Ok so i put 3,000 miles on my rebuikt FE390 69 F250 C/S i have been paranoid since the P O got it hot and cracked a head that needed to be replaced im running a 180 thermostat and i put a pusher fan infront of radiator that actually cools the water after shut down . Im not sure if center on the factory gauge between C and H is normal operating temp ?
i put a plug at first were the heater return hose would go and plug where water pump heater port was at start up it would get hot fast maybe i did not let the thermo stat open and watch the temp go down but i would shut it down right sway .
My solution was to loop the ports together did it work yes only now it takes 10 min to warm the truck up i cant see how me plugging those ports could had caused any overheating at all makes no sense has any one ran with these ports plugged ????


Pic of them looped together i have 1 temp gauge at thermostat and 1 factory location.

 

1. Essentially i think whats happening with them looped is as the water flows through the heads and comes out the front port through the intake to thermostat with the ports looped its pushing water into the heads and mixing the cold water from the heater port going in and the hot water coming out thats why i think it takes 10 min at start up to get hot 🔥 this cant be the rught way to do it .

 

If you are concerned about overheating, then leave the heater core connected. If the truck gets hot, you can always turn the heater on and cool the engine off in an emergency.

The heater line will have a shut off valve with a control cable to close it. So this shuts that hose off. Therefore, capping off either/both ports is perfectly fine.

The factory gauge is not accurate and never supposed to be super accurate. It is more or less a hot/cold type light. Your installed sensor in the thermostat neck should be moved to the heater return fitting. Otherwise you are just checking the cold return temp, and not the engine temp. So when the thermostat is closed, the sensor is only measuring your radiator.

Fans: If you have the factory fan, then it should cool just fine. Installing a "pusher" fan in front of the radiator may reduce the airflow more than help (but probably help at stop lights). I suggest a good quality Cold Case radiator if you really want to fix the issue.

 

Thanks for the reply i guess im just looking for assurance that plugging both ports up will not cause overheating and i really cant see how it woukd like you said ....looped like i have it its just like having the heater on its going from the port on water pump back into return on manifold plugged be just like i turned heater off i didnt put a heater core i have the big ugly factory A/c unit and it uses a special core i have yet to find it .

 

Don’t loop them, install plugs.

your temp gauge is behind the thermostat. It’s better to put the sensor in the stock location in the manifold. A stuckmor blocked thermostat would show you temps cooler than what is actually happening.

a “pusher” fan isn’t as good as a puller, and most electric fans aren’t as good as the stock fan. Make sure you have a fan shroud and use the stock fan.

Use a temp sensor gun and point it at your radiator as the engine warms up. If there are any cold spots then it might be clogged. If that’s the case Either have a radiator shop clean it out or buy a new radiator. You might be able to clean it out yourself with a pressure washer.

 

There could have been a blockage somewhere. If the cooling system hasn’t been maintained, I would flush it out with distilled water until it runs clear. Then add coolant for a 50/50 mix.