Hi Paul,

Can you post another pic of this thermostat housing area, with the temp
sensor visible?  Are you saying the stock temp sensor is above the
thermostat?  The water pump housings that I have, locate the temp sensor
below the thermostat, which would be immersed in coolant if the level is up
to the bottom of the thermostat as you described.  Is there any chance this
higher fitting you describe was originally a level sensor?

As for air pockets, my rev-1 system had a pretty big loop of AN-16 hose out
of the top of the thermostat housing, that went all the way down to the
radiator below the engine.  That loop stayed full of air all the time.   I
figured that there wasn't enough flow to force the air pocket down the long
slope and into the radiator.  It seems the hose was large enough to allow
the water to flow along the bottom of the hose, and leave the air in the
top.  It didn't hurt anything, but it always bugged me.

In rev-2, I did away with the air separator tank, and have only an overflow
bottle.  The rad cap is mounted on the thermostat housing (no room for a
thermostat though), so I can actually fill the engine without taking hoses
off (another improvement from rev-1).  I have the option of adding an
aluminum, pressurized expansion tank in place of the plastic overflow tank
if it proves necessary, but for now, I decided that simple is good.

Cheers,
Rusty (running again by the end of this week...really...don't laugh, it
could happen)