when i fill my radiator to the neck it drops a little below the neck is this normal on 95 z28 camaros. also when bleeding the system do both screws need to come off. the one on the thermastat housiong and the heater hose.

 

Open up both bleed screw. Run engine till hot with both screws open and eadiator uncapped. When coolant starts to circulate in radiator, add coolant to top, may have to do several times. Put cap on radiator and allow air to blow out of bleeders till coolant comes out. Close bleed screw, add coolant into overflow tank to prevent air from getting sucked in when engine cools.

 

I personally just use a machine to do it. Take it to a shop and muster out the $60. I work there so I get everything at cost pretty much, but they have a vacuum and sucks everything out of the block, radiator, and heater core. Then the vacuum from the motor sucks the new fluid in there.