Greetings All. Thanks if you’ve seen and / or made helpful comments on my previous posts, but the stiff ride problem continues despite eliminating a few things. Here’s a reminder / update:
The car & history: 2004 S320L cdi, 128k gentle miles, well maintained, mine for past 3 years. Runs on OE 17” alloys with new Continental OE 225/55/17 97Y rated tyres (not XL) at correct pressures, no mods. Recent new front suspension arms, track control arms, wheel bearings, tracking perfect & drives straight. New Compressor & relay at 70k miles. New OE Valve Block just fitted (tested voltage from compressor / solenoids working), new engine mounts. Strut ADS module connectors checked for seating, appear ok.
Persisting Symptoms (despite the above): very stiff / almost non-existent damping at ALL 4 struts (as if defaulting to setting ‘4’ Safety Mode / hard compression & rebound?) even at very low speeds over ruts and ridges (Thump / Bounce, Ouch!). New Valve Block has made ZERO difference to the stiff, skateboard-like ride. ‘Sport’ 1 & 2 setting switches illuminate, but little difference (unsurprisingly?). I did notice a brief burning smell from the front of the car early in my ownership (hidden shorted wiring as someone suggested?), but nothing obvious when inspected.
(Before you ask): Never any ‘sagging’ even when car not used for a few days. No hint of air leaks, struts actuate ok, ride height even & correct, raises and lowers on dash switch. 3 x previous SDS (‘STAR’) diagnostics NO faults shown or stored even when tested on the move. No ‘Airmatic Warning’ signs on instrument cluster. (Before you ask): no, the harsh ride is not q. ‘maybe in my imagination?’ (as one Indie politely suggested - Mmmmm.. no comment). And yes: I’ve driven a ‘healthy’ (suspension-wise) W220 S Class. The difference is night and day - even allowing for the UK’s often poor road surfaces.
I see that a few W220 S Class owners with a similar problem have replaced air struts at huge expense but with no improvement: so I don’t want to go down this route on the off-chance. And, since the problem is affecting all 4 struts (+ no leaks), it seems unlikely that they have all gone bad.
My Question(s): 1. What might cause the apparent default to setting ‘4’ on my Airmatic / ADS but NOT show any fault codes on STAR? (Mechanical, electrical, or a combination?) 2. Has anyone had a similar experience / symptoms and managed to resolve their stiff damping the problem?
Any suggestions to diagnose the problem / restore the Magic Carpet ride which the S Class is famous for? I’m posting this on a few Mercedes forums so will try to keep track of and respond to all replies. Many thanks for your interest in the meantime.
Mark B (UK).
![2647187]()
The car & history: 2004 S320L cdi, 128k gentle miles, well maintained, mine for past 3 years. Runs on OE 17” alloys with new Continental OE 225/55/17 97Y rated tyres (not XL) at correct pressures, no mods. Recent new front suspension arms, track control arms, wheel bearings, tracking perfect & drives straight. New Compressor & relay at 70k miles. New OE Valve Block just fitted (tested voltage from compressor / solenoids working), new engine mounts. Strut ADS module connectors checked for seating, appear ok.
Persisting Symptoms (despite the above): very stiff / almost non-existent damping at ALL 4 struts (as if defaulting to setting ‘4’ Safety Mode / hard compression & rebound?) even at very low speeds over ruts and ridges (Thump / Bounce, Ouch!). New Valve Block has made ZERO difference to the stiff, skateboard-like ride. ‘Sport’ 1 & 2 setting switches illuminate, but little difference (unsurprisingly?). I did notice a brief burning smell from the front of the car early in my ownership (hidden shorted wiring as someone suggested?), but nothing obvious when inspected.
(Before you ask): Never any ‘sagging’ even when car not used for a few days. No hint of air leaks, struts actuate ok, ride height even & correct, raises and lowers on dash switch. 3 x previous SDS (‘STAR’) diagnostics NO faults shown or stored even when tested on the move. No ‘Airmatic Warning’ signs on instrument cluster. (Before you ask): no, the harsh ride is not q. ‘maybe in my imagination?’ (as one Indie politely suggested - Mmmmm.. no comment). And yes: I’ve driven a ‘healthy’ (suspension-wise) W220 S Class. The difference is night and day - even allowing for the UK’s often poor road surfaces.
I see that a few W220 S Class owners with a similar problem have replaced air struts at huge expense but with no improvement: so I don’t want to go down this route on the off-chance. And, since the problem is affecting all 4 struts (+ no leaks), it seems unlikely that they have all gone bad.
My Question(s): 1. What might cause the apparent default to setting ‘4’ on my Airmatic / ADS but NOT show any fault codes on STAR? (Mechanical, electrical, or a combination?) 2. Has anyone had a similar experience / symptoms and managed to resolve their stiff damping the problem?
Any suggestions to diagnose the problem / restore the Magic Carpet ride which the S Class is famous for? I’m posting this on a few Mercedes forums so will try to keep track of and respond to all replies. Many thanks for your interest in the meantime.
Mark B (UK).
