Im reading all the way through this thinking the exact same thing. when I did my first waterpump replacment on an LT1, I didnt put the driveshaft on the new pump. didnt even know it was there cause when I took off the old waterpump, it stuck to the waterpump. I never took it off and installed it on the new pump cause I didnt know it was there. when I cleaned off the eng. and got it ready for the new pump, I just thought it was part of the pump, and didnt bother to compare the new one to the old one on the back side. if thats in place, Id say you need to bleed it. but, contrary to what someone else suggested, NEVER bleed the coolant with the eng. running on any car. that will not get the air out. the system was designed to be bled w/the eng. off. like all GM engines. good luck and let us know what you find tomorrow
chris

 

You did remember to put the thermostat in the new pump didnt you chris?Maybe thats what took me so long I didnt use the proper bleed procedure.I probably would not of had as much of a problem if I just bled it with the engine off.

 

Confirmed... Service Manual states that the bleeder valves are to be open during the refilling of coolant. Once the bubbles disappear and coolant flows, then tighten the bleeder valves.

Start engine remove radiator cap once again with engine running on a cold engine... as it warms the coolant level will drop and replenish with distilled water and coolant. Once the level tapers off replace the radiator cap.

It doesn't take much time to do this and don't let the engine get to operating temps during this procedure. Wear eye protection always to prevent ethelyne glycol from burning the tissue on your eye (chemical burn).

 

Take off the inspection plate to make sure its turning. My friend left off the drive gear coupler on mine and it would start to heat up. What a pain in the butt.

 

the 2 female gears is there, i turned the one on the waterpump with my hand to see if the pump spins on the inside before i installed it and all hoses are hooked back up correctly

 

i know it sounds amateur..but is it possible you stuck the thermostat in upsidedown? Ive heard it is possible and it fits both ways..if thats the case..I guess this could cause it to get really hot really fast
Just another thought..I know when I just installed my new WP...i did that exact thing..i told myself for two days..'remember to put that dowl back on the WP backside'..guess what..when i installed it..cranked it over..the fluid didnt move..car got hot..and i was like WTF!!!
Well I noticed this little cylindrical thing sittin on the floor oops..! Put that back on and the car is great now. I just know it is possible your thermostat could be upside down..if thats the case..probobly the most simple one to fix good luck let us know what it is! Derek