Date:         Mon, 09 Oct 1995 09:23:00 -0700 (PDT)
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Maher, Steve (SD-MS)" <SMAHER@PO2.GI.COM>
Subject:      RE: VW-71 BUS-CHECKING FOR INTAKE MANIFOLD VACCUM LEAKS



>However, when I was driving in some hills today, the Bus lagging and
>smelling warm, I noticed that when I braked for a stoplight, the foot
>pedal was stiff like you feel with the engine off.  Went away and never
>felt it again (the lagging continued, however).  QUESTIONS:

Are you sure you're not driving my bus by mistake? <g> Your description
fits mine to a T.


>1)Could it be a leak somewhere between the engine and the booster?

Bingo. Mine did.

>2) Is there an easy way to check the lines?

Not really. But if you lie on your back underneath the bus, and spray
every vacuum-line joint with your carb-cleaner, you might hear a change
in RPM where there shouldn't be one. Or, you can just replace all three
lengths of vacuum hose. I used about 6 feet of 1/2" I.D. wire-reinforced
heater hose, available from Napa for about $2.80/foot. This stuff is much
stiffer than ordinary heater hose-- you could drive a tank over it without
collapsing it. It needs STRONG clamps, and a hefty ooooommpph on the
screwdriver.


>3) What if I were to disconnect the line out of the manifold, plug it and
>the manifold outlet, and drive it to compare the change.  WOULD THE BUS
>BRAKE OK???  I understand that more foot pressure would be needed.

Yup. takes getting used to, and a heavy foot, but the brakes are actually
quite smooth, once you lean on them enough. I drove mine for about a week
this way. I weigh 220, which helps.


>4) If there is a leak in the line, and I plug the outlet and let the Bus
>idle, would the idle speed be faster/slower/same than if I had the
>allegedly leaky line connected?

Depends on how your idle is set up now, to make up for the leak if there
is one. You'll probably have to readjust various idle settings. But you'll
find that it steadies down a LOT once you do. At least, my 30PICT-3 did.


>5) What is that little round connector on the vacuum line?

A one-way valve, that lets the engine suck air out of the booster, but
doesn't let air back into the booster. If your brakes get real stiff as
soon as the engine conks out coming to a stop, then this valve is bad,
or else you have a BIG leak between it and the booster. VW doesn't have
this valve any more (unless you find on old one still on the shelf), but
some aftermarket foreign-car places still do. Call around. My replacement
doesn't look at all like the original, but fit and works beautifully, for
about $9.00.



>6) Any other suggestions about where my problem lies?

34PICT carbs suck generally, and are notorious for poor idles caused by
even slight misadjustments. Get a Weber progressive! but be prepared to
grease a few palms during emissions-test time.  ;)


 -Steve Maher   smaher@gi.com   '71 VW Transporter w/all the above problems