I need some input please. Truck started overheating about a month ago and I’ve been working on it since. Changed the thermostat - no change. Changed water pump - no change, but started blowing cool air when on heat. Changed bottom radiator hose and both bypass hoses on water pump - no change. Hose running from heater core to intake manifold busted, changed that - no change. Put in a new thermostat sensor - no change. Switched and put old water pump back on, took longer to overheat and started blowing heat inside the truck. Put on a new idle air control valve - still overheating. Is there any other possible thing I could look at?

 

Got to make certain to get ALL the air out of the cooling system, period.

 

we burb the hose every time we change out the coolant

 

Is there any white smoke coming out of the tailpipe? You may have a blown head gasket. Check for air bubbles in the radiator. A bad intake manifold gasket will also cause over heating. Make sure you don't have any leaking, corroded freeze/ expansion plugs in the block or heads, of course, this is obvious by doing a manual inspection. Finally, check the oil dipstick for any signs of water in the oil. You will see a milky oil if there is water in there. Just some things to check.