Airmatic query
Thread Starter
Newbie
Joined: Jun 2015
Posts: 8
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From: Bridgetown, Western Australia
S430L 1999 W220
Airmatic query
My 1999 S430L Airmatic drops at the front sometimes, overnight or after a few days of non-use. I start it up, get the "Too low!" message and then the car pumps up and all is well. As a former 6.9 owner I'm sort of used to this behaviour (without the alarmist message on the dash), but I don't know if I should be worried in this case. I don't seem to have any leaks at the top of the strut.
So, should I worry/panic yet?
So, should I worry/panic yet?
Thread Starter
Newbie
Joined: Jun 2015
Posts: 8
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From: Bridgetown, Western Australia
S430L 1999 W220
Looked at those posts, very helpful but it still seems to come down to the "replace this, if that doesn't work replace that, if that doesn't work, replace the other...". I was hoping for a shortcut based on my experience - both sides of the front drop, but not the back (noticeably anyway). Looked at the infamous relay, not Siemens, not Hella, but Tyco!? Thought they made toy trains. I'll organise a Hella replacement anyway.
Looking through the service records that I have it seems the car had a new pump and relay back in 2007. Possibly a replacement RH front strut in Dec14, and a heap of invoices hand written by a service place in Dublin, unfortunately by someone who could not actually write. Then there's a host of service records in Spanish from when the car lived in Barcelona.
Anyway, I'll swap out the relay just to eliminate that from my enquiries and see what transpires.
Looking through the service records that I have it seems the car had a new pump and relay back in 2007. Possibly a replacement RH front strut in Dec14, and a heap of invoices hand written by a service place in Dublin, unfortunately by someone who could not actually write. Then there's a host of service records in Spanish from when the car lived in Barcelona.
Anyway, I'll swap out the relay just to eliminate that from my enquiries and see what transpires.
MBWorld Fanatic!
Joined: Dec 2012
Posts: 2,473
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From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
The relay will not cause one end to drop.
You have a pump that supplies compressed air as called for by the controlling computer. The computer reads three sensors - one on each front suspension upper arm, one on the rear sway bar - to determine the need to add or remove air to control the ride height.
The compressed air from the pump goes to a reservoir and to a valve block. The valve block has computer-controlled solenoids to add or remove air from each strut, with an individual air line from the block to each strut.
The compressor runs only when the ignition is on. This means that a small air leak in a strut, air line or valve will not be noticeable when the vehicle is operating, but will cause one or two struts to drop while the car is sitting. If one front strut drops, the other strut will have difficulty hold the weight, so the entire front may appear to be low. Try to see if one strut only is leaking.
Air leaks may be at the top of the front struts, at the rolling diaphragm inside the strut, at an air line, or at the valve block. Soapy water brushed on will check most external locations. Generally speaking, only a failed diaphragm requires strut replacement.
You have a pump that supplies compressed air as called for by the controlling computer. The computer reads three sensors - one on each front suspension upper arm, one on the rear sway bar - to determine the need to add or remove air to control the ride height.
The compressed air from the pump goes to a reservoir and to a valve block. The valve block has computer-controlled solenoids to add or remove air from each strut, with an individual air line from the block to each strut.
The compressor runs only when the ignition is on. This means that a small air leak in a strut, air line or valve will not be noticeable when the vehicle is operating, but will cause one or two struts to drop while the car is sitting. If one front strut drops, the other strut will have difficulty hold the weight, so the entire front may appear to be low. Try to see if one strut only is leaking.
Air leaks may be at the top of the front struts, at the rolling diaphragm inside the strut, at an air line, or at the valve block. Soapy water brushed on will check most external locations. Generally speaking, only a failed diaphragm requires strut replacement.
Last edited by wallyp; Jul 26, 2015 at 09:06 AM.
Thread Starter
Newbie
Joined: Jun 2015
Posts: 8
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From: Bridgetown, Western Australia
S430L 1999 W220
My thoughts also regarding the relay.
I am suspicious of the replacement of a strut in Dec14 - the invoice says "replace rf shock (supplied)" by a BP service station. I'll start the soapy water spraying around that one next weekend...
I am suspicious of the replacement of a strut in Dec14 - the invoice says "replace rf shock (supplied)" by a BP service station. I'll start the soapy water spraying around that one next weekend...
