2007 e550 Airmatic Hissing and constant height adjustments
After getting my tires changed I drove home and parked my 2007 Mercedes e550 4matic with 103k miles for 16 days. When I went out to go drive it, the rear-right wheel was completely tucked in the wheel well. All other wheels looked fine.
I started the car and checked to see if it would correct itself. It raised a little, but there was an inch difference lower than the rest of the wheels. Furthermore, I heard a consistent hissing noise that goes from high to lower pitch in the right wheel well area.
I drove it around to see what happens, eventually, it brought height back to the rear right while on a level surface. As I kept driving, especially on uneven surfaces, the compressor kicks on several times within a minute to keep adjusting the height, like it’s trying to correct it. When I backed up in my parking spot, the rear-right is now the lowest again by far.
Today I put it up on some wheel ramps to try to find the noise, it’s hard to determine with the engine running. I sprayed a bunch of areas to see if any bubbles appeared and I couldn’t find any. I did see the level sensor arm was crooked, I straightened it out and made sure the connector was pushed in. Same issue is present.
Using my scan tool, I manually enabled the compressor and while it ran, I didn’t hear the hissing. I also manually raised, lowered and operated the valves on both rear wheels. They both raised/lowered very fast, and once again… no hissing.
I looked around to see if any wires or hoses appeared abnormal since I had my tires changed, but nothing sticks out. The only other variable is I had the rear differential rebuilt about a month ago, but I don’t recall hearing that noise afterwards.
The hissing only happens when the car is turned on. It’s consistent while the car is running. As soon as the car is turned off, the noise immediately stops.
I’ve scanned for codes various times, nothing suspension related comes up.
Any input would be appreciated!