In a message dated 4/12/04 1:45:43 PM, drillock@EARTHLINK.NET writes:

<< I agree, Sam. I have done it both ways, no difference noted. . . .   . . .
Any Vanagon cooling system that depends on blocking that tiny 6mm bypass
needs repair IMO.

Mark >>

I've noted a difference.  It's about 1/2 a needle's width on the temp gauge.
Some time ago, I mentioned that my van ran hotter in the winter than the
summer.  The difference I noted whenever the van settled into the steady state of
being fully warmed was VERY slight.  I assigned this to the coolant being
shunted away from the radiator through the rear heater core when its valve was
opened for winter service.  Shunting the rear heater circuit is not very
different than opening the valve.  So, I think that whether the rear heater core lines
are shunted or plugged doesn't even matter to a hill of beans at the foot of
Mt. Rainer.  Depending on the integrity of your cooling system as Mark noted,
use whatever method which is accommodated by what is in your junk drawer.

George