Fan Clutch

changingtime · **Posted:** Fri Jul 08, 2011 2:17 pm

I see a lot of posts on bad fan clutches. How does one check to see if their's is bad?

Mine seem to kick on, especially when towing...the fan is humming very loudly...

DOC4444 · **Posted:** Fri Jul 08, 2011 5:06 pm

If you hear a roar when you get a bit high on the temp gauge, you are good. I put in a brand new OEM clutch a couple of years ago and it has never worked, even with the gauge pegged towing up a long hill. I have a Hayden to install now.

DOC

Joe Romas · **Posted:** Sat Jul 09, 2011 6:56 am

A Hayden 2905 fan clutch bolts up and is set to activate at 170f that is pretty close to our 176f stock thermostat opening.
See this thread if your having overheating probles :BANANA:

http://www.jeepkj.com/forum/showthread.php?t=48653

papaindigo · **Posted:** Sat Jul 09, 2011 7:07 am

Go to http://colorado4wheel.com/manuals/Jeep/KJ/ (linked from Sir Sam's NOOB guide page) and download the 2006 FSM. Test procedure begins on page 7-61.

The Hayden is a good replacement clutch if one is needed. According to the Hayden web site it kicks in at about 170 degrees based on air temp off the radiator which Hayden says is about 30 degrees below actual engine temp. From what I can find this means the Hayden will kick the fan into gear right at the beginning of an overheating cycle, which should stop that process in its tracks, as opposed to the factory clutch that, if working, kicks in at a somewhat higher temp.

TJ2 · **Posted:** Sat Jul 09, 2011 3:00 pm

I would think you've already tested it. Towing in the summer (especially if you pull some grades) without overheating sounds like a very effective test.

FWIW, I've never heard my fan 'roar.' I hear it come on. I had Kap's flex fan mod before the Hayden and it never really roared, either. Apparently we hear things differently.

as always, YMMV

warp2diesel · **Posted:** Tue Jul 12, 2011 7:29 pm

Ultimate fix: http://www.jeepkj.com/forum/showthread. ... 653&page=2
My AC even works better and EGT drops faster too.

Squeeto · **Posted:** Tue Jul 12, 2011 7:54 pm

warp2diesel wrote:

Ultimate fix: http://www.jeepkj.com/forum/showthread. ... 653&page=2
My AC even works better and EGT drops faster too.

Your Hayden kicks the fan in at 170F?
Okay for the summer but come winter, you may take a long time getting the engine up to operating temperature.

I know that the thermostat is supposed to regulate this but from my experience this winter with all the stat mods, the engine looses a lot of heat on its own. Kicking in a fan at 170F may only aid this loss.

WolverineFW · **Posted:** Tue Jul 12, 2011 8:15 pm

Squeeto wrote:

warp2diesel wrote:

Ultimate fix: http://www.jeepkj.com/forum/showthread. ... 653&page=2
My AC even works better and EGT drops faster too.

Your Hayden kicks the fan in at 170F?
Okay for the summer but come winter, you may take a long time getting the engine up to operating temperature.

I know that the thermostat is supposed to regulate this but from my experience this winter with all the stat mods, the engine looses a lot of heat on its own. Kicking in a fan at 170F may only aid this loss.

I believe it is 170F air temperature, not coolant temperature. Coolant temperature should be higher.

warp2diesel · **Posted:** Tue Jul 12, 2011 8:55 pm

WolverineFW wrote:

Squeeto wrote:

warp2diesel wrote:

Ultimate fix: http://www.jeepkj.com/forum/showthread. ... 653&page=2
My AC even works better and EGT drops faster too.

Your Hayden kicks the fan in at 170F?
Okay for the summer but come winter, you may take a long time getting the engine up to operating temperature.

I know that the thermostat is supposed to regulate this but from my experience this winter with all the stat mods, the engine looses a lot of heat on its own. Kicking in a fan at 170F may only aid this loss.

I believe it is 170F air temperature, not coolant temperature. Coolant temperature should be higher.

Yup
Typically there is a 30F drop from the coolant temp to the outside of the thermostat. By the time the coolant gets into the radiator and dissipates the heat 170F air is quite hot. Remember that below the lock up, the fan clutch pretty much free wheels and does little if nothing. It is just when it is hot, that the Hayden fan clutch is more aggressive than stock. I notice little if no difference until it gets over 85F unless there is high humidity and them about 80F.
Saving my engine and making my AC run better is more important than worrying about theoretical hypothetical minute efficiencies that may or may not exist. That concern is for the Bean Counters who have the ISO 900X approved beans with etched serial numbers on them so they count them back into the jar in the correct order. :ROTFL:

Squeeto · **Posted:** Wed Jul 13, 2011 2:21 pm

Thanks guys.
Air vs coolant; obvious now that it has been pointed out to me.

I may require this fix so I need to know all the angles.

Also, does the 11 blade flex?
Could it be used for a fixed fan modification?

warp2diesel · **Posted:** Wed Jul 13, 2011 9:15 pm

Squeeto wrote:

Thanks guys.
Air vs coolant; obvious now that it has been pointed out to me.

I may require this fix so I need to know all the angles.

Also, does the 11 blade flex?
Could it be used for a fixed fan modification?

The 11 blade plastic fan is not sold as a flex fan.
It moves more Air and from what I understand it was originally a towing option fan for the '02 gassers. Gassers do put out more heat into the cooling system and exhaust than do diesels. That is one reason why our CRDs have the viscous heaters and some VW TDIs have glow plugs in the coolant line going to the heater core. Diesels tend to be more cold blooded than gassers.
Another advantage of the 11 blade fan is that it weighs less and has a slightly larger diameter.
The only negative thing I heard is that a guy from OZ who does a lot of river crossing speculated that it would flex when it hit water and go into the radiator. I suspect the river water being less than 170F would disengage the fan clutch and not create the problem.
Any one want to be a test subject? :pepper:

arengant · **Posted:** Fri Jul 22, 2011 12:05 am

I heard my fan go on first time (parked, idle with A/C on) and it wasn't as loud as I thought... Guess I will hold of on the Hayden fan

Fan Clutch

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