I don't know the first thing about wasser-boxer's but the temp warning
light in my dad's Polo (a little VW, smaller than a Golf, in case you 
don't get them in your neck of the woods) blinks for a short time after 
starting up. It's always done this since it was new. Is this the same in 
Vanagons? I don't know why it does it or what its supposed to tell the
driver but its bloody annoying. Serves him right for not buying another
bus and then borrowing mine :-)

Andy E.