After installing a re-built 390 in my 73 F-250 and running it for a week or so now I still can't get any heat out of it. It doesn't seem to have any hot water going through the heater core whatsoever. The radiator is new and full, heater core is new, thermostat is new. The heater hoses are hot to a certain point and then not really very warm as you move up towards the firewall. Is this thing air-bound or something? I don't understand how it can't be moving water through the heater core. Help !!

 

Cooling system is full?

Have you tried taking the hoses off and flushing the heater core out to ensure its not plugged up?

 

I must be going crazyy.. don't 73s still use a cable-operated heater valve mounted on the right inner fender? Did your cable slip off?

 

heater core was new about 4 yrs ago. System is full. I guess I could disconect the hoses and either blow some air through it or pump some water through it

 

no cable operated valve on this truck. I've seen those, my 1960 F-100 4x4 has one

 

Park your truck on a tail low place or put the front end up on some metal car ramps. Get the front end up higher that the back and open the radiator (take the cap off) start it, let it idle till the thermostate opens and it should burp the air.

Did you put the wrong intake manifold gasket on and cut off a water port? I'm am spit balling that idea. Sure the water pump is good?

Clogged heater hose lines?? Did you get the block flushed out during the rebuild? Thermostat is for sure the correct one and installed correctily, it happens.

 

if they are warm by the engine, and cooler and the firewall, sounds like something isn't flowing.

 

Does this truck have any sort of vacuum-operated shutoff valve in the heater core supply line? I agree with the advice to try flushing the core. In your first post you said the heater core is new; in your second post you said it's 4 years old. That's not new.

 

This truck sat in my garage for the past 4 years so the parts were all new then. Thanks everyone for all the great suggestions - I'll try them and see how it goes.

 

Workaholic was right. Parked the truck on a hill with the front end elevated, opened the radiator, started it up and within a few minutes it "burped" and I had heat. Thanks very much !!!

 

Awesome, I love to see an easy fix.

More than that, I love it when the OP posts that the problem is fixed and how he/she did so.

Congrats.

 

Agreed, usually we're left hanging after giving advice. Thanks for updating us and congrats on fixing the problem.