How should the fan clutch feel?

APC9199 · **Posted:** Wed Jun 13, 2018 5:30 pm

I don't mean existentially or anything, I don't really care if it LIKES its job.

I was hauling a bunch of camping gear up a steep grade last weekend with no mechanical fan and the temp started to spike with the AC on. I backed off real quick and let it cool down, so no worries there, but this has all conjured up some confusion on my part. I reinstalled the old mechanical fan knowing that the clutch might not be any good. I was surprised when I went to turn it by hand and it was very stiff. It took about 50% of my strength to get it to turn the first time and even after being on and running awhile it is still very stiff. I noticed the "store this side down" text on the front when I took it out of storage, which is the OPPOSITE of how I had it stored. So I went and grabbed my other one from Jeep#2 which WAS stored proper side down and it felt the same way. So I install the first one and instantly notice the huge increase in sound with the fan installed. It is spinning pretty much all the time so I sound like a small plane taking off when I hit the accelerator. So I say screw it, I'll install the 11 blade fan and clutch from NAPA like so many here have done. I get the clutch from the guy at the counter and he starts ordering the fan which they didn't have in stock. I get the thing out of the box and low and behold, it feels EXACTLY like the other two I already have! That can't be coincidence, can it?! Shouldn't the clutch spin fairly free at room temp? Do I need to take it back and explain why it isn't right? What do you guys think?

WWDiesel · **Posted:** Wed Jun 13, 2018 9:45 pm

They have resistance even at room temperature. As the silicone fluid in the fan clutch heats up, the resistance becomes greater making the fan spin faster with less slippage in the clutch. At full lock, they are still only spinning at about 90% of engine speed according to Hayden's web site. :roll:

Hexus · **Posted:** Wed Jun 13, 2018 9:45 pm

No, if it spins freely it's shot.

rancherman · **Posted:** Wed Jun 13, 2018 11:39 pm

They are pretty stiff when it's zero out too.. takes several minutes for them to loosen up.

Seriously though, if you just grab the clutch part, and counter hold the hub, without a fan for leverage, they will seem pretty 'tight'. Even at room temp.

I'd say they are pretty noisy when first warming up, even on a 70 degree day. and when the temp gauge just starts to move off the peg, it should be pretty much be free wheeling (ok, a vast reduced rpm) soon afterward, right up to the point they re engage @ high temp.

CMSRock · **Joined:** Wed Mar 14, 2018 10:31 pm **Posts:** 12

I realize I am a month out on this but I just replaced my fan clutch on the 03 renegade. With the hood up I noticed the fan seemed to look slow, like really odd slow. This 03 kj has both the electric and viscous fan on it. I took a single sheet of paper rolled into a 1/2 inch diameter tube and could bring the fan blades to a stop pretty quick and spin it backwards with the engine at idle. Maybe not the safest test method but it works.

Got the new fan clutch from the FLAP and swapped them out. With both off the Jeep and cold I couldn't tell any difference. With the new one on at idle there was no comparison, visually faster and way stiffer on the paper tube test. Another thing to look at on these is to raise the hood and watch the fan at engine shutdown. The fan should stop in a a couple of seconds when you turn the engine off. A bad clutch should coast down for a while because the resistance is just not there. If yours works today with no issues watch it stop when you turn it off that way you will know what its supposed to look like and you will recognize the extra coasting when it goes bad.

Had the same issue with a 99 WJ a few years back except it would warm up about 20 degrees on the gage at idle and stop signs. Same tests, paper and coast time at shutdown. I checked my 06 crd and it was fine.

APC9199 · **Posted:** Wed Jul 18, 2018 10:01 pm

I appreciate the responses. I realize that I never acknowledged any of them! I guess my holdup was in thinking that a properly functioning clutch would be barely spinning at normal operating temps. I drove my CRD for almost a year with no mechanical fan at all and it blew my mind how loud it was putting one back on it, 5 blade OR 9 blade. I'm getting used to the extra noise and opted to stick with the 9 blade for now since it is a tiny bit quieter. I still get a bit of temp spike on the real steep climbs around here (8% grades) when it is 90+ outside and the AC is on. I end up having to turn the AC off and roll the windows down with the heat on to stay at-speed, or pull over for a minute and let it cool. I suspect the radiator needs to be cleaned since I've never done it and the carwash doesn't seem to get in there very well. I'll keep experimenting!

How should the fan clutch feel?

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