bypass valve

[Dan Masi]

> -----Original Message-----
> From: Joshua Van Tol [mailto:josh at spiny.com]
> Sent: Thursday, February 08, 2001 6:21 PM
> To: quattro at audifans.com
> Subject: RE: bypass valve
>
>
> >I just noticed that these valves are in the wrong way. I
> wonder if that's
> >why they are failing. High pressure comes in from the side
> of the valve, not
> >the bottom (see SJM on bypass diagram) If the high pressure comes in
> >directly opposite the vaccuum hose (ie botttom of valve)
> it's easy to see
> >why it fails.
> >
> >Hmmmmm... It would appear dahlback has screwed up!
>
> Nope, they're in the right way. The inlet is in line with the vaccuum
> hose connection, and the outlet is at 90 degrees to the other two. If
> they were in wrong, they'd never open.

This may or may not be relevant, but in the case of the A4 1.8t's Bosch
valve (and the Forge valve that some have been replacing the Bosch with),
that description is most definitely backwards.  The high-pressure, or
inlet,
side is the connection that is 90-degrees to the vacuum and outlet
connections.  Connecting these valves backwards, so that the high-pressure
is connected opposite the vacuum connection, will cause the valve to open
and leak boost early.

Dan Masi