At 01:02 PM 9/24/2002, Marla Stelk wrote:
>so what does the thermostat affect?

The water pump circulates coolant in three main loops, one of them from the
right head to the heaters and back to the pump, another around and through
the rest of the engine, and a third from engine to radiator and back to the
pump.

When the engine is cold, the thermostat prevents coolant from returning to
the engine from the radiator.  As the engine warms, the thermostat opens
partially, allowing flow of cooler coolant from the radiator into the
engine to maintain the proper temperature.  If the engine puts out more
heat, the thermostat opens more and allows more coolant to flow through the
radiator, thus shedding more heat and controlling the temperature
rise.  Once the thermostat is open all the way it can no longer control the
engine temp and the engine and radiator temp rise until they trigger the
first speed of the radiator fan which increases airflow through the
radiator and sheds more heat.  If this still can't keep up with the heat
load from the engine, the temp will continue to rise and trigger the high
speed of the radiator fan.  If *this* can't keep up then the engine will
overheat.  At this point you can shed additional heat by turning both
heaters on full blast, but you won't like being in the same vehicle with
it. <g>

david

--
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"