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the importance of the clutch fan


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13 replies to this topic

#1 soobie_newbie67

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Posted 01 June 2011 - 02:04 PM

i used to just take out the clutch fan and put in an electric fan. i put my clutch fan back in by reccomendation from 1 person on here and my grandpa. i dont remember who it was that told me to put it back on but i thank you. the electric fan i put on was a stupid idea. it was a 12 inch fan and it couldnt keep my Subaru damn near as cool as the clutch fan. im happy i got it back on before it gets really hot next week.

its a 1988 Subaru GL-10 Turbo.

#2 skishop69

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Posted 01 June 2011 - 02:14 PM

You actually don't need the fan clutch if you have the correct size fan, wired correctly so it is temp controlled. I pulled mine from my 87.5 XT GL10 and have had no issues at all. Buy a cheap, non-air-moving chinese POS and you're going to have issues. These cars are notorious for heating up. If yours heated up just because you switched to electric, you might want to be looking at your rad.

#3 El Presidente

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Posted 01 June 2011 - 02:39 PM

Electric fans are better than a mechanical fan clutch hands down...your not using a big enough fan or not enough of them. Fan clutches create a lot of parasitic power loss and switching to a electric fan will usually increase throttle response, and depending on the fan and alternator, you may see an increase in HP and MPG's. The big advantage is controllability...you can set exactly when your fan comes on based on coolant temp, not air temp. You can set them for low, med and hi settings, manually click them on when you want, set a "delay off" so they keep running even thought the car is off, and if you have two fans, you can make them operate independently. Sticking with the mechanical clutch fan is the safest route, but not the best.

Also, if your an offroad guy, you can turn your fans off before fording deep water so your fan blades don't get sucked into the radiator. Buddy of mine did this on his ranger a couple weeks ago in about 3' of water.

#4 soobie_newbie67

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Posted 01 June 2011 - 02:59 PM

Electric fans are better than a mechanical fan clutch hands down...your not using a big enough fan or not enough of them. Fan clutches create a lot of parasitic power loss and switching to a electric fan will usually increase throttle response, and depending on the fan and alternator, you may see an increase in HP and MPG's. The big advantage is controllability...you can set exactly when your fan comes on based on coolant temp, not air temp. You can set them for low, med and hi settings, manually click them on when you want, set a "delay off" so they keep running even thought the car is off, and if you have two fans, you can make them operate independently. Sticking with the mechanical clutch fan is the safest route, but not the best.

Also, if your an offroad guy, you can turn your fans off before fording deep water so your fan blades don't get sucked into the radiator. Buddy of mine did this on his ranger a couple weeks ago in about 3' of water.


well, im not offroading anymore seeing as last time i did, i found water in the rear diff. plus, i notice no power difference at all with the clutch fan vs the electric. i kinda already have it figured out that im gonna use the clutch fan during the summer and the electric one during the winter.

#5 soobie_newbie67

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Posted 01 June 2011 - 03:01 PM

You actually don't need the fan clutch if you have the correct size fan, wired correctly so it is temp controlled. I pulled mine from my 87.5 XT GL10 and have had no issues at all. Buy a cheap, non-air-moving chinese POS and you're going to have issues. These cars are notorious for heating up. If yours heated up just because you switched to electric, you might want to be looking at your rad.


dont worry. its not a chiner pos. it even says made in usa on it. it a 12 inch 2150 CFM fan. my grandpa had it (well them, he bought 2) in i think 1998 for a RV we had. he wanted to eliminate the clutch fan cause of how loud and noisey it was, but the 2 of them together couldnt keep the it near as cool as the clutch fan. summer is almost upon us so im not gonna change anything back for the time being. i dig back into it during winter when i dont have to worry about overheating so much.

#6 El Presidente

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Posted 01 June 2011 - 03:49 PM

If you do it right, electric fans will be better for ANY situation. If your concerned with noise, that isn't your fan clutch unless its squeaking, which means they're dying. The noise has to do with the shape and attack angle of your fan blades. The ones that spiral out are generally the most effiecient and the most quiet. The ones with the square blades make more noise, but move about the same air.

Nothings free including HP. When you put an electric fan in, your just moving the drag from the fan clutch to the alternator. The HP and performance gains are made in the better efficiency of the alternator and fans. The more air it moves per amp the more efficient it is. If you put too much strain on the alternator you can see less HP and performance. Everytime I've ditched clutch fans, I've upgraded alternators.

To be on the safe side, for a constant running fan, you want at least 30 amps over stock. Not all alternators are created equal either, different models "switch on" at different RPM's and different models have different power curves. I'm planning on putting a 140amp CS-144 in my rig. They produce a lot of amps at low RPMs...IIRC 70amps at around 700-800 RPM

#7 soobie_newbie67

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Posted 01 June 2011 - 09:31 PM

If you do it right, electric fans will be better for ANY situation. If your concerned with noise, that isn't your fan clutch unless its squeaking, which means they're dying. The noise has to do with the shape and attack angle of your fan blades. The ones that spiral out are generally the most effiecient and the most quiet. The ones with the square blades make more noise, but move about the same air.

Nothings free including HP. When you put an electric fan in, your just moving the drag from the fan clutch to the alternator. The HP and performance gains are made in the better efficiency of the alternator and fans. The more air it moves per amp the more efficient it is. If you put too much strain on the alternator you can see less HP and performance. Everytime I've ditched clutch fans, I've upgraded alternators.

To be on the safe side, for a constant running fan, you want at least 30 amps over stock. Not all alternators are created equal either, different models "switch on" at different RPM's and different models have different power curves. I'm planning on putting a 140amp CS-144 in my rig. They produce a lot of amps at low RPMs...IIRC 70amps at around 700-800 RPM


no, the noise is nothing bad at all. its the sound of air as the fan starts to kick in. anything with clutch fan does it, im pretty sure you already know though so im gonna save my wind.

if you could make links for me for the ************ i need that would be great.

#8 El Presidente

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Posted 01 June 2011 - 11:17 PM

Ok, I thought you didn't like the noise of the electric fan....Fan Clutches shouldn't make any noise at all, so if yours is, just get a new one or upgrade to electric. Noisy clutches eventually just stop working so beware, especially on a ea82T..

What links do you need? Your sentence got censored out.

#9 soobie_newbie67

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Posted 02 June 2011 - 12:56 AM

Ok, I thought you didn't like the noise of the electric fan....Fan Clutches shouldn't make any noise at all, so if yours is, just get a new one or upgrade to electric. Noisy clutches eventually just stop working so beware, especially on a ea82T..

What links do you need? Your sentence got censored out.


no, ugh. how do i explain the noise. you should know. clutch fans are quiet, as the engine heats up the clutch stops slipping, which in turn makes the fan start spinning faster, which in turn is pulling more air through, and it makes a noise just like an extremely large fan. you know, like you hear from semi trucks, both our trucks do it, and our motorhome does it while going down the highway. all clutch fans make the same noise.

links: i said the S word, so it blocked it out. links to some good fans, i dont need a switch, i already have a temp sensing adjustable one.

#10 El Presidente

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Posted 02 June 2011 - 03:01 AM

Gottcha:grin:

I've run perma-cool fans on drag cars when I was younger, just give'em a call and describe to them what you have going and they'll set you up, but it's $$$. I usually use JY fans on offroad rigs(which is all I build anymore), because they tend to give out when subjected to constant dirt and abuse and I don't like dropping $150+ bucks when something that costs $20 does the same thing. I used to have a link that described CFM and amp draw of stock fans, but I lost it a while ago. I know a couple EA82 guys have used a EA81 fan where the mech. fan is and left, or installed, a EA82 A/C fan on the passenger side. That gets you two electric subaru fans, but its a tight fit from what I hear.

If your looking in the JY, look for small to midsized cars with cramped engine bays and lots of accesories, like A/C. Early 90's Dodge Neons w/ A/C move a ton of air and each fan pulls about 22amps after startup IIRC. They have spiral blades to reduce noise too. Theres not a lot of room in a subaru, so you might want to consider a pusher fan that would mount in front of the radiator.

If you like the look, louvered hood vents can really help cool your motor too. I've personally seen under hood temps drop 40 degrees and coolant temps drop 15-17 degrees witht he addition of a couple hole in the hood.

#11 MilesFox

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Posted 02 June 2011 - 10:05 AM

I always kept the clutch fan for simple mechanical relaiability. If your electric fan or thermoswitch fails, andd you get stuck in traffic, there goes your HG.

Electrics, i suppose, can be more effective. The lutch fan works best when the shroud is present.

Who said you can't use an electric fan WITH the clutch fan. Any 'parasitic power loss' from the clutch fan is inconsiderable, considering it is already there by design, and any gains by removing it does not benefit as much as 100% reliability with a mechanical fan.

Give or take either way

#12 soobie_newbie67

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Posted 02 June 2011 - 02:07 PM

I always kept the clutch fan for simple mechanical relaiability. If your electric fan or thermoswitch fails, andd you get stuck in traffic, there goes your HG.

Electrics, i suppose, can be more effective. The lutch fan works best when the shroud is present.

Who said you can't use an electric fan WITH the clutch fan. Any 'parasitic power loss' from the clutch fan is inconsiderable, considering it is already there by design, and any gains by removing it does not benefit as much as 100% reliability with a mechanical fan.

Give or take either way


thank you! someone who understands

#13 Uberoo

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Posted 02 June 2011 - 02:44 PM

I have two fans on my offroader.Both came from a 90 nissan pulsar.I had to modify the frame of the fans to fit in front of the radiator.I dun't know how much air they push but its alot.I can turn them on at 35 mph and still cool the car down.

#14 El Presidente

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Posted 02 June 2011 - 09:57 PM

I always kept the clutch fan for simple mechanical relaiability. If your electric fan or thermoswitch fails, andd you get stuck in traffic, there goes your HG.

Electrics, i suppose, can be more effective. The lutch fan works best when the shroud is present.

Who said you can't use an electric fan WITH the clutch fan. Any 'parasitic power loss' from the clutch fan is inconsiderable, considering it is already there by design, and any gains by removing it does not benefit as much as 100% reliability with a mechanical fan.

Give or take either way


I don't consider a clutch fan %100 reliable at all simply because theres nothing physically connecting the fan to the water pump. I've had clutch fans go out far from home and its a pain in the @ss, because it can be hard to diagnose. When ever I've done an electric fan upgrade, I make sure theres redundancies to prevent a complete failure. All my fan upgrades used two fans on separate thermal switches and timers and were independently controlled from each other with a manual override for each. I also made sure that the vehicle can run on one fan and doesn't need both to stay cool under normal conditions so if I lose one, I can still make it home.

Parasitic power loss is just cages horses and if you don't want to let them out, thats up to you. There isn't a ton of drag in a clutch, but little mods here and there certainly add up.

I agree though that its give or take either way, just depends on what your needs and priorities are.

Now a fan with NO clutch IS %100 reliable, but the fan needs to be designed for it. I've tried just removing the fan clutch on one of my old trucks and I had to crank the curb idle up just to keep it running. Sounded like a hurricane under the hood and the motor never really warmed up.




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