'18 GLS450 with Sagging Rear Suspension
I posed this over in the GL forum as well (mistakenly) but it probably belongs here more than there.
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 a 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.
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I posed this over in the GL forum as well (mistakenly) but it probably belongs here more than there.
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 a 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.
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I just found this post searching the internet. Our car just has the same problem I think. How much was the repair from the dealership if I may ask? Thanks.




I did the compressor myself on ours....EASY fix. You do not need to be too awful mechanically inclined to do it (you have to be able to take off a tire, PS front)....what happens, the bags sag, the pump burns out....
https://www.fcpeuro.com/products/sus...t-166320010480
All in all, about 30 min to swap them out.
Last edited by OldManAndHisCar; Jan 17, 2025 at 07:55 AM.








For us, we got a warning light that said "Air pump over heating" (or something similar). I saw it first when I was raising the car to change the oil (I assume yours has the same lift ours has). We had a slight leak in the pass side air line, a pin hole in the pipe that was super easy to just replace.




My GLS allows you to raise the car for ground clearance (maybe all the Mercedes SUVs have this) which I do when I change the oil. I noticed that every time after changing the oil and lowering the car to the normal ride height it would be sagging the following morning. Start the car and the air pump and leveling system would reset the car to the correct ride height. I had my car in to an independent shop to replace a bad passenger side rear wheel bearing and I had them install the Bilsteins while they had the rear hub assemblies off which they did for an additional $300, but they were right in your face while doing the wheel bearings.
There are some fairly good YouTube videos about how to do it.














