I am trying to figure out how the TPI air injection cooling system works.....There is a heater hose line that comes out of the heater core and into the front/side of the TPI air injection and there is another that comes out from the front/bottom of the TPI air injection and goes back into the block (beside the thermostat housing). Now how do these work....which way is water moving? Is it coming out of the heater core, into the TPI and back into the block? Or is the line from the block pushing water into the TPI back thru the heater core?

If I were to "cap off" the line (coming out of the block) that is in the front/bottom (near thermo housing), would it cause any problems? The neck coming out of the front/bottom of the TPI is slightly cracked and leaking a bit......that is why I ask. thanx.