direct drive flex fan?

Hey guys, I was recently talking to my buddy about fan setups, he tossed a V8 into his CJ and instead of running a clutch fan he eliminated it and uses a direct drive plastic flex fan. This fan is extremely light weight and very flexible

I know if I run in deep water it increases the chances of the fan being pulled into my rad, I however do not plan to run in water that is that deep because at that point there are a bunch of other things I have to worry about other then my rad getting eaten by the fan.

This flex fan must only weigh 1lbs max it's ridiculously light. Would I be causing any harm running in a direct drive configuration? I realize on the highway the fan will "free spool" if it were on a clutch system but this fan is such a reduction in centrifugal weight I don't see it being too much of an issue causing extreme drag?

The only reason I am asking, I replaced the clutch fan with a hayden unit and it still overheats when I go play in 4lo. I by-passed the e-fan and with it running I do not have an fluctuation in temps but I would like to get this issue under control. Would it be stupid to run a flex fan with a clutch and change out the metal fan (if direct drive is a bad idea - I am thinking the flex fan might be able to pull more air)?

Still losing Hp turning it. I'd run a clutch fan or even better go electric and forget it. There is a reason the OEMS totally got away from engine driven fans.

In the perfect world, the taurus fan would be my option A however every install I have seen is a butcher job

there are several aftermarket fans that will work. It's not like the little 4.0's are that hard to cool. Try cooling a big block in a Monza. After that these things are no problem lol.

94CountryXJ said:

....,Try cooling a big block in a Monza. After that these things are no problem lol.

Click to expand...

Ah, sweet memories, the Monza,...

The flex fans work well in the CJ mainly because there is no problem with rad. clearance. The engine bay was lengthened for the 4.2L, so when they put a V-8 in there, there's lotsa' of room. 3"-4"from the fan to the rad. isn't usual with a V-8.

XJ with a 4.0 is a different animal. I don't know if you noticed, but the flex fans are deep. The blades are about 1 3/4" thick stationary. By the time you space it forward enough where you're not hitting engine components you're not going to have much clearance, and they do move around.(they pull forward 1/2"-1" at higher RPM.

Here's the kicker. At idle, they don't pull much more air then the stock fan. If there's a problem with the cooling system, a flex fan won't solve it.

In an XJ, you're better off sticking with the stock clutch fan/switched electric, or going to dual electrics.

Water would be a problem but alot of the older style cars (hell, even up into the late 70's or so I have seen) use direct drive fans with METAL blades. Apparently they don't have any issues at highway speeds.

I went all electric in my XJ. Ditched the clutch fan. Hayden clutches are junk from my experience though, go to a junkyard and pull a OEM clutch fan off of a newer Jeep with the least miles you can find and see if that fixes your problem.

But yes, it does seem like automakers are steering away from clutch fans. Well, any FWD will have electric fans, obviously. But now even most RWD sedans have electric fans.

However it seems for heavy duty trucks and vans they are still sticking with clutch fans.