Zeni84

HI everyone,

First off I want to start by saying thank you to everyone in advance for taking the time reading this, also I want apologize in advance if this thread is been discussed in the past. i am new to MB and new to this forum so please bear with me

I recently purchased a GLS 450 and I love the car. I am impressed with the performance and the smooth ride the Airmatic offers.

The fun didn’t last long as I got a Airmatic malfunction light on the dash and the next day all for wheels to the ground.

I could hear the compressor running but the car would not raise.
I went to an independent mechanic (local dealer was booked for weeks). After checking air-springs and struts he ran a compressor test with Xentry which you could clearly see the compressor not putting more than 1.4 BAR out of 14 BAR required.Kinda disappointed for the compressor to go out at 57k but glad i have extended warranty.
I asked him to go ahead replace the valve block and the filter as well as I didn't want to run into more issues.

After replacing Air Compressor, Valve Block, Filter (all genuine parts) everything seems to work fine and I get no codes on the dash or with my Autel tool.

Now here is what is bothering me:

Every time I start or turn off the car I hear a loud woosh air blow off noise what I think it is pressure relieve, which I know it is normal for this cars but it was not this loud before.
What got me paranoid is that it does that sometimes while driving.
Also want to mention that the car doesn’t seem to drop overnight.

Went back to the shop and they said it is normal and after “arguing” for some time it was clear they don’t know why is that loud, so it was not worth pushing it.

Has anyone experienced this after replacing the components mentioned above?

Any info would be much appreciated
Thank you in advance!

John CC

Ours does not make any noises that I have noticed, nor does it appear to drop over night. (Not much help, I know, but...)

Since it makes the noise while driving, I wonder if it is somehow over pressurizing the system, or running when it shouldn't? (This may explain why yours failed.) Truck air brake systems blow off excess pressure regularly. Is it like that?

Zeni84

Thank you for your response John CC

Its almost sounds exactly like a truck blowing off excess air.
You read my mind, I believe some how is over pressuring the system which is why I am thinking on replacing the relay (if I can figure out which one is for the Airmatic can’t find much info on that) as I read different threads on older models the relay fails.

Zeni84

Air blow off noise solved!

As i stated above Air compressor Valve Block and Filter was replaced form and independent mechanic that kept insisting that it was normal air release noise.
After couple of weeks of back and forth I knew I needed to get my hands dirty, it took me 15 min to find the hose from Filter to Compressor not clamped from recent repair therefore it was completely detached (picture attached shows the very small detail missed by mechanic)
I attached the hose to fitting, clamped it and done NO MORE annoying ,stressful noise.

I hope this helps someone else with same symptoms, if you hear a loud blow off noise and everything else seems normal i would check the filter hose or filter itself.