>i have been noticing that after a short drive i have
>coolant backing up into the reserve tank of my 1.9l.
>so i figure i let some air in the system

Just how much coolant?  I've seen the level in my '85's coolant reservoir
vary quite a bit as the liquid in the system expands and contracts.  There
should always be some liquid in there to keep air from being sucked into the
system as it cools/contracts.

Randy, Carla & Anna Huyck, Olympia, WA
'75 Rustfalia
'85 Vanagon GL
'90 Fox GL
'74 Super Beetle