power steering issue

[T223]

I have a 1971 F100 4x4. Just rebuilt the steering gearbox , installed a second rebuilt power steering pump thinking I got a bad one. With engine off I spun the wheel back and forth 35 times. Then started engine and let it idle. when I shut it off the power steering pisses out the peehole in the cap. This is with the wheels off the ground. I figure there is air in the system, so Ive performed every configuration of steering the wheel left and right with engine running and with engine off, Ive added fluid when it showed low "with the wheels straight when adding fluid. PLEASE HELP. I even drove it as someone said it might clear itself. No luck, I keep a rag over the pwr steering pump cap to keep the fluid from spraying the engine compartment.