Sagging Rear Suspension
I've got some familiarity with air suspension systems on my old Touareg and current Cayenne but I am now in the market for GLS and could use some input from the folks here. A '18 model at an MB dealership came up for sale kinda close to me and the sales guy sent over a couple pictures. One of them shows the car on the lot with the rear end sagging significantly. I raised the issue with him and even asked him how it was CPO'ed if the suspension sags. His response was that "they all do that when parked for an extended period of time". Now, in my experience this has never happened on any of the air suspension equipped cars that I've owned. It's a sealed system and if the car is sagging that means there's a leak. The sales guy is adamant that everything is ok and that it was properly checked over by the service department.
Usually, I would just chalk this up to the usual "sales guy not knowing the mechanics of the car he's selling" syndrome but he later sent over a picture of a brand new '22 GLS sitting on their show room floor that is also sagging in the rear.
What do you all think? Is there any validity to this? Is there any documentation to support his claims? I'm still hesitant to believe him.




My '13 GL450 also settles or deflates if it has been sitting over night. I agree that it is a sealed system but I wouldn't rule out that leaks could be coming from may places within the system. Fittings (tee's, elbow's, 4 way's and couplings) or a hairline crack in one of the lines going to and from the bag or the compressor. From what I understand, and read on here and a couple of other forums, the compressor is adding air to the system multiple times while the vehicle is in use as needed.
When I jack the car up to change the fluids or when I got new tires and wheels put on, I set it back on the ground the bags have completely deflated, looks like I put a drop kit on it! Start the car and within a few seconds the car is back to its original height. Right or wrong, I am not too concerned with it, if one of the struts fail then I will simply change it and move on, no big deal.
Chad
What am I gauging here? Should I measure the drop overnight to see how much it dropped in a given time? Should I time the on/off cycles of the compressor to see what's it running and for how long?
What parameters should I be using and or monitoring to see if what my car is doing is an indication of a failing component?
Thanks man!
Chad
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What am I gauging here? Should I measure the drop overnight to see how much it dropped in a given time? Should I time the on/off cycles of the compressor to see what's it running and for how long?
What parameters should I be using and or monitoring to see if what my car is doing is an indication of a failing component?
Thanks man!
Chad
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bakestein1;
What you have experienced is normal, mine does the same thing every time the wheels come off the ground. Oil change, differential fluid change, trans fluid change, brake fluid change, rear end fluid change or any other reason the car is off the ground it thinks its flying!
When you come in for landing the car goes Chicano and on the floor it sits!! Which for about 3 minutes is kinda cool looking, then the car rises and goes back to normal configuration.
My first oil change I thought I broke something because it was on the DOWN low. Wife was crying, dog was howling, kids were running. Went inside to get on this forum to see what in the hell I did to the car, came back outside and it was sitting normal. I thought I was losing my mind, I could have swore that car was broke and now it looked normal. Even contemplated not drinking cold beer while working on it!!
You should be good to go!
Chad
Last edited by Tiffany's GL450; Jun 17, 2022 at 08:14 PM.
The trick is to just open one of the doors, even if you just pop it open and then mostly close the door. The suspension is basically not allowed to move while any of the doors are open, thinking that there is someone entering or exiting the vehicle and so it wants to stay as still as possible.







