I have a 03 cavalier. Just put new waterpump, new thermostat, and new radiator. Still overheating. Acts like there is no waterpump. 0 pressure in any lines, blows cold air unless I rev it up. Heat goes up as the temp goes up. Temp drops so does the heat. Heater core isn't blocked and I did a compression test and got the same numbers across all cylinders. This is my daily and need help ASAP.
03 3rd Gen. #boostloading
its an air bubble dude.. you gotta bleed your lines like you do your brakes.. run the motor with the cap off when the engine is cold and fill it with coolant.. then squeeze the @!#$ out of the rad hoses until bubbles stop coming out of the reservoir. and then fill it up coollent and run it until hot.. if it does it again.. try bleeding again... semi trucks have vent screws on the rad hoses to help with this.. maybe they make a kit for cars..