> Just to help me understand - why is it better to put the probe in
> the return
> from the rad to the water pump?
Just my opinion and the difference isn't large ... I wouldn't bother moving
it.
But locating it in the return line allows closer control of the fan ... it
won't run in the situation where the engine is working hard but there is
adequate airflow through the radiator to keep it cool (eg high speed runs).
The fan should only run when the airflow is inadequate, else you are wasting
power (and fuel) turning the alternator that powers the fan.
To put it another way, the fan control forms a control loop, and the fan
affects the radiator outlet temperature directly. It only indirectly
affects the inlet temperature. Direct sensing almost always makes a control
loop work better.
OEMs frequently don't worry about this, because they set the fan to not
engage until well above the thermostat temperature. But most LBC owners
aren't going to like watching the gauge climb over 200F before the fan comes
on ...
Randall
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