I'd say you want a -4 line from the front (rear in car) sidehousing (Mazda
knew what was right so use the port that is already there) to the higher port
(not the overflow) on the filler/expansion tank. Us a -6 or so line from
bottom port on exp. tank to the pump outlet or highest point in cooling
system. If the tank is the only filler point it is kind of a pain to fill
the system but after that it's no problem. Keep tank 1/2 full when
cold.
I assume Tracy, you refer to this port.
this fitting is the same type as the heater port on the other
side. should I remove it [and if so, how? are they pressed in or
threaded?] and install an AN type fitting, or simply run a -4 rubber line with a
hose clamp? kevin