Airmatic
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Joined: Feb 2021
Posts: 204
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From: Lower Westchester, NY
2018 s560v4
Airmatic
Does your car remain at the same height overnight.
I’ve arbitrarily measured and find that the car lowers itself by as much as 1/2 inch over night.
Is this normal or just the beginning of a more serious issue?
I’ve arbitrarily measured and find that the car lowers itself by as much as 1/2 inch over night.
Is this normal or just the beginning of a more serious issue?
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From: Cincinnati
2010 E350 4Matic
The puzzle for me is that doesn't the airmatic drop down when you turn it off for ease of entry / exit and does it drop down further after you get out? I am assuming that the poster is measuring it with it off and out of the car so I don't understand the additional drop.
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From: Land of 10,000 lakes
AMG GTC Roadster, E63s Ed.1, M8 Comp. Coupe
Our airmatic always adjusted when parked. The initial leveling after driving up our steeper driveway and some settling over time. Not big questionable drops like the in the old days (W220) but a little bit. Had it overnight or weekends.
Last edited by Wolfman; Mar 15, 2021 at 04:51 PM.
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All Cars Lost To Hurricane Isaac (W124 E420 revived - added 88 Allante 14 S550, 17 S63
logically this means that the "psuedo-closed" system has to leak in some way - by design, because if it where a truly closed system you would not need a continually available AND functioning air supply
all of my S's have dropped a small amount when parked. I remember checking one of my cars years ago, and the drop happened pretty soon ( an hour +/-) after I turned the car off and it stayed there pretty indefinitely.
The small drop will typically be noticeable to the attentive eye but otherwise appears normal.
My old ABC (hydraulic) S55 w220 would sit on the front tires (or was it the rear?) and IT did require repair..... I do recall that in all the time I had that car, this and the mass air sensor were the only issues the car ever had.. rock solid..
FUN WITH MB: sit in your car with your car running and turn so that your feet are on the ground.... over the course of a few minutes you will feel the car rise and fall... even more noticeable after the new is worn off (havent tried it for all my airmatic cars but it also did this on the hydraulic cars)
Last edited by kafklatsch; Mar 15, 2021 at 09:42 PM.
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From: Venice Florida
2018 S560
As I remember if you turn the car off and park it in the raised height position from the button with the car on it on the left side of the center console the car will stay in the raised position until you hit the button again when the car is in the key on position.
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From: Maryland
2024 S580
Very normal. Mine pumps up some every time I start it up.
Felt this this afternoon after I washed it!
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W222 S550 4Matic and Jeep Wrangler Rubicon
Much like the air pressure in your tires, the air pressure in the Airmatic strut changes by a few PSI based on ambient air temperature. Your pump will activate when you start the car to pressurize the system and bring the vehicle up to normal ride height.
However if you come out to your car and the top of any tire is completely buried in the fender, then there's a leak in the system - mostly likely the strut. And if that starts to become the norm, then you're close to failure. The system will do its best to compensate for a component that's leaking air, but that starts to put stress on the pump and the pump relay.
So if the change in height is minor and immediately adjusts to normal upon startup, then you're okay. But if the change is significant and happens quickly when the car is off or happens often when the car is off, then you need to get the Airmatic system checked.
However if you come out to your car and the top of any tire is completely buried in the fender, then there's a leak in the system - mostly likely the strut. And if that starts to become the norm, then you're close to failure. The system will do its best to compensate for a component that's leaking air, but that starts to put stress on the pump and the pump relay.
So if the change in height is minor and immediately adjusts to normal upon startup, then you're okay. But if the change is significant and happens quickly when the car is off or happens often when the car is off, then you need to get the Airmatic system checked.
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Joined: Dec 2006
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All Cars Lost To Hurricane Isaac (W124 E420 revived - added 88 Allante 14 S550, 17 S63
Much like the air pressure in your tires, the air pressure in the Airmatic strut changes by a few PSI based on ambient air temperature. Your pump will activate when you start the car to pressurize the system and bring the vehicle up to normal ride height.
However if you come out to your car and the top of any tire is completely buried in the fender, then there's a leak in the system - mostly likely the strut. And if that starts to become the norm, then you're close to failure. The system will do its best to compensate for a component that's leaking air, but that starts to put stress on the pump and the pump relay.
So if the change in height is minor and immediately adjusts to normal upon startup, then you're okay. But if the change is significant and happens quickly when the car is off or happens often when the car is off, then you need to get the Airmatic system checked.
However if you come out to your car and the top of any tire is completely buried in the fender, then there's a leak in the system - mostly likely the strut. And if that starts to become the norm, then you're close to failure. The system will do its best to compensate for a component that's leaking air, but that starts to put stress on the pump and the pump relay.
So if the change in height is minor and immediately adjusts to normal upon startup, then you're okay. But if the change is significant and happens quickly when the car is off or happens often when the car is off, then you need to get the Airmatic system checked.
Thread Starter
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Joined: Feb 2021
Posts: 204
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From: Lower Westchester, NY
2018 s560v4
The dealer just replaced my Airmatic strut as I complained that it was loosing some air (not a lot) overnight as well as hearing a slight clunk if the car was raised and just slowly going over a few bumps. Repair was covered under warranty. Sometimes it pays to have a little OCD. lol
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2014 S550 AMG, 2017 XT5
As I remember if you turn the car off and park it in the raised height position from the button with the car on it on the left side of the center console the car will stay in the raised position until you hit the button again when the car is in the key on position.
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Joined: Aug 2015
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2008 GL 320 CDI
As it turns out one of the height adjustment sensors was broken off. It sounds like that and the new struts will hopefully do the trick, but I'm still keeping my fingers crossed. thanks for all the feed back, Will
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From: Southern Mississippi
1984 W126 300SD & 2013 W221 S550
Normal, Normal, Normal. System is based on the W221! They are designed to re-level the vehicle after occupants have left, thus reducing stress on the system. Some people report it even purges the entire residual charge tank, however I am not certain. I will do research on this tonight and I can post the Mercedes documentation of system functionality. One thing that begins to annoy people, with vehicle age, is the purge valve will make a very rapid whoosh. I don't know how to resolve this other than replacing the air compressor, as replacing the inlet hose and filter did not fix my issue. It has grown on me a bit and I laugh some days, because sometimes it sounds like a squeaky fart, while other days, it highly annoys me.
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Joined: Jun 2021
Posts: 26
Likes: 20
From: Southern Mississippi
1984 W126 300SD & 2013 W221 S550
As an inquisitive engineer, I too thought it was the ambient temperature, but I did the following years ago, I ran the car when it was about 60 degrees outside late one night, I then checked the car height several days later when it was 96 F outside and the car was still lower by a bit. It was an experiment for me. Another time I drove the car around with a scan tool connected, and it would show the pump come on periodically to correct ride height with no apparent change to the ambient temperature. That fact this this periodic activation repeats for a car with no "drop" issues gives some insight into the system.. just my humble insight .
So after driving the car extensively, I'd lock out the suspension (MBs can't do this?), add a set amount of air, and then allow the car to fully go cold approximately 10-14hrs. After checking the pressure the next day, I found a unique anomaly, as the pressure drop wasn't decreasing by the rate of ambient temperature drop, but something more significant. What I failed to factor in is that, air temperature within the tire well and physical temperature of the axle assembly is higher than ambient air surrounding the vehicle. So, I took measurements of the air temperature of the wheel well, and axle assembly, and used the higher value. After this the pressure drop with respect to the parts and surrounding area acclimating to ambient temperature of the city, the pressure drop was normal with the calculator I was using.
P.s. I am also a very inquisitive engineer.
