[Sonny's towing]

The truck takes 20 min. to warm up then I get on the hi-way and cool air no heat let it idol and the heat comes up. New water pump thermostat radiator and steal no heat!

 

[grassfarmer]

no heat from the radiator

I will tell you what others on this forum told me. If you replace your thermostat it MUST be a Ford replacement and nothing else. My 7.3 was exactly like what you described and when I replaced the thermostat with the correct one I get heat in a short period of time, the engine never over-heats on long pulls, etc.

 

[Sonny's towing]

No heat

I put in the thermostat from ford

 

[samksmith]

You probably have air bubbles in your cooling system. Common cause for no heat after flush/fill. Let it run with the cap off until you don't see the radiator burping air bubbles. Keep a container of the 50/50 to add if needed.

 

[cdnsarguy]

Ensure the overflow tank is 3/4 full and the rad cap is sealing correctly... if it has a deep groove in the seal replace it....... also check the small hose to the overflow tank.. it can get full of crud and seal off in the tank...... also ensure there is a very good seal at the rad filler end.

The rad is supposed to be full cold....... when it heats up it pushes excess fluid into the O/F tank..... when it cools it sucks back what it needs to keep it full....... it does this all the time.

If you place a Preston T fitting with a cap at the highest point of the return heater line (when held up about 1/3 of the way from heater core to water pump) you can drain any air by cracking open the T fitting cap with pressure in the rad.

If you have never done it removing the heater hoses and flushing the core both ways is a great problem solver..... we use a garden hose to flush then an air hose to assist with cleaning.... do this in both directions.