Joh Wakefield wrote in regards to Mike West's query on air dump:

  Mike went on to ask "By the way, what's an air dump?  Is it like a
bucket
of prop-wash?"  Sorry Mike and others who may not have recognized my use
of
language common to the heating & air conditioning trade.  I simply meant
the
end of an air flow path from which used air is exhaused.  On the
Vanagons, I
believe you'll find one high on each side near the tail end, designed to
take
advantage of the low pressure area induced there by speedy forward
vehicle
movement."

   Your comment regarding cooling air flow (making its end point more
effiecient) led me to wonder about thse silly extra pipes put in at the
FRONT of the heater boxes and extending rearward to apparently bypass air
to the  REAR of heater box when its flaps are closed to car interior. They
are on my 78 bus, not on a 77.   I tossed them away since they block easy
access to valves, and covered the the outlets, figuring this left more air
pressure to cooling the engine, then realized that they helped cool the top
of the heater box so oil dripping on them didn't end up as smoke- and then
left them uncovered.  Do you or anyone have any comment on why these pipes
were added?  Seems like a waste of cooling air when heater boxes are off.
MB in NJ