96 Monte Carlo 3.4L

[Earl1450]

New to this, so bear with me. Was replcing front brakes when I saw coolant drip. Had to replace waterpump. Also replaced belt and hoses--why not, already had it apart. Owner's book said to bleed coolant system when refilling. Did that. First drive and temp guage was real erratic. Went to operating temp., then would start rising and almost peg, then back down to normal. Was talking to a buddy, said I had an air bubble in the system. He let me borrow his vacuum tool (don't know the tech name for it) to refill the cooling system. Did that 5 or 6 times--opening bleeders again until no air coming out. Still having the same trouble. I recently bought a manual sensor/guage to put in, but I also was told there is a seperate sensor for the guage. I haven't been able to find it--anyone know where to look? Also, the fans don't seem to kick on consistently. I've seen other posts regarding the fans--don't know if they are working right or not. None of this started until I changed the waterpump.
Any ideas?

[pocket-rocket]

I would agree with your friend about the air bubble- temp sensors can't accurately read steam. The sensor for the in dash gauge is in the lower intake, just behind the t-stat under the throttle body. When I change t-stats, I usually drill a small hole in the outside edge and put that hole at the top when I put the stat in to help bleed air out of the system.