Well, you can read it for different situations, but idle is where you need
to be if you're looking for leaks.

The throttle plate is closed, so the vacuum is pulling harder at any gaps.

On 10/24/07, Mike Rocket J Squirrel Elliott <camping.elliott@gmail.com>
wrote:
>
> Should the engine be idling, or what, when measuring vacuum? Could be
> doing this wrong.
> --
>
> Mike "Rocket J Squirrel" Elliott
> 71 Type 2: the Wonderbus
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> KG6RCR
>
> On 10/24/2007 4:34 PM Mark Drillock wrote:
>
> > I would use the vacuum line to the fuel pressure regulator.
> >
> > Mark
> >
> > Mike "Rocket J Squirrel" Elliott wrote:
> >
> >> Hi, I'm looking for leaks in the intake manifold. Bentley's doesn't
> give
> >> a procedure for checking intake manifold vacuum so I'm winging it. I
> let
> >> the engine warm up so that aux air regulator thing is closed, and then
> I
> >>  pulled one of the hoses going to the vacuum unit on the dizzie and
> >> connected it to my fine Harbor Freight vacuum gauge.
> >>
> >> This is a 1.9L engine and the hose I'm using is the hose labeled "2" on
> >> the left hand photo on page 24.25 in Bentleys.I don't know how
> >> appropriate this hose is, but it has fewer bits connected to it than
> the
> >> other one. There's also a hose going to the fuel pressure regulator,
> >> maybe it's a better choice?
> >>
> >> ANYWAYS, when the hose is disconnected from the vacuum unit, the idle
> >> hunts up and down. The vacuum gauge shows around 18psi -- depending on
> >> engine rpms. I can open the throttle and the vacuum might drop to
> 10psi,
> >> then climb back up . . . I really have no idea how one goes about
> >> measuring vacuum.
> >>
> >> --
> >>
> >> Mike "Rocket J Squirrel" Elliott
> >> 71 Type 2: the Wonderbus
> >> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> >> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> >> KG6RCR
> >>
> >
>

--
Jake
1984 Vanagon GL
1986 Westy Weekender "Dixie"
www.crescentbeachguitar.com
http://subyjake.googlepages.com/