that the car sagged while she was shopping, sometimes it does not sag at all for days parked over night.
10-08-2021, 05:37 PM
#5
Out Of Control!!
Join Date: Jul 2003
Location: North Scottsdale, AZ
Posts: 15,903
Received 4,435 Likes
on
3,152 Posts
'71 Pinto
Last edited by konigstiger; 10-08-2021 at 05:52 PM.
The following users liked this post:
MantaTIC (10-08-2021)
10-08-2021, 05:53 PM
#6
Junior Member
Thread Starter
Based on this I posted info to familiarize you with system. Problem could be compressor y36/8, 8y3, and/or 8y4 or airline to rear. I suggest you focus your attention here. Rear air springs do have internal volume & level valves unlikely both springs would fail at the same time barring bellows damage to both.
one thing I have noticed that I think is odd is that even when the car is locked the air suspension system seem to be partly active. If I lift one rear side (or maybe also both?) the system releases air in order to lower again to the correct height.
I would have thought that the system would be off when parked and locked.
A functional description/diagram of the system would have been nice.
10-08-2021, 05:57 PM
#7
Junior Member
Thread Starter
does the air springs on s213 really have internal level valves? I don’t see any cable connector on the air spring and when googeling there seem to be none. On the s212 however there seem to be a internal valve in the spring.
Trending Topics
10-08-2021, 05:58 PM
#8
Out Of Control!!
Join Date: Jul 2003
Location: North Scottsdale, AZ
Posts: 15,903
Received 4,435 Likes
on
3,152 Posts
'71 Pinto
Searching while you posted see attachment.
The following users liked this post:
MantaTIC (10-08-2021)
10-09-2021, 08:28 PM
#9
Junior Member
Thread Starter
02-02-2022, 05:40 PM
#10
Junior Member
Thread Starter
After replacing the valve block without any difference I replaced both rear air springs. In one of the old I could confirm a very small leak that might have been sealed sometimes and sometimes not depending on the level the car was parked (uphill downhill etc).
with new air springs the problem with the suspension sometimes going flat is now gone.
for some reason I believe that even if only one airbag has a leak the system compensates the height of the other side to match also when parked, has this functionality changed between w213/s213 and older models? On older models it seem like if people had problem with air springs only one side was dropped when parked.
with new air springs the problem with the suspension sometimes going flat is now gone.
for some reason I believe that even if only one airbag has a leak the system compensates the height of the other side to match also when parked, has this functionality changed between w213/s213 and older models? On older models it seem like if people had problem with air springs only one side was dropped when parked.
02-03-2022, 03:41 AM
#11
MBWorld Fanatic!
Join Date: Dec 2006
Location: Europe
Posts: 6,382
Received 295 Likes
on
247 Posts
223.168 & 213.012 & 906.633 & 214.005
After replacing the valve block without any difference I replaced both rear air springs. In one of the old I could confirm a very small leak that might have been sealed sometimes and sometimes not depending on the level the car was parked (uphill downhill etc).
with new air springs the problem with the suspension sometimes going flat is now gone.
for some reason I believe that even if only one airbag has a leak the system compensates the height of the other side to match also when parked, has this functionality changed between w213/s213 and older models? On older models it seem like if people had problem with air springs only one side was dropped when parked.
with new air springs the problem with the suspension sometimes going flat is now gone.
for some reason I believe that even if only one airbag has a leak the system compensates the height of the other side to match also when parked, has this functionality changed between w213/s213 and older models? On older models it seem like if people had problem with air springs only one side was dropped when parked.
Also when driving it would be a safety nightmare if the opposing side suspension was dropped just to reach balance with the leaking side. This is talked a lot on MB forums but the suspension really only works when the car is woken up (note that the car may temporarily wake up e.g. to dry up the HVAC core after being parked for an hour or so, not sure if suspension levelling gets activated or not).
02-03-2022, 05:33 AM
#12
Junior Member
Thread Starter
The S213 with rear axle levelling does not adjust suspension when the car is in sleep mode, neither does the W213 or S213 Airmatic. If the air spring at one side leaks, the load on the the spring on the other side increases a lot (weight transferred via the torsion bar). This on one hand makes the other side drop too but it may also result to air leaking either from the air spring or via the valves.
Also when driving it would be a safety nightmare if the opposing side suspension was dropped just to reach balance with the leaking side. This is talked a lot on MB forums but the suspension really only works when the car is woken up (note that the car may temporarily wake up e.g. to dry up the HVAC core after being parked for an hour or so, not sure if suspension levelling gets activated or not).
Also when driving it would be a safety nightmare if the opposing side suspension was dropped just to reach balance with the leaking side. This is talked a lot on MB forums but the suspension really only works when the car is woken up (note that the car may temporarily wake up e.g. to dry up the HVAC core after being parked for an hour or so, not sure if suspension levelling gets activated or not).
Ok then it could be that when the pressure on the other side increase the valve block leaks or opens (mechanically) to prevent the pressure becoming to high and causing components to fail.
This should explain why I initially thought the valve block to be faulty, I disconnected the pressure pipe from the compressor and strapped a ballon on the pipe and left the car over night. In the morning the ballon had inflated and I thought there was a leak in the valve block or that the car compensated for something and opened the valve block on purpose.
thanks!
