Temp gauge or Coolant temp sensor?

[LeDevil]

Tonight after work I put in a new Fail safe 180 degree thermostat and Coolant temp sensor. Both of mine were pretty nasty. I ran the truck until it got warm (middle of the gauge) then I let it cool down and topped off the radiator I did this about 5 times until the level of coolant didn't go down any more. Well my temp gauge started working after the new Sensor was put in but now if the truck idles it will stay below the half way mark nice and cool but as soon as I drive it it will peg past the "H" like way past the "H" it just barrys the needle!
I'm hoping that the Sensor is just bad but if any of you have any ideas or opinions what would cause please let me know as this is my daily driver.

Thanks LeDevil

[Brad]

Those are pockets of air in the cooling system that are doing that to the gauge. Nothing to worry about and it'll take a week or so of daily driving to get them all out and back to consistent temps. Meanwhile you'll still need to top off the radiator a few more times.

[LeDevil]

So as long as I keep the coolant full I shouldn't have anything to worry about right? Thanks for the reply I figured the air pockets were already gone because the coolant stopped going down.

I'll see you tomorrow and I'll bring that small air cleaner for you if you wanted to swap still.