SFML320

I've been hearing what sounds like a air release noise from the passenger side whenever I come to a stop. Usually it's more noticeable right after we start the car.

Anyone else hear this?

I'm thinking it can wait until I bring the GL in for the free tire rotation to have a tech take a look.

jpeardm

I only hear the whoosh release noise after I shut the engine and the last door is closed. I don't think I've heard it while the car is running or when starting. Maybe someone else has heard it other times??

SFML320

Yeah I hear that too, which i think is neat to watch the vehicle squat back down. But I can't figure out what the other noise is when I'm coming to a stop.

jpeardm

There have been a couple of reports of failures in the air suspension involving compressors or other components. I think it been very rare and in early builds but I would get it checked out.

nantucketsleigh

Not so rare. My GL 450's air suspension failed at 2000 miles (Nov 2006 build). Dealer says its quite common and keeps a stock of new compressors at hand. About a week ago I saw an new ML550 at the dealer with a failed compressor.

StevethePilot

I'm with jpeardm, I only hear it after I shut the car off and get out. I just thought it was releasing all the air pressure it needed to keep my great mass off the pavement while I'm in the driver's seat!

SLR199

We get a lot of 164's with failed compressors. Im guessing when you bring it in, they will more than likely tell you the compressor is faulty. How many miles are on it?

oknish

Faulty air compressors, especially in the early GL build cycle, were very common. I have 3 owners who have had the GL for a year or more and all 3 have had airmatic failure.

SFML320

Ouch! a little over 1K miles on it right now. the air noise is coming from the front passenger. it makes sense, as the noise is apparent only during braking. i guess the weight on the compressor is causing it to release the air?

SFML320

actually, i notice the car will lower/level itself if you are idling or stopped for a long duration. i believe the air suspension raises the car for a more "comfort" ride but lowers itself for easier exit and entry.

StevethePilot

I sometimes got that with my LX470. I think that what it is doing is, it's added pressure to keep the nose from dipping too much at the stop light, and it takes a moment or two for it to re-correct and remove that extra little bit of pressure from the front of the system. I believe that's what makes it look like the car is dropping a bit at a stop light.

STP

03LX470

I get a squeaking noise from the front end when going over speed bumps (at 10 km/h). Any sign of suspension problem?

StevethePilot

Wow, there are a lot of possibilities when you're going that slowly. It could be a bushing or a tie rod rubbing on something or the valve for the suspension letting air through in such a way that it sounds like a squeak. I assume you've discussed it with a service advisor? If so, what'd they suggest?

STP

Zerocarpileup

im also getting this "whoosh" noise. I get it while braking mostly but have heard it while driving and after parking the car. sounds like the airmatic is releasing air along with a rubbery squeal. anyone ever have this

mike278

I know the noise you're talking about, my 2011 GL450 does that. I've been meaning to check into it because it is not normal on the earlier models. I'm inclined to think it is a design upgrade for the later models, maybe to get rid of moisture in the system kind of like an air line dryer for a shop air compressor. My vehicle is not having any suspension problems (at the moment) so I don't think it's something abnormal. Maybe someone who knows the real story will chime in.

BlownV8

My 2007 GL450 has always made the woosh noise. It's usually when I unlock the door first thing in the morning or sometimes while driving as well as when I exit the vehicle after a long trip.

islandbeef

From my understanding, it's how the GL levels itself. I have a longer driveway with an incline, the car does it's best to level itself while the car is stopped on the driveway (and we unload the Costco groceries, sporting goods, etc.). After unloading and driving the car into the garage and shut off (where the ground is level) I'll hear the "hissing" noise, assuming the air bags are still trying to level the car, even after the car shuts down.

alx

the air release should not be happening when the vehicle is in gear. that is how i have seen it.

Jhorn20

Had the same issue.
Bottom suspension link on which the air shock absorber sits on.
Cost £240 plus 2h labour

Jhorn20

This is correct.
To much "Woosh sound "while driving normally relates to suspension relay(fuse) or air compressor.
Apparently common fault is relay which keeps compressor in ON setting at all times. It can cause damaging compressor.

TacSysResearch

Had the same issue and could hear the sound, like a pressure relief valve opening, when approaching stop signs. I complained several times and got no help. An independent mechanic said the Benz isn't supposed to make noises like that, so I kept bugging the dealer. They finally admitted it was an issue, and what they told me is that there is a "silencer" on a relief valve that's supposed to muffle the noise and that the hose had come off of the silencer. The release of air was said to be normal and when they put the hose back on (assuming they did so) the noise once again only became noticeable when outside the car, in the garage, either when shutting down or when opening the door to get in and go.

WaveyKat

mines make the Same noise at stop signs/Traffic Lights etc.. do you have a part number for the so called baffle?

WaveyKat

so today i took out the fender liner to check out the hissing sound.. the noise is coming from the pump intake hose which has a filter on it i replace the filter which is a mann filter 212-320-0169 or mann filter wk32/7.. its a basic fuel filter they used.. i am still getting the hissing sound.. but i then found this see link below ..its some sort of noise damping mat. now its to find it

http://workshop-manuals.com/mercedes...ic_compressor/

JamesMitchell

I've owned my '07 GL450 since new. It currently has 190K miles. I replaced the air compressor and front struts about 1.5 months ago. No codes in the suspension system with MBII and all of the struts are proper height and not losing air. Been noticing a louder and longer hissing sound lately. It's usually when the last door is shut when parked and then this loud and prolonged "TTTttttttsssshhhhhTTT' sound. Ever since it was new, it's always had the normal "Phstt" sound sound when closing a door when parked. But ever since the new compressor was installed, the sound has become much more pronounced and longer. I found this thread from a few years ago and the link in the post above describes a damping mat that was used in the vicinity of the Air Compressor Filter Assembly. Couple of questions: Has anyone ever heard of this damping mat? Does it work? (I could not find it on the internet). Is the air compressor filter hose also the discharge hose that makes the noise when closing the door and/or is there a separate discharge hose/port on the air compressor. If the air compressor filter hose is also the discharge port, will replacing the air compressor filter help to alleviate the loud noise upon closing the door? Btw, I don't think the air compressor filter has ever been changed. I know it's supposed to be a maintenance item. I just haven't ever replaced it. This is the car's third air compressor (this latest one is a free replacement from Arnott and I did install the new relay that came with this latest compressor). This seems to be an occurrence across many different airmatic models, and after searching I still haven't found a definitive answer. Any thoughts are appreciated!

DennisG01

I don't think I can completely answer your question, but I'll offer an opinion on what it "generally" seems like the issue is. It sounds like you're saying you're experiencing an extended pressure relief (phstt). If so, to me, that sounds like something is partly clogged, not letting the air out as fast as it should. That could also, in theory, lead to longer compressor run times and early (er) failure. To your question on whether the filter is the issue (and/or the discharge path)... maybe try disconnecting the filter for a short drive? See if the sound changes?

I would think (again, though, without fully knowing) that the discharge is a separate spot than the filter/intake. Possibly looking/googling for pictures of the valve block would help?

You mentioned that you replaced the compressor... do you recall anything on it that would indicate the discharge happens there?