>>Mine did that, among other things. I found a hole in the little one-
>>way valve in the vacuum line that runs fron the intake naifold, all
>>the way forward to the power brake servo. Replaced the valve
>
>    Thanks for the reply. However I am not aware of such a vacuum
>line on my bus. Would I have found it when I removed the engine? Is is
>possible that my '71 does not have one? and should it? Also, what is
>the purpose of this vacuum line? Sorry for all the questions, but I
>am now worried I may be missing something important.

Well, I thought all the '71 Buses had power front disc brakes. Every one
I've seen has them, any way. But I admit I am not an authority on the
subject-- anyone ever seen a '71 bus WITHOUT power front discs?
Maybe drums, or nonpower discs?

Mine has this vacuum line coming from a fitting on the intake manifold,
where the vertical tube from the carb joins the horizontal tube that
goes to the cyl heads. The line goes up and to the left, and curves
around the fan shroud to go forward thru the front (FIF) engine sheet
metal. Some where right after that, this rubber hose joins a betal tube
that runs forward under the bus floor, to near the master cylinder and
power brake booster (a drum-shaped device about 12" in diameter, maybe
6" thick). The master cylinder is bolted to this booster., and the metal
vacuum line has a rubber hose on it that goes to the booster too.