ok I went to NAPA and picked up a tire valve core, the type that has a rubber gromit and a nut to tighten or clamp it in place. I drilled a hole in the cap of the master cylinder and installed the valve core. I put pressure in it from my compressor but it leaks around the threds of the cap so I can not keep a steady pressure. yes the rubber o ring is in the cap. what the hell is next?