2001 S500 Airmatic issue
 

This w220 has an issue with the rear shock bleeding down. They sag quickly, within min. Overnight they are bottomed out. I suspect the rear struts to be the issue but not sure how to confirm this. I can’t hear the air leaking out. I wanted to confirm that the valve block is not the issue. I disconnected the line from the pump and submerged it. I am getting a bubbling but not sure if this is a large enough leak to condemn the valve block. According to the DAS laptop the valve block passed the leak test to both the reservoir and the pump.

https://youtu.be/7nKAdXGVaUk

There isn't a good test for the block. If the shocks aren't recent replace them first. Then replace the block if they keep going down.