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Teaspoonful?? Auto correct you are the bane of my existence! Should be tapping.
Someone above mentioned Tap Magic as a lubrication solution, and it is a very good one but make sure if you are teaspoonful aluminum to use the Tap Magic made for aluminum. When I worked at a plant that had primarily aluminum parts that's what we used, like I said, never broke one in aluminum. As others have said speed, torque, improper use of the tool in general, all contribute broken taps. I figured if you have a lathe and can machine a part you probably know exactly why the tap broke. Most of the time when I've broken one is because I was into much of a hurry, lacked the proper drill bit, or was using a Chinese tap.
I've broken many taps (never in aluminumn) and have always ended up punching them out our breaking them into smaller pieces. I like your solution, a bit time consuming, but for what you were working with, probably the best solution at hand.
With most car radiators now adays being aluminum and plastic, I doubt see that being a solution. Also every production car I've ever worked on uses the engine to drive the water pump not a separate electric motor. You can however buy one for racing applications which would most likely cost more than what the author of this article spent on the entire project.