Has the OP determined that no coolant was his problem, I wonder? [Later edit, answering myself: yes, he added on to his first post that he had AC the next day.]
Bliss36 wrote:
... a MUCH easier way...
FWIW, I submit that the easiest way might be to push a button for a few seconds, although it took some plumbing and wiring. I got tired of needing to find a hose, get down to the waterline and flooding the pump via the through-hull. I considered a bleed valve that was more accessible than lifting the engine hatch (a PITA) and settled on a scheme that fills the pump with fresh water via a 24vAC irrigation valve and a check valve between the AC pump inlet and the pressurized fresh water system. If the pump needs priming, pressing a momentary-on switch for a few-seconds does it.

