Did you find the source of the coolant leak? I was suggesting putting the expansion plug into the radiator neck below the overflow tube and adapting the air to the center bolt that expands the plug, but your way seems to have worked also.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!