Pimps, Players, & Bricksters,

I can not figure this one out. My 1990 240dl has just started making this hisssssing sound when I accelerate. Could the check valve be on the way out? Since it is an old piece, I plan to replace it for posterity. Where do I get a replacement -dealer or auto store- as I have never purchased such an item? I can't imagine AutoZone, or the like, having something like that on a shelf.

Obviously, this is a vaccum related issue. I thoroughly checked out the archives and discovered that C. Herbst had the same drama in his ride... the link... http://www.brickboard.com/RWD/?id=320247

No firm solution is indicated anywhere by anyone. Have a clue? Please help! I did the blower motor last summer and feel comfortable digging into that area, however, I would like to have some idea as to the problem. Cracked line? Busted tee? Could the accumulator, or some other "vaccum pot", suddenly develop a leak? The switches and vents are working. It is a hiss that starts on accel and quits soon after. Very wierd to say the least.

I will go out to my ride and quickly check some hoses... any help would be greatly appreciated!!! Thanks, Jon