An air bubble when starting cold is none of the things described above - it is compression going into cooling system. Some times coolant goes into cylinder - sometimes compression goes into coolant - 7 out of 10 times its compression into coolant and well, that will make it overheat evertime.
BEst way to bleed cooling system - I've down over a 1000. Raise front up, heat on front defrost full blast. Fill cooling system with bleeder screw cracked open. Fill until bleed screw leaks coolant. Start engine - top off coolant. Rev up and down and up and down and hold at 3500 for 15 seconds. Rev up and down and don't stop until there is heat from defrost - a lot of heat and be sure to top off and put cap on before thermostat opens or it all comes out. Test drive - let cool - check level and add or subtract if needed.
Last edited by NCJunglist; 07-26-2012 at 09:14 AM.