My '77 F150 currently has a cheap flex fan and missing fan shroud. It still cools sufficiently for where I live, but i'm sure it would overheat if I towed/went off road. What configuration and size of electric fans works well for severe-duty usage?

 

The best possible fan for pumping the maximum amount of air through the radiator would be a "rigid" fan mounted directly to the water pump; however, this style reduces horsepower & mileage and causes additional wear on belts and water pump bearings.

A clutch-style fan with a thermal sensor will pump nearly the same amount, but only when the cooling system needs it; saving wear, horsepower, and mileage. They are also much quiter than a direct drive rigid or flexi-fan. You will notice a big difference in noise when moving slow at fairly high RPM. The only drawback I can see to this style is that the clutch can fail, just one more thing that can go out.

I do not like flexi-fans much except for "jeep" roads where you need maximum cooling at low RPM. If this is where most of your cooling problems occur, then this style is fine. But don't count on them for heavy-towing cooling problems on the hiway. They are designed to pump out only a certain amount of air no matter what the engine RPM may be. They are also quite noisy.

Electric fans just don't put out enough umph to cool a large engine by themselves. They are great however as an auxiliary cooling device in conjuction with the engine-driven fan for extreme conditions. If this is your plan, mount the electric fan on the engine side of the radiator if possible. They are much more efficient when pulling air through rather than pushing it. Electric fans work great by themselves on smaller engines and again for trail-use vehicles where they can be shut off for crossing deep water.

Installing a fan-shrowd will probably give you the biggest improvement in cooling. Some people think they are just guards to protect your fingers or anything else that might come in contact with the fan while the engine is running. Their main purpose is to ensure that all the air the fan pumps comes through the radiator rather than just around it.

To sum things up, if it was my truck, I would buy a heavy-duty thermal fan clutch mounted to a large rigid fan with a shroud installed on the radiator. If that was not enough then I would add one large or two small electric fans mounted behind the radiator with an on-off switch mounted in the cab.

Good luck, I hope this helps.

 

There are two different class electric fans, push type and pull type. I really don't know what is the best, however the rigid type directly mounted to the waterpump is definitly the best. Ford produced diferent configurations 4,5,6 blade fans the shroud is for safety as well as creating a negative pressure for the atmosphere to draw air through. Thermal efficiency occurs when maximum amount of air extracts maximum amount of heat.
I agree with above comments in short by friction type clutch fan and Max out in the blade dept.
Stay Cool Man........

 

So just running an electric fan won't cut the mustard? I was hoping an electric fan would save me the hassle of finding a shroud, and boost my fuel economy. I guess i'll look into a rigid clutch fan instead.

 

Ben:

There’s a lot of good info in the above posts. Like-M is correct when he stated that you want to get the maximum air moving through the radiator extracting the maximum amount of heat. Years ago I heard of a test to determine if you are drawing enough air through the radiator: start your engine and place a standard red shop rag on the front of your radiator. If it stays put then you are drawing enough air, if it falls then you have a flow problem.

There is another rule of thumb regarding your radiator. With your engine off, fill up the radiator and remove the lower radiator hose. The water should run from it with enough force to land at least one foot from the radiator. If it doesn’t then your radiator is clogged and needs to be cleaned/rodded out.

I have a ’68 Mustang with a rebuilt 289. The block is bored .030” over so the cylinder walls are a bit thin. My old rule of thumb was that if it was going to be over 80 degrees outside I wouldn’t drive it because it would run hot. I live in Northern California and the forecast during the entire summer is for more than 80 degrees.

The radiator and fan passed both of the above tests but the engine would still run hot. I installed a 160 degree thermostat and a 4-row radiator but I still had problems on 80 degree days. Mustangs have small radiators so adding the 4-row helped, but not enough. I had a flex fan already installed so I installed a fan shroud (68 Mustangs without air conditioning did not come with shrouds, but those with air did. Shrouds are cheap and easy to install). I also installed a pusher electric fan in front of the radiator with a switch located inside.

I can now drive my Mustang in days up to 90 degrees. There has been a lot of thought and a little work involved, but everything I did added a little additional cooling power and everything combined gave me an additional 10 degrees of ambient air temp. to drive in. This may sound crazy, but I love to drive my Mustang and this gives me a little extra confidence in it. I still carry 4-gallons of water in the trunk just in case.

I just bought a ’71 F30 Camper Special whose 390 wore out. I installed a 400M into it. I am amazed at the size of the radiator and I am curious how well it will cool the 400M. I’m not anticipating any problems merely because the radiator is so large. I’ll know within the next few weeks because I just got it running and registered with DMV.

If I was to remove the mechanical fan from any vehicle and install just an electric fan, I would get the largest and most powerful fan I could find. My preference would be to get a twin fan puller setup for the engine side of the radiator and, if that wasn’t enough, then I would install a supplemental pusher fan on the front of the radiator. I have noticed on my Mustang that the pusher fan turns slowly once I’ve started the engine. This means that it is slowing the air moving through the radiator, thus reducing the effectiveness of the puller fan on the engine side of the radiator. It more than makes up for this drag once I turn it on.

Another avenue to consider is aluminum radiators. They have come down a lot in price from a few years ago and they will cool better than a brass fan. Brass actually transfers heat better than aluminum, but aluminum is stronger than brass so the water tubes in the good aluminum radiators have a larger cross section than the brass radiators so they are able to hold a lot more water in them, thus increasing their ability to cool. They are also much lighter.

Good Luck.

Bruce

 

My latest project is a '71 F-350, not a F-30. Sorry about that typo.

Bruce

 

Bruce, (or anyone)
Any recomendations for a radiator shop in Nor Cal?
The one I've got in my '70 F250 is weeping and a bit green!
Rod

 

If your radiator is still the original, then the radiator shop will probably recommend a re-core due to corrosion and buildup of crap inside. If this is the case, you might be looking at about the same price of a new one. Give Hugh's Factory Direct a call toll free 1-877-384-0396 www.hughs.com. They are located at 8655 HWY 99E Los Molinos, CA 96055. Not sure if they are far enough north for you, but they can ship UPS anywhere. He will need to know more info on the one you have now such as the size of the core (19 1/2 x 26 ???), number of rows front to back (3 ???), AC ???, Auto Trans ???. They also need to know the mounting style. Most of the F350's and F250 4x4's of your year have radiators that mount by bolting toward the rear of the radiator from brackets welded to the front of the truck. The radiators used in F250 2WD's have front mounted brackets that reach out forward and bolt to the front of the truck.

If you want a radiator with a lifetime warranty, ask them if they carry Modine; if they don't, then Radiators Direct 1-800-501-1664 does. They are based in New York, but their quoted price includes shipping costs. I was quoted a price of $255 for a lifetime warranty 4-row Modine for my 1969 F250 2WD. That included shipping to WA.

Just something you might want to consider before having your's repaired by a shop.

 

That's a pretty good price. JCWitney wants $380 shipping for the same radiator. They also have a "ready-rad" brand for $340-350 shipping.

 

I put on twin electrics on my new 351W in my old '82 F150. They allow the engine to run hotter than I think it should in 100 heat, but then everything is hard to keep cool when it's that hot!! I also purchased a new 3-row Modine radiator locally for $180 and that helped a lot.

Slik