Bankroll

I'm replacing the front Airnatic struts on my E55, as a preventative measure. I'm going with new Bilsteins. The left side I got at a fair deal from an online commercial seller, but the right side was from a private eBay seller, at a price too good to true! It is new, appeared to be in good as new shape, but in a beat up box.Went to install it it, and found that it is not pressurized. Also, it's been collapsed a couple of inches. And it fails the wiggle test, which both Bilstein, and Mercedes calls out as being defective, or scrap. Has anyone here dealt with this issue before? I plan on returning it, and buying a fresh right side strut, this time. Live and learn.

E55Greasemonkey

The struts will lose air pressure after being stored a long time, just like your tires. When I replaced both my fronts with Arnotts, I also got a great deal on one side. When I got it, it was new and never installed, but the production date was some 4 years old, it had been sitting on a shelf. The rubber bellows was soft, no pressure at all. Arnott's instructions tell you to check this before installing. I went ahead and used it, and had no problems, no leaks, afterwards.
I've never heard of the wiggle test, but take MB's WIS with a grain of salt. There is a lot of German engineering fantasy in there.

Bankroll

The wiggle test is my terms. Mercedes, and Bilstein show, putting the strut upside down, and trying to move the shock at the forked end, side to side. If you have movement, the strut is junk. I'm going to activate the leveling valve, and fill the strut with low pressure nitrogen, and re inflate the bellows. I have pulled the boot down so I can see what's going on.