While we're on the topic of overheating at idle I'd like to bring up
something I've been thinking about lately.  When a vanagon idles, temp goes
up, fan cycles on to cool it, but at idle the water pump does not seem to
move the volume of coolant from the motor to the rad at a fast enough rate
for effecient cooling.  Perhaps I have to much time on my hands but I've
thought about a clutched two speed pulley for the water pump that  would in
effect double the flow rate at idle. Is such a thing thechnicaly feasible?
Thinking aloud Jim.