This is sort of a philosophical question about the design of
the Vanagon 2.1 cooling system.

Here's the key question:
If the radiator circuit flow is restricted, does the thermostat
open the same amount as it would if the radiator circuit flow was normal?

This would lead to a hot running engine.

Some random thoughts:
If the radiator is partly clogged, but cools enough for light
load/cool temperature running, will the temperature gauge
read normal until the cooling system's cooling capacity
is reached?  I'm thinking about this in terms of where the
coolant temp sender is and how the thermostat controls
the coolant flow through the thermostat's manifold:

After leaving the engine, the hot coolant goes into the
bottom of the manifold.

If the engine is cold, the coolant recirculates through the
top of the manifold and to the water pump again.  If
the engine is warm, the coolant from the left head
goes past the temp sensor, then is blocked from going
upward.  So it goes through the crossover pipe to the
manifold on the right side of the engine bay, then up front
to the radiator.

The temp sensor is always measuring the temperature
of the hot coolant in the bottom of the thermostat manifold.
The thermostat is mixing the hot and cold coolant.  Is the
cooling system "tuned" on the basis of normal flows?

tabe johnson/87 westy