Tri-Pac not starting after coolant hose blowout...

[Waterloo]

I'm trying to think how I would pull a vacuum on the Tri-Pac? Pull it up front under the hood at the truck's coolant reservoir bottle? The TK manual had the instructions on purging the air, it was as I described using the petcock valve under the thermostat housing. Of course it sounded like a one shot deal prior to the initial start of the motor, but it took four or five tries to get this air out. Now I'm curious as to how to do this, as I know I will be doing this again in the future with my Tri-Pac. It seems to be the weak link in my truck's systems. She is a bit long in the tooth being 10 years old.