So, I have replaced 3 of the 4 structs in our 2011 GL450. First was the front passenger because that side had a leak and was dipping, whereas the driver side was still appearing to be fully inflated (along with the rears). Then, the rears started dipping 6 months later. So I replaced both struts and air bags.

This morning, saw the driver side dipped...and I figured it was only a matter of time, however I saw the passenger side was also dipped about equally. To me, this almost seemed like the vehicle chose to let the air out equally as opposed to a leak.

Is there any specific reason for the vehicle to do this. The passenger front strut is probably 18 months old, I can't imagine it is leaking...and I actually am not sure the driver side is either if they both went down about equal distance.

Thoughts?

It tries to level the car.

Actually, this may be a valve block issue.

Try slowly unscrewing ONE of the hose screws under the hood to release air in either front strut (driver's side has easier access than passenger side). If this causes both sides to drop, then you might have a failing valve block (one valve stuck in the open position) which would explain why both sides drop even if only one side has a problem.

You could choose to replace the valve block (although not [absolutely] necessary), but you'd probably still have to replace the failing strut.

I will look into this. So how would I know which strut is failing? Statistically speaking, it is likely the drivers side since that is the only one I haven't replaced..

I guess I don't understand the anatomy of this vehicle to understand why releasing the air in 1 strut would cause both sides to drop.

The car has level sensors and will seek to be level and will detect the one shock being low as the vehicle parked on uneven ground. It will do this to a point but once it goes completely flat the other side will not follow it down that low.

Thanks.

You can see in these 4 pics, the 2 low ones look equal, and once I turned the car on they both rose to what you see in the pics. They appeared to be the same the next day (raised).

Driver Side low (strut that hasn't been replaced yet)

Passenger side low (strut was replaced a year ago)

Passenger side raised

Driver side raised (strut hasn't been replaced yet)

Most likely a bad strut but you may also want to make sure the level sensor is able to move throughout the range.

I ordered a new Arnott strut last night to replace the driver side. I realize I am 'assuming' that is the bad strut...but it is the one that is likely 8+ years old, whereas the passenger one was installed Jan 2020. The other 3 struts I've installed are all Arnott.

I wasn't aware of the level sensor....I will have to look that up and whether it is 'able to move' as I didn't realize that is a thing.