Paul,

If you're really concerned about the air pocket above the
thermostat, you could make a couple of mods around your expansion tank.
(I went back and had a look at some pictures you posted recently.)

The upper fitting on the tank currently goes to the back side of
the pump housing, under the thermostat.  I would add a bleed valve to
the top of the elbow on the thermostat cover (highest point in the
system).  OR, Something as simple as a 1/8th NTP solid plug on that
elbow which could be removed when you're filling the system.  If you
want to get fancy, install another small line from the top of the elbow
to the top of the expansion tank.  Also, I think the tank should be a
little higher on the firewall so that it is well above the block and
thermostat.

Just my 2 cents

Neil

PS: Nice installation.

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of sqpilot@earthlink
Sent: March 8, 2004 10:08 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] air pocket in cooling system

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



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