I have a 1995 940 Turbo, recently acquired.

When I first got it, all the boost was there. Stomp on it and WHEE! you get the nice kick in the seat as the turbo spins up.

One day I really hammered on it... and then the boost went away. Here are my symptoms:

1. When I hit the gas, I hear the turbo spin up (if the windows are down) but then it pressures up and I hear kind of a scrapy/rattly noise. This noise gets much louder when I let off the gas. So kind of a gas->hold->off makes whizz(normal)->rattle->RATTLE.

2. Much decreased boost. I'm still getting SOME, the car drives and rides fine, but nowhere near as much.

Now, problems... I am lucky enough to have the NORMAL tach, which means I have no boost gauge. Until I get to the junkyard, I'm flying blind as to how much boost I have.

A friend guessed that it might be the CBV (Blow-off/Compressor Bypass Valve) but apparently NOBODY sells that separately, or at least nobody I've been able to find.

I pulled off the intake hose and fiddled with the turbo shaft - there doesn't seem to be any play in it. It's not hitting the sides, which is why my friend guessed the valve.

Thoughts? Suggestions? Opinions? Thanks!