HI- just installed new water pump, hoses, new thermostat, new belt, radiator was checked over and is fine, put the new thermostat in pot of boiling water and watched it open, then close after removing so I know it is good. car now overheats immediately (like within 2 or so minutes), so I have not driven it longer than that until I figure this out. The temperature sending unit is new, it isn't the gauge because its the same thing with either of 2 gauge clusters I have. I have heard about the possibility of 'air lock' when refilling the system after draining, and people have mentioned bleeding the system either by a bleed valve on the thermostat housing, or at the expansion overflow tank- my car has neither. Others have mentioned cracking the hoses at the firewall or getting the front of the car raised, or raising one side of the car while filling to eliminate air in the system and completely fill with coolant, any suggestions?. Am I also correct in thinking the thermostat can only be installed one way? Any tips would be appreciated- thanks! P.S. as can happen, I broke off 2 of the bolts on the thermostat housing cover when removing it. I simply used a carbide drill bit to drill completely through what was left of the remaining broken bolts, then continued drilling down all the way through the base of the t-stat body. Then I filed the body carefully to get 2 flats where I could use through bolts with nuts and lock washers (plus some loctite) on bottom works great.