Adam;
    The next thing I would suspect is the water pump. The impellars wear
down leaving the pump unable to efficiently move coolant at low speeds.
    Do not fret about replacing those other parts, they will pay off in the
long run.
Ken Lewis
86 Transporter Crew Cab
60 356 T-5 Porsche
http://neksiwel.20m.com/
Vanagon tech, pixs, O2 monitor gadget
>But there still is a wierd problem.  It seems that the pressure cap allows
coolant to leave the system into the overflow, but it does not suck it back
in. .......