Date: Wed, 24 Oct 2007 21:29:30 -0700
Reply-To: Michael Elliott <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Michael Elliott <camping.elliott@GMAIL.COM>
Subject: Re: Manifold measuring - is this right?
In-Reply-To: <71d9cdf90710241850s24080b5dm6304e0b415cfe3@mail.gmail.com>
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Thanks, Jake.
I wonder if these vac findings make any sense at all:
1. I have been told that if the engine runs differently with/without the
fuel pressure regulator vac line hooked up -- like idles too high with it
disconnected -- it is a vacuum leak symptom. My engine runs a little
rougher with the hose disconnected, but barely changes speed, if at all.
This seems like I don't have a leak.
2. Vac at the fuel reg port reads 10'', and if I give it some throttle,
the vac decreases. As you say, this is normal behavior, but the vacuum is
pretty low at idle, suggesting that I have a leak.
3. Vac from the vacuum unit hose labeled "2" on the left hand photo on
page 24.25 in Bentleys* (hose disconnected from vacuum unit) is about 11''
when the engine is idling, but it will climb up to 18'' or more if I give
the engine some gas. I don't even know whether this means anything at all,
but it's different behavior than when I measure at the fuel reg port.
4. If I pinch the aux air regulator hose per Bentley's when the engine is
cold (AAR is open at first as it should be, I've benched it) the engine
does not slow as it is supposed to. This suggests a vac leak, else what
does the AAR do for a living?
5. I've tried to find a leak by spreading hydrocarbons, like carb cleaner
and propane hither and yon around any and all joints and hoses associated
with the intake manifold and the engine doesn't change speed at all, ever.
Suggesting I don't have a leak.
6. And an odd side finding: Fuel pressure reads around 35psi with that #2
vac line connected, but drops to about 32 with it disconnected (and rpms
increase) though Bentley's says the pressure should be about 29 with the
hose connected and it should INCREASE to 36 or so with it disconnected.
This behavior is opposite of what it is supposed to be.
Folks who know how these things are supposed to work are so impressed with
this latter finding that one said that the hoses must be hooked up
improperly (they aren't), and another would like to see it for himself.
I'm charging admission.
* What is the name of that hose?
--
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 6:50 PM Jake de Villiers wrote:
> 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
> <mailto: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://www.crescentbeachguitar.com>
> http://subyjake.googlepages.com/
