I have 2000 S500
I believe I have a air leak from the right front air strut.
When I go over a speed bump I hear a hissing noise from the right front area of the car and if the engine is off the air suspension loses all air.

Hello - yes, this sounds like a leak. I'm attaching a link to our site's catalog for your S500's suspension. Please let us know if you have any questions or please feel free to give us a call at 888-280-7799 and one of our MB part specialists will be happy to help you out!

PelicanParts.com - 2000 Mercedes-Benz S500 Base Sedan - Suspension & Steering

MB offers a repair kit to reseal the TOP of the front struts IF that's where the leak is. ............Open the hood and spray some soapy water in the area where the pneumatic line attaches to the strut, then bounce the car a few times. If that's where the leak is it'll be easy to see.........