mvoltin1

My 2008 GL450 AirSpring seems to be leaking but need help troubleshooting. The nose sometimes goes down when car is stopped for a while (few hours) but immediately pops up when restarting the car. Also, it is sometimes just the right side and, sometimes, the entire front goes down. I tried to find the leak with soap water to no avail.

My question is whether it is possible that only right airspring is leaking? It would be strange for both sides to go bad at the same time. I would rather not exchange the left side unless I absolutely have to.

On the other hand, if I understand correctly, there is a one-way valve on each airspring (where air enters and another valve for deflating it; leak from one airbag should not cause drop in pressure elsewhere); thus, leaking air in one should not cause the other side to deflate. If this is true, then my both airsprings must be bad.

Can someone help confirm this? thanks in advance.

P.S. Here is what I am considering for a replacement: Arnott airspring

mvoltin1

after reading some more, I have summarized three possible scenarios and before replacing airbags, wanted to make sure I was not missing anything. Here is my question:

1) Both airbags could have failed but this could be unlikely (possible but why both at the same time?). I could not find the leaks but, if this is the case, then I just replace both airbags and problem is gone.

2) It could be only one (the right airbag) that I have to change. I think (please confirm - this could be wrong) there is a one-way valve at each airbag and leaking air from one side should not have caused a pressure drop in the rest of the system? And not sure how it would cause the pressure drop on the front-side only.

3) MercedesMedic suggests that there could be a leak in solenoid (allowing air to leak back to air reservoir) or a leak in air-lines.

So, there could be few possibilities and wanted to make sure I was not missing something. Having both sides on the front end drop confuses me (again, except if both airbags failed at the same time and to the same extent).

Thank you.

Onnzo

Hi there,
Sorry I can't offer any experience but I am having a similar problem on my R class except mine is a little different in that both sides always come down together (if they come down at all).

With yours, I would suspect a line leak or one bag as both are connected meaning one would cause the other to go down. Have you fixed it yet? I would be interested in what your cause was.

thender21

Each strut is a separate air-circuit controlled by the valve block. There are no check valves or other valves in the strut. The valve block has solenoid controlled valves for each strut and one for supply pressure from the pump.

The line from the pump can be switched to atmosphere to vent a single strut or all of them.

The air compressor and valve block should be behind the rear bumper on the right side. Hit the valve block with soapy water and look for leaks.

It's not at all unusual for more than one strut to be failing at the same time. The entire system tends to fail at around 200,000 miles.

Take a minimalist approach to repairing it if you want. Start with the RF strut and recheck. Replace LF as needed. If mileage is high, do the air compressor too.

The best way is to do all four struts and the compressor at once, but the second best way is to do front or back one half at a time.

thender21

Also, when the suspension leaks the compressor has to run a lot more to compensate and so often the compressor needs to be done with the struts.

This system doesn't have a logical reason for two front struts to collapse together as they don't share anything, but keep in mind when one corner of the vehicle sags it will lower other areas as well as they take on the load. So you might see the R/R lower or the L/F lower than normal when the R/F collapses even though they have not leaked.