So my 94 b4000 is still overheating after replacing the water pump. The main two responses to the last post were air in system and possibly headgasket. I purchased the headgasket combustion leak test kit and it came negative and also a spill proof funnel and tried to burp the system. However when letting the car run after heating up the coolant would come to the top of the funnel. It would rise and fall with an upward trend toward rising. Upon shutting off the vehicle it would immediately drop back to within the radiator. Would this be indicative of a clog in the system somewhere or am i just chasing ghosts? no coolant was added and the coolant level did not change at all. I am leaning toward the water pump just being bum.