No there wouldn't be any smoke. Do you have warranty on the truck still??? They can do a sniff test at your overflow, but that pressurized upper rad hose or overflow cap being super pressurized is a dead give away. It will either be the sleeves or gaskets with gaskets usually getting the nod 7 times out of 10. Good luckYes ,there is alot of pressure , and the coolant seems to be cool.would there be any smoke in this situation?
chopking,Truck gets up to normal operating temp, but the heater blows cooler than normal.
And then when sitting at an idle, the heater goes cold, hold the throttle down a bit and it warms up again. Is this the thermostat or something else?