Originally Posted by Mxfrank

"I read in another thread that it could be too high of a crank case pressure shutting off the rack via the vacuum shut off. This could be the problem. Has anyone ever taken apart the oil separator in the air filter housing? It seems I may be having a restriction there. Or the air filter is also pretty bad. No air through the filter the turbo can and will intake air from anywhere it can including from the brank case breather."

It's next to impossible to have high pressure in the crankcase with a turbo car. If you could install a pressure gauge on your valve cover, you'd find that the crankcase is under negative to neutral pressure almost all the time. If this isn't the case, it would be due to bad rings or valve seals. This is because the turbo draws air like a shop vac, even at low rpm's.

The separator in the valve cover works like a PCV valve. It prevents the full vacuum of the turbo from acting on the crankcase: it's supposed to be a restriction. If it wasn't restricting vacuum, the turbo would suck all the air, oil, and loose parts out of the valve area and crank case. Your engine would surge not sag, because it would be fueled with engine oil as well as fuel. You'd also be leaving a fine black smoke screen in your wake. Oth, if the separator valve was stuck closed, crankcase pressure will build until the car stalls. You'd also be spewing oil out of the weakest seals on your motor. But do change your air filter.

To directly answer to your question, I know of nobody who's disassembled the valve cover components and written about it. This is because the assembly is held in place with rivets of some sort, which appear to be non-removable. Another brilliant Mercedes design: if the separator valve fails, replace the entire valve cover. I'm hunting for a cheap valve cover to experiment with, so watch this space.