I just reapir the overheating problem on my 2001 chevy silverado 5.3 2wd. I am still overheating...it is full of coolant...reservour is still at the fill line with GM dexcool coolant. The problem to begin with was the Quick disconnect broke on the heater side. Again It was repaired and still over heating. What could be the new problem

Possibly an airlock in the system,undo the topmost hot hose clip and allow any air to vent.careful its bl...y hot.

If it overheated i would replace the thermostant and gasket, also make sure its full of coolant, after replacing the thermostat you may have air in system so let it run until stat opens it may boil over a little until stat opens then it will **** coolant into block when that happens fill with coolant, you will need to let it idle for a while before new stat opens, hope this helps, good luck, i think the stat went bad the first time it overheated.

You could have a stuck thermostat or an air pocket in the cooling system.