Reading recent problems with Vanagons running hot, I would like to relate my experience from a few years ago, and remind us all that with the Vanagons, problems we experience may be caused by some apparently unrelated conditions.
My 1990 Westfalia with the 2.1 L engine was consistently running hot.  It wasn't quite bad enough to do something right away, but it was a concern.  On a trip to Arizona and California, I experienced a flat and had to use the spare.  The next day, driving in hilly country, I checked the temperature gauge and it pegged at below the little red light, and this was in hot weather.  I was shocked to the point, I stopped by the side of the road and checked for leaks and all the usual.
It turns out the spare tire had pinched one of the coolant hoses to the radiator for years and really constricted the flow.  The lesson here is to check everything.

On another note, the old girl reached a milestone a few days ago.  The odometer turned over to 400000 kms.  Click here for some photos: http://picasaweb.google.com/ewieber/20100726#

Cheers
Ed Wiebe