Making some popcorn. Would anybody like some?

 

I like what was said on no Stat and over heating.
Coolant can also go thru the motor to fast to pick up heat just like to fast thru radiator can't get fid of it.
Dave ----

 

That is a long-standing myth.

The issues is not in the engine but in the RAD.
The velocity of the coolant in an engine or heat source will not affect its ability to shed heat as long as the coolant has the capacity to absorb it.

As the velocity or flow rate of the coolant increases in an engine, the amount of heat that a fixed volume of coolant absorbs from the engine will be decreased since it is in contact with the engine block for a shorter period fo time. But, since the velocity or flow rate is increased the volume of coolant flowed through the engine is increased. The same amount of heat will be absorbed from the engine, now it's just spread across a larger volume of coolant providing the coolant has the capacity to absorb the heat.

The issue is in the rad, if the velocity of the coolant is too high it won't be in the rad long enough to shed all it's absorbed heat, the time needed to shed the absorbed heat in the rad is impacted by several factors, the efficiency of the rad, it's the physical size (volume), airflow impediments, ambient temp, barometric pressure and humidity, Fail to shed ALL the absorbed heat and you will end up in run away and an overheat. Failure to dump just 1 BTU of absorbed heat will eventually lead to an overheat.
If the efficiency of the rad drops due to any of the aforementioned variables the coolant is going to need to be in the rad for a longer period of time to shed the heat it has absorbed. With a higher velocity, it may not be in the rad long enough to do that.

 

The thermostat definitely helped, but didn't cure the issues. I finally decided to replace the fan clutch and when I pulled it out, I noticed that the fan was installed back wards. I can only blame myself, because I replaced the clutch when I first bought the truck. That was on "Oh S%#T" moment. Now she runs at a normal temperature with or without the A/C running. Problem solved.

 

We all have a moment like that just some of us don't tell
So this only over heated when moving or all the time?
I could see when moving as the fan is trying to push air forward but when moving the air is trying to be pushed back.
Thanks for posting what it was as it may help others.
Dave ----
sorry for hi jacking your post with Matt but its not like we went off in left field as it was still some what dealing with over heating.

 

Hey! Do you mind staying on topic here? We had a great flame war in progress, just getting good, and then you go and kill the entertainment with your "problem solved". Criminy, kids these days... What am I supposed to do with all this popcorn I made for the show?

Back to your off-topic fan discovery: Did you ever try the trick of checking the airflow from the fan by holding a rag or piece of paper in front of the radiator? It was suggested in an earlier message, but don't remember seeing if you had tried that.

I also am trying to figure out how the airflow would behave with the fan installed backwards. I wish I had a spare fan at hand so I could hold it up and see. The mental gymnastics are enough to put me over the edge. With the angle of the blades, I think the air would still flow in the same correct direction. However, the blades typically have a healthy curve or camber to them, and that would be wrong relative to the rotation. I think the air would NOT move backwards, but still in the correct direction, but at a much reduced rate. Maybe somebody has a spare fan and they could post pics showing the fan in both positions.

 

FWIW there is a factory HD 7 blade fan out there for these fords. Keeps my 250 cool.

 

Yeah, that was basically it. the fan does blow in the same direction ,but when installed correctly, it moves more air because it scoops due to the shape the blade ends. I did some head scratching too until I noticed the shape. It was a great moment for me. Wished that I had that moment when I installed it the first time.