> >   FIRST the pressure drops precipitously, and THEN the coolant level
> > starts to go down ... FINALLY the temps start to rise (provided the
> > temp sender is submerged in what water remains).
> 
> Just a brief comment on this part.  Coolant level sensors are of
> almost no use in this application.  It is commonly assumed that the
> temp gauge reads low as soon as the sensor is no longer submerged. 
> Not true.  It only drops after the coolant is all boiled away because
> steam will heat the sensor.  If you haven't caught the problem long
> before this, it's too late anyway.
> 
> Tracy


Tracy, please expand on this: "Coolant level sensors are of almost no
use in this application."

Finn

Well, I did say 'almost'.  See later message on this subject.  But for instance, the low coolant level warning on my RX-7 is mainly useful only before the engine is started.  It will stop complaining after the engine starts and runs a bit (especially at high throttle when the coolant is well whipped up by the pump).  When it comes on again, a LOT of coolant is missing.

 So, I think as an in-flight warning, it would not be very useful since when it comes on it will be too late.  But my main point is that there are far better ways to detect a cooling system problem early on.

Tracy