brickers:

1985 745t m46 garrett

so I've been trying to track down some problems with my brick, and have recently been focusing on the Compressor Bypass Valve. Just read an article on it at turbobricks and was wondering three things.

1) The article I read mentioned that a malfunctioning CBV would fail to compensate when the trubo is suddenly disengaged and might cause pressure to back up onto the tubro and the unit to suddenly "seize" for a moment. This sounds particular similar to the a mysterious problem I have had over the years but been unable to track down.

Basically when cruising at highway speeds the car will suddenly stutter, and feel liks there was an air pocket in the fuel delivery that caused the engine to cough or something. I had always suspected this was a fuel problem but know my fuel system is rock solid (I've replaced most components over the past 8 months). Is it possible the CBV is actually malfunctioning and that this is causing pressure to briefly overwhelm the turbo? I have noticed it is more common when the cruise conrtl is engaged and the turbo is engaged/disengaged/and then quickly reengaged. Figure if so this could prove useful to a bunch of other people who commented they have been experiencing the same issue.

2) Where on earth can you buy a replacement for this part except volvo?!? I've searched all the online sources I frequent (importec, thepartsbin, volvoworld, fcpgroton, and ipd) and can't find any mention of this part at all. This is particularly odd since the importec catalog is basically just a listing of every possible part, and if it is unavailable it will be listed as such. Being an '85 I have a garrett oil cooled unit with external CBV, and would like to just replace the CBV since the second turbo is only at 50k.

3) Is the CBV just the bell shaped unit on the top that the vacuum line from the intake manifold connects to or is the unit under it (that looks slightly like the oil separator) also part of the unit? What is the grey and red plastic unit that is positioned in the middle of this vacuum hose (sits on top of the crankcase)? Seems like a one way release valve... but its function?

Any repsonses welcome, thanks in advance.

-rt