Sometimes you may have to bleed air out of the waterpump. Once in a great while a buble will get trapped in the pump and it will not prime. If that is the case then you are not moving any coolant and it may overheat. Doubt this is the problem though.
1978 CJ7, frame off rebuild, NV3550, Dana 300(twin stick with a sight tube), I6(258), Dana 44 Scout Axles with 4.09 gears, truetrac LSD. The rest yet to be decided.