Thisis my first post here, but have been using these forums since I purchased my 2007 E350 4matic Wagon in July of 2016. It was used but seemingly in great condition. The previous owner took care of it pretty well especially on the inside, I got it at a little over 98k miles. Due to my work I've put on 12k since then...

Right now at this moment these are the things I know I need.. I need new alignment, tires, new rear breaks, and I have a torn boot on my right front axle. All things I will be replacing myself soon except the alignment. Gonna just replace the whole axle as opposed to rebooting it.

Lately I have been having a lot of vibrations at higher speed of 60mph or more especially in the rear. I know it's not the boot because that makes a specific rattling noise. I just the other day put on some good used tires on the back until I get my alignment and replace the front axle first. I was thiking these issues were what was causing the vibrations until I came out the other day and my back passenger side was sunk with the well touching the tire. Of course it rose when I started the car but it is doing it everyday now, and the entire passenger side (front and back) sits a little lower than the drivers side.. I checked the bags and sprayed them with soapy water and found no bubbles and no clear damage either. I checked the compressor and it is functioning fine. The filter was dangling off of it's connection to the frame so I reattached it, of course not my issue.. I have been reading that the pulsation damper can malfunction causing a rough ride and high vibrations. Can it make the car sag overnight though? Im thinking not. Whatever the case I cannot find it anywhere to even check it.. I looked on the rear axle and only saw what i believe was the level valve, but hard to access. Keep in mind I only have rear sls no airmatic and no manual controls.

It's driving me nuts trying to diagnose it. With all the stuff I already need to do I can't afford to just swap out the bags at their cost so I need to try and find if it could be a less expensive solution first. I don't know if it is related, doubtful but I am also smelling gas from the same rear wheel well.. I had tge fuel tank replaced from the recall so I know it's not the sending units. Could it be a leaking shock? I wouldn't think the smell of a leaking shock would smell like fuel or anything at all but I'm at my wits end. Thank you in advance for any help and I hope I was detailed and clear enough in my explanation.

 

Driving nuts is right.
That is how engineers design the car
Anyway, to troubleshoot the system you need to monitor the elements.
Can you read the system pressure?
You said the compressor tested good. How did you do it?
Having no scanner who could read the system at the time, I added pressure gauge on my wagon, what made whole troubleshooting a breeze.
About $30 in parts and 20 minutes of labor.
BTW I had vibration on my wagon, that was resonating with wheel turn at freeway speeds.
Drove me nuts for well over a month till I replaced control arm bushings.

 

I did not test the pressure in the compressor. By working fine I mean I watched it come on, pump the car up and then cut off.. I'm starting to really feel like it's the airbag even though I see no leak and it holds all day until overnight.

 

Again, guessing is not going far on the system where you have several interlocked components.
Just becouse compressor comes up, doesn't mean it pumps the required pressure.
How long did compressor run?
If you see single bag dropping down and soapy water test finds no bubble, the other possibility is that the valve leaks back and combined with bad check valve -dumps the air via the system.
Unless you can get some gauges on it, the guessing might go forever.
Swapping parts is always the option

 

Well it stays on for a few seconds while it's rising and then cuts off. I have a buddy that has some tools I don't so I will look into getting a pressure gauge to test it. It may have always been this way and never noticed it but the right side sits a half inch lower than the left. I think I read that this is normal though. Just never paid attention until the first time it fell. The valve I'm sure is a lot cheaper than the bag so I'd hope that would be it. I believe the valve is located on the rear axle near the bag in question, is this correct? Is there a way to test this without a pressure gauge? I have pretty decent general knowledge of cars but have never had to deal with air suspension on any previous car. I love this wagon as it is a rarity, but being a rarity it has few write ups and videos on it.. I've been googling and you-tubing for the past week.

 

I assume non-airmatic that is to say only rear has air springs front is conventional, common for affected side air spring internal valve to malfunction suggest replacement. OEM replacement part # is 2113200925. MB recommends air springs be replaced in pairs if mileage is 50,000 > rebuilt http://www.rebuildmastertech.com/ aftermarket https://www.arnottindustries.com

 

That is correct only bags in the rear. So the internal valve of passenger bag only is common culprit? I had hoped this was not the case as these are not cheap. Thanks for the info, I was pretty sure that the bag was defective..

 

Meant to say common for rear air spring internal valve to fail, either side.

 

Thought so, appreciate your input.