> My 3M tells me
> the hottest pipe from the water pump to the thermostat housing is only
> 196F

Is that the large-diameter metal pipe to the left of the engine? If so,
that's the "cold" water coming back from the radiator. If the thermostat is
open, the upper chamber of the T-stat housing is sealed off from the lower.
The upper half takes water in from the radiator and feeds it to the water
pump via the metal pipe on the left. The temp sensors (in the lower section
of the T-stat housing) are reading the water temp as it comes out of the
left head, before it heads to the right via the crossover to the water
manifold to join the water from the right head on its way to the radiator.

--
John Bange
'90 Vanagon - "Geldsauger"