FAN UPGRADE COOLING/OVERHEATING

[Torinojts]

I have not been worrying about cooling since it is winter time here and I do not drive my truck when there is salt present on the road. But now it is getting close to spring I got to thinking about how hot my truck runs when pulling anything. I know the cooling systems and fans have been beat to death on here but I ran across something that should work. I found a couple fan blades on the Horton website. 994559507 is a 22" fan 2.45 pitch 12 blade with a CW rotation. 995550502 21.65" fan 3.62 pitch 9 blade CW rotation and a 993584503 & 993584501 22.99" fan 3.65 pitch 8 blade. will have to do some measuring on front and back spacing but one of these should work and are available. I did find a couple 23.62" blades that may also fit. All these blades listed are nylon and lighter than stock. The only thing with trying one of these fans is will the viscus fan clutch slip, or lock since they should move more air. So I got to looking again and found that the DT466 in certain years ran an electric 12v fan hub, same thread pitch 1.25-16 UNF 28 LH as our IDIs use. There are also several options will have to get more specs on them. Horton part numbers 996127 is available on eBay right now for $650. other options maybe 996135, 996140, 996135. There is also a 996042 that has a flange style mount, possibly able to retrofit this to where the fan belt pulley mounts to the water pump. anyone ever look into these options? I did email Horton on the listed items and they are available.

 

[Cubey]

A new direct replacement Motorcraft fan clutch (and thermostat) on my motorhome instantly dropped the water temp by 10-15*F. The old clutch was weak but did work some. Keep your A/C off on steep hills to avoid excessive heat.

 

[Torinojts]

I have tried two different fan clutches along with the original one. I can never hear the fan come on and it will over heat if I let it. I did not try an original (new) Motorcraft however. I would like one I could wire into a fan stat.

 

[Cubey]

I have tried two different fan clutches along with the original one. I can never hear the fan come on and it will over heat if I let it. I did not try an original (new) Motorcraft however. I would like one I could wire into a fan stat.

I got my Motorccraft one from RockAuto in 2019 as a "closeout" deal. I kept the original as a spare. Some people drill into it and put in screws so that it's always locked in and turning full blast.

 

[Torinojts]

I thought about that but I do not want it on full-time. I removed the spring and tightened it up thought that would help but it did not. I do have a new Motorcraft thermostat in it and I had the radiator disassembled and the core rodded out

 

[IDIBRONCO]

Some people drill into it and put in screws so that it's always locked in and turning full blast.

I was going to suggest that too.

 

[IDIBRONCO]

Torinojts here's another thought. Could you install a pusher style electric fan? That way it wouldn't have to be working until you really needed it. I don't know if that would help you or not. It's just an idea to gain some extra cooling with your current set up.

 

[Torinojts]

Torinojts here's another thought. Could you install a pusher style electric fan? That way it wouldn't have to be working until you really needed it. I don't know if that would help you or not. It's just an idea to gain some extra cooling with your current set up.

I thought about that as well, but if I decide to put A/C on, which I plan on doing this summer I will not have room

 

[Noiseydiesel]

Coolant is how old and has what amount of water wetter in it?

 

[Torinojts]

coolant is green conventional 50/50 mix with purified water and Cummins DCA additive added

 

[DrCharles]

Question: Do you know it's overheating (do you have a temperature gauge with graduations, checked against boiling water temp at your elevation)?
I once had a car indicating overheating... changed t-stat, checked radiator, everything. Turned out to be a bad temp sensor

 

[Black dawg]

Had overheating issues for years (7.3 maxxed pump and intercooled). Never could hear the fan regardless of clutch used or locked solid. Ended up pulling a load with another 7.3 truck of mine and as soon as it started to get warm.....I could hear the fan and it was loud. Found that the fan blade on my overheating truck was slightly different than the other truck (different part number). Ended up taking that same part number blade off of a parts truck, and it made a huge difference in cooling performance, and it was noisy when engaged. Now when the fan is going, you really have to try to get coolant temps up vs always driving by the gauge before.

I wish I still had that blade, it had an 88 or 89 part number.

 

[Torinojts]

Question: Do you know it's overheating (do you have a temperature gauge with graduations, checked against boiling water temp at your elevation)?
I once had a car indicating overheating... changed t-stat, checked radiator, everything. Turned out to be a bad temp sensor

It is defiantly getting hot. I have a good quality digital temp gauge that reads in increments plus I can switch it so it reads out the temp. I compared it with a temp gun and it is on the money.

 

[DrCharles]

OK, good to know, that eliminates the uncertainty Just how hot is it getting, and when?

So... either you don't have enough airflow, not enough radiator capacity, the water pump isn't pumping, or making too much heat!

Airflow at highway speed is not the problem on our trucks (the fan is basically along for the ride above 35 mph anyway). If it's overheating on the highway, then you can rule that out (unless your fan blades are pitched the wrong way so it's pushing back instead of pulling).

If it overheats at slow speed, I also recommend installing a locked fan as a test.

Another possibility is that the impeller on your water pump has come apart or is freewheeling on the shaft. Unusual but quite possible. Thermosiphoning will only eliminate small amounts of heat (John Deere 2-cylinders didn't get water pumps until the 1950's when the engines became more powerful).

Keep us posted, we'll get this figured out Just remember that adding a/c will make your overheating problem worse, so fix that beforehand!

 

[Torinojts]

I have a new water pump and a Motorcraft thermostat. I did remove the check valve in the t-state housing as well. I used a vacuum filler to fill the cooling system, so no air traps.

This engine is in a 75 Ford with a pretty big bumper on the front, possibly not enough air flow at highway speeds??