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Clutch fan

5.9cummins

NAXJA Forum User
Location
McCleary WA
Should I replace it with the stock clutch fan or get a flex fan.

On a side note I was thinking about running dual electric and I know it has been covered many times, but I never did see if water and mud was an issue with the electric fans.
 
If you plan to put an engine driven fan in, I suggest a flex fanmounted solidly to the pulley. If you want to go electric, I haven't heard of anyone having problems in water or mud. Most people use a switch to turn the fan off before water crossings.
 
I ran a flex fan for a while. It made way too much noise. It sounded like a jet engine at speed.
 
Ya, they are noisy. But they move a TON of air. I have one on my fullsize.
The only problem I have read about is water crossings or deep mud might take it out, since there is no clutch to allow slippage. If you stay dry then run a flex fan your cooling system will thank you.
 
I have a question regarding the flex fan. I have had problems in the past with fan clutches going bad so I mounted my stock fan on a solid mount adapter from Summit racing and it moved alot of air but was noisy, and took alot of horsepower to run on the highways not to mention the gas mileage dropped big time. I can live with the noise but how does the flex fan do at speed. Do they take alot of enginer power to turn. And how do they affect gas mileage. Thanks.
 
desertrandy said:
I have a question regarding the flex fan. I have had problems in the past with fan clutches going bad so I mounted my stock fan on a solid mount adapter from Summit racing and it moved alot of air but was noisy, and took alot of horsepower to run on the highways not to mention the gas mileage dropped big time. I can live with the noise but how does the flex fan do at speed. Do they take alot of enginer power to turn. And how do they affect gas mileage. Thanks.

On my Fullsize(GMC 5.7l) I havent lost anything. The flex fan is alot lighter than the factory fan, so it probably improved power(cant tell though). Haven't noticed a difference in gas mileage either. Also the flex fan at idle pulls a ton more air than stock.
 
desertrandy said:
I have a question regarding the flex fan. I have had problems in the past with fan clutches going bad so I mounted my stock fan on a solid mount adapter from Summit racing and it moved alot of air but was noisy, and took alot of horsepower to run on the highways not to mention the gas mileage dropped big time. I can live with the noise but how does the flex fan do at speed. Do they take alot of enginer power to turn. And how do they affect gas mileage. Thanks.
The flex fan flattens out higher RPM and doesn't require much power to turn. At speed there is already alot of air flowing into the radiator so the flex fan doesn't use that much power.
 
jeeperjohn said:
The flex fan flattens out higher RPM and doesn't require much power to turn. At speed there is already alot of air flowing into the radiator so the flex fan doesn't use that much power.

X2. on my wifes jeep you can hear the fan when she first gets on it due to the nice big blades, but then they flatten out as the rpm goes up and then you can't hear it anymore. i'm also running her flex-a-lite fan on a brand new fan clutch. i wanted the function of the flex fan, but not the constant drag of the solid spacer. so far running almost 4 years with that setup and her temp has never once moved over 200 no matter what we put her jeep through.
 
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