David:

THANKS for a clear, concise explaination of the
coolant system. Coolant systems and thermostats can be
pretty confusing...but your email clarifies it nicely.
Good Show!

kevindobrien@yahoo.com

--- David Beierl <dbeierl@ATTGLOBAL.NET> wrote:
> 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"

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