Take your brake booster hose off, block the hole on the intake manifold, start the engine, does it run good?, Hook up a vacuum pump up to the brake booster line, draw a vacuum on the brake booster system, if it holds a vacuum, most likley it is good, if it won't hold disconnect at the booster and check the booster itself, if it won't hold a vacuum replace the booster, if it holds the vacuum, find the leake in the line going to the booster.

--- On Tue, 8/5/08, Max Wellhouse <dimwittedmoose@CFU.NET> wrote:

> From: Max Wellhouse <dimwittedmoose@CFU.NET>
> Subject: Just Gotta Be A Vacuum Leak!!
> To: vanagon@GERRY.VANAGON.COM
> Date: Tuesday, August 5, 2008, 9:36 PM
> Troops:  In my saga of poor performing () GL 2.1 motor
> syndrome, I
> went through the Haynes British manual I got from Bus Depot
> and went
> through their troubleshooting guide.  With all my
> performance issues,
> the one thing that keeps showing up in their analysis is
> Vacuum
> Leak.  Sure, low compression and fuel injection issue come
> in 2nd and
> 3rd, but I don't have hot and cold start issues which
> both state that
> low compression could be the cause of that.
>
> I do also have a lot of travel in my brake pedal despite
> repeated
> adjustments to the rear shoes and the front disc pads have
> plenty of
> meat left on them.  Under their listing of "excessive
> brake pedal
> travel", they list sevo vacuum leak, and shot brake
> servo.  I don't
> know if this makes the scales tip one way or the other, but
> if I were
> to pump the brake pedal repeatedly9 or 10 times(when the
> engine does
> try to idle every once in a while), the engine idle
> increases
> substantially.  Is this further evidence of something
> wrong?  Crack
> in one of the plastic pipe joints going back from the servo
> to the
> engine?  Gasket at a joint bad?  The one way valve failing?
> The o
> ring at the master cylinder?  How would I check the servo
> visually to
> see if it's toast?  I do have the servo here from the
> 91 shell I just
> parted out, but how would I tell if it was any better than
> the one I have?
>
> If I were to try and isolate this problem, could I simply
> plug the
> booster outlet and drive the van for a short while without
> the  servo
> sucking vacuum?  Probably have a harder time stopping the
> van.  This
> engine pretty much doesn't want to idle period.
> I've gone back and
> checked the valve clearances again and I'm happy with
> that part.  I
> am tapping vacuum from the FPR port to run both my vacuum
> gauge on
> the dash and the MAP sensor for the Haltech ECU as well as
> the FPR,
> but I've been doing that for years with no problems.
> Again, the
> ether spray showed no engine rise or fall in rpm when
> spraying all
> the likely leak spots, so I'm pretty much in another
> fork in the road.
>
> Thanks
>
> DM&FS