Dave;  Several years back I ran VW Bug with a 100 hp pinto engine in it.
The radiator was in the front with coolant pipes traveling under the floor
pan.  The only way I could get the system to function was to blead the air
of on the highest point, which happened to be the coolant heated choke.  If
you have a point in the hose from the water pump higher than the air bleed,
the system just will not function.  The VW setup pucked out several fills of
coolant before I figured out it wouldn't work with any air in the highest
point.  Good luck.  JohnD