i have a 78 f150 with a 460 and the heat blows ice cold on the highway. is there a better way to plumb the heater hoses for hotter coolant flow? it runs at 190-200 degrees, new heater core, t stat, 4 core radiator with cardboard blocking it and yes it is full of coolant. heat is tolerable in town but at 50-60 mph+ its cold. any suggestions please.

 

Try switching the hoses at the heater core around.
It is possible you have them backwards.
Sounds silly? Yep, but it might work.
The heater core needs to fill from the bottom up, not from the top down to give best heat exchange.

Also check the inlet tubes to see if anything like RTV scraps have come loose and are plugging it up.

Good luck!

 

You might put a restrictor in the line going back to the pump. Your feed line to the heater core should come from the intake before the thermostat housing.

 

thanks guys, i was wondering if the water pump pulled water through the core or pushed it. ill see what i can do.