Hi, fellow rotary enthusiasts.  I decided to temporarily take the thermostat
out of my 13b for initial run-ups, testing and ECU programming.  When I
removed the thermostat, there was coolant right up to the bottom edge of the
thermostat. However, you could look up and see the water temp sensor, and it
was in an air pocket.
     I've been following the many posts that are currently being sent
discussing cooling issues.  I have installed the "closed" system, with a
pressurized expansion tank with the radiator cap on the aluminum expansion
tank, and no additional overflow bottle.  From what I am reading, it sounds
like a few short runs should eliminate this small pocket of air, and only
take a small amount of coolant from my expansion tank.  I am assuming that
since the coolant is all the way up to the bottom of where the thermostat
normally would be, that the water pump is fully immersed, and should start
pumping coolant as soon as I start the engine. I would assume that this
would be turbulent enough to splash coolant up into this small air pocket so
that the coolant sensor will be touching coolant? I am rather surprised that
Mazda put the sensor in this location, in that it is so high that if there
is any air in the system, that's where it's likely to be. Maybe Mazda wants
us to know the air temp inside the engine? (Only kidding) If all this sounds
correct, my question would be mainly:  how long or short of a duration
should these runs be to try to purge the air out of the system? Are we
talking about something like 60 seconds or more like 5 minutes ?  I
installed a "real" throttle cable and throttle assembly today. No more coat
hanger run-ups.  Thanks so much for everyones assistance here.  Paul Conner,
13b powered SQ2000 canard