> based on the original poster's assumption that the water pump has to work
> relatively hard to pump coolant uphill, would it do less real work if the van
> were constantly driven downhill?

Forget differential equations.  If it's a closed non-leaking system, it doesn't
matter how the van is facing, the waterpump is only overcoming the frictional
losses in the system, not pumping up or down.  I.e. the more piping, the more
friction, the more the pump has to work.

Uphill and downhill don't matter because the starting and stopping point for
the fluid is the same.  If the van is facing downhill, for every unit mass of
coolant that's going downhill, another unit mass is going uphill and vice versa
if it's pointing uphill.

-Karl

Karl & Kristina Bloss, Trexlertown, PA - '87 Weekender "Bev" - 199K Miles
http://www.enter.net/~bloss/vw - vanagon@makarov.com
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