Upgrading to clutch fan, brand recommendations?

SheepnJeep

Adventurer
Hey folks,

I'm considering swapping my truck fan from a straight no clutch fan to a clutched unit. Just looking to improve MPG for better range etc. as the vehicle mostly gets used for longer road trips. Might help with faster warmup as well(?) Eventually the fuel savings will pay for the clutch but that's not the main concern. Does anyone have any recommendations on a good clutch unit to use? Not sure if I should go straight for an autozone cheapy or if there are higher quality options that people have had good luck with. My local Ford dealer didn't have much to say about it.

Truck is a '73 F100 with an inline six.

Thanks!
 

(none)

Adventurer
Which inline 6? The 300 came with a clutch fan in later iterations I believe, I'd think you could use one of those. Id think any decent aftermarket brand will be fine. They are fairly simple.
 

SheepnJeep

Adventurer
Oops sorry it is a 240 ci. Same block and stuff as the 300 ci. I'm guessing a 300 piece would work fine.

I hesitate to go electric as the truck has a tiny 30 amp alternator. Basically I would need to put in a bigger alternator and set up a auxiliary fuse block with robust enough wiring to handle a big fan. I also worry that even the best electric fans don't move enough cfm for towing. Plus if the clutch fan pooches out I can just unbolt it and go back to the stock unit. Might have enough room for a stock fan to go back in place behind the electric unit if it did die though.

Thanks for the replies so far
 
Hayden has been around for decades. I'd get a standard thermal unit. Need a good shroud too, make a all the difference. Fan should protrude two thirds I to the shroud. The better its sealed against the radiator the better it works.
 
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ExplorerTom

Explorer
My experience:
I recently replaced what I can only imagine was the factory fan clutch in my 2000 Expedition. It probably had around 200k miles on it. I replaced it with a Hayden. It seemed to be engaged more when cold than the factory clutch. But it worked. Drove around for like 30k miles with no issues.

Then I drove home from Dillon, CO to Denver. This route quickly climbs a very steep grade and I was doing the speed limit 65 mph) for the 4-5 miles all the way up to 11,000 feet or so. The rest of the trip is mostly downhill. When I got onto city streets, I noticed my clutch was fully engaged just accelerating from a stop light. Sounded like a 737 taxing. I figured maybe it needed to cool down. The next day it was still fully engaged. All the time.

I replaced it with a NAPA brand clutch. And then a couple months later, I repeated that trip. And the same thing happened.

So I went the efan route. I haven't driven that same route, but I've been liking the efans.

I wondered if I had got a Motorcraft clutch, if it would have held up better than the aftermarket clutches.
 

SheepnJeep

Adventurer
Hmm interesting so a big hill climb potentially killed off two fan clutches. That's not great news. I can look harder into doing electric fans, but it will be a whole thing to get them installed. I have noticed that there are electric clutch fans out there, no idea if I could get one for my application yet. It would be pretty cool to have a thermostat and a override switch for fan-on if you noticed temps were climbing and the fan wasn't running.

Thanks for the replies so far folks
 

ultraclyde

Observer
My experience:
I recently replaced what I can only imagine was the factory fan clutch in my 2000 Expedition. It probably had around 200k miles on it. I replaced it with a Hayden. It seemed to be engaged more when cold than the factory clutch. But it worked. Drove around for like 30k miles with no issues.

Then I drove home from Dillon, CO to Denver. This route quickly climbs a very steep grade and I was doing the speed limit 65 mph) for the 4-5 miles all the way up to 11,000 feet or so. The rest of the trip is mostly downhill. When I got onto city streets, I noticed my clutch was fully engaged just accelerating from a stop light. Sounded like a 737 taxing. I figured maybe it needed to cool down. The next day it was still fully engaged. All the time.

I replaced it with a NAPA brand clutch. And then a couple months later, I repeated that trip. And the same thing happened.

So I went the efan route. I haven't driven that same route, but I've been liking the efans.

I wondered if I had got a Motorcraft clutch, if it would have held up better than the aftermarket clutches.

I've had a similar experience, sort of. I replaced the entire cooling system on my ZJ this spring - water pump, radiator, and of course the thermal fan clutch. At 160k I suspect it was all original parts. The fan clutch that came out didn't feel bad and I wasn't having cooling issues but the WP started leaking, so I was doing the whole system since it's a road trip vehicle in GA. I used quality aftermarket parts, I think the clutch was a either a four seasons or hayden. The clutch initially felt REALLY stiff and the noise from the truck was terrifying. It sounded like a struggling diesel box truck at anything over 1000rpm and my gas mileage TANKED, but it stayed cool. Now, maybe 3k miles later, it's loosened up some. It now sounds like a box truck over 2000 RPM and running at 70mph it's a constant drone. Although it stays nice and cool while moving, it will steadily creep up to overheating if parked and idling. I've never seen the "thermal" fan clutch lock up or change in any fashion even up to 230+ degrees.

I swear the fan clutch is bad, but it's not just plain broken either. Drives fine but it HATES drive thru window lines and SLOW off road crawls.

I'm planning on doing an electric radiator fan and variable speed controller this winter. I could drop the $150 for a factory Jeep fan clutch, but that's half way to a basic electric setup too....of course I'll blow 3 times that on something double-stupid-robust and shiny, but it's probably overkill.

As for power, yeah, a 30 amp alternator will probably need replaced but higher power options shouldn't be too pricey for that truck. Look at the "soft start" type fan controllers too. The main amperage spike is when the motor starts and these use a slow speed start up to minimize the max load on your system. They are more expensive but they can make a lot of difference when your charging system is borderline. The nice thing is there are a lot of options for old muscle cars and your truck is the same basic layout. Big square radiator and plenty of space. If you feel like doing a little basic homebrewing you can source some good fans from the junkyard for cheap. Google 3.6L Taurus Fan or Mark8 fan conversions. You could luck up on a good fan for under $50 and run a Flex-a-lite soft start module for under $200 total if you try hard.
 

1stDeuce

Explorer
I just looked up a '78 F100 with a 300 six on Rock Auto. The link is for the standard duty thermal fan clutch from 4 seasons.
If you're after the most fuel savings, or quietest one, the thermal unit is best, but a non-thermal one is still WAY better than your fixed fan. https://itstillruns.com/difference-thermal-vs-nonthermal-fan-clutches-12246205.html

Click the part number to see the other applications. There are a LOT of them!! Any fan from those applications that will fit your truck will work. Get one off a vehicle with A/C if you want a bit more cooling capability.

I would suggest you go junkyarding and get a fan (and clutch?) from one of those vehicles. The fan dia and total depth of blades to mounting surface should match your truck for best fit. Once you find one that fits, you can replace the clutch for cheap and you're off. You might need the radiator shroud too, depending on the diameter of your fixed fan.

My $0.02 on electric fans:
I do NOT recommend an electric fan for ANYONE anymore, unless there are space or accy drive limitations. I've seen cooked engine computers, had no shortage of vapor lock issues, toasted alternators and v-belts, etc. Plus when mounted with the zip clips through the actual radiator, they usually end up doing damage in the long term. Go with what worked for half a century, don't look back.
 

SheepnJeep

Adventurer
1stDeuce,

I like the idea of a non thermal fan clutch, as I probably could bolt it straight on and not have to worry about adding a fan shroud for the moment. However the fact that they only spin so fast regardless of engine temp may be a little scary when it comes to towing. I'm going to check out the thermal options. I will have to probably source a "make a shroud" kit as I have put a larger than stock radiator in place.

I do sort of wonder about adding a non thermal clutch and a electric fan. That way I could have a smaller capacity fan that kicks in for the bad times and have the simplicity of a non thermal clutch working the rest of the time. Our jeep Cherokee works this way I believe.
 

1stDeuce

Explorer
You have to remember that a large fan spinning at 1800rpm's is probably capable of moving 2 or 3x the air that your four blade fixed fan moves at 4000rpm, where it's mostly cavitating and making noise. Getting a fan off something with A/C will ensure you move lots of air even at the lower RPM's.

Cherokee's do use one small engine driven fan and one electric, but this is mostly due to packaging. The radiator is short and wide, so a big round fan wouldn't have worked well. A TJ uses the same 4.0L, and a big round clutched fan and actually cools better than the cherokee's do in my experience. The radiator surface area between the two is very comparable.

KISS almost always does better in the end, and you can't get simpler than a good size clutch fan. :)
 

ExplorerTom

Explorer
Which all sounds well and good until you realize that cars, trucks and vans have had electric cooling fans for decades. They seem to run just fine on them. Brand new F-150s, from the factory, come equipped with with electric fans- not fans hanging off the water pump.
 

SheepnJeep

Adventurer
Alrighty well I think for my application I am going to stick with a thermal fan and see how it goes. Looks like I can order a "make a shroud" kit for a custom fan shroud, and the clutch for a fan is less than $30. So say about $100 by the time I get all the stuff here. If I could see 1 mpg difference per fill up that would be about 6 percent better fuel economy (I think. 300 miles to a 19 gallon tank now) Not too bad of an improvement for little work. Even if I did 5% better that would be pretty nice over time. I will report back with the results!
 

ultraclyde

Observer
I thought I'd throw on an update - I had an incident where my weirdo fan clutch suddenly started working correctly. It unlocked fully while towing a boat on the interstate and the Jeep was nice an quite even running without OD. Temp crept up to 208 and held there. Got off the interstate and the emp ent up to 213 sitting at a light. Suddenly the engine got loud (fan engaged) and temp dropped like a rock to 195, then the engine got quiet again (unlocked.) I actually like the way that works.

After some other discussions with ZJ guys, the 5.9L versions came with monster electric fans and had a decreased towing capacity because they just couldn't cool as well as the 5.2L's clutch fan. Since boat towing is a thing I've re-evaluated my choices and will be putting on a real Mopar thermal fan clutch.

So, yeah, I'm starting to agree with @1stDeuce
 

1stDeuce

Explorer
Just to be clear, a proplerly designed OE electric fan setup should be able to cool as well or nearly as well a clutch fan. My beef is mainly with using an aftermarket electric fan to replace a clutch fan. The aftermarket fan setup is a pile of garbage generally... First because the fan is usually mounted through the radiator with T strips. Second because it probably doesn't move as much air as the original clutch fan. Third because the on/off strategy is seldom ideal, and results in the underhood temps occasionally getting very high while the fan is waiting to come on. Fourth because most older vehicles have alternators that struggle to put out even 20 amps at idle, while electric fans can draw that much or more all the time. This is hard on the battery, belt, and alternator.

It can be made to work, particularly if using a 2-speed electric fan, where low is on all the time to circulate air underhood, and high comes on when the engine temp gets above normal. But that setup isn't saving you anything, and it's certainly not as simple or robust as a clutch fan.

Hopefully that explains a bit better where I was coming from. Truth be told, I have a Taurus 2 speed fan on our Comanche. The alternator seems to keep up OK, but the fan motor is loud and needs replaced... It was all I could package for cooling with the camaro V6. I have it wired so low speed comes on as soon as you key on the ignition. The fan is kicked into high by the Camaro computer's aux fan output when the engine temp hits 220F. Low is usually enough to keep it cool unless it gets low on coolant, which happens due to the crappy $100 ebay aluminum radiator that leaks... I'm looking for 2.8L S10 that I can rob the TBI setup and front accy drive. When I do, it'll be going back to a regular clutch fan, and I'm sure it'll be better than the electric setup I'm running.
 
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