Zj fan clutch

Alright I did the swap on my 98 and I am not as happy as I thought. Sitting in traffic on these nice 95 degree days, the temp still climbs to the 215 area. No higher but I thought the Zj clutch would take care of that. It is no different than my stock fan clutch. Radiator is about 8 months old and the condensor is about 4 months old and they arnt clogged.

just my .02 but if it dosen't go any higher i wouldn't worrie about it that is really close to normal i run around that and sometimes higher
by the way is the AC on???
while it is on what about the e fan is it kicking on like it should???

Yes that is with ac and the e fan is on. I also checked to make sure I put the fan blade on right. Im not all that worried about it but I thought the advantage of the Zj clutch was better fan speed which meant lower temperatures. Actually I was told on here a while ago it would bring my temp below 210 and keep it there. That is where the confusion is.

Where did you buy the "ZJ" fan clutch? Some parts stores sell the standard fan clutch for XJ 4.0s and ZJ 4.0s.

Well I dont have any Napas close by so I went to a very large local store. Crossed the part number and the box says severe duty on it. The clutch part is much larger than what I had on there so I assumed I had the right thing.

When you start the motor first thing in the morning does it sound like a jet taking off under your hood?

When the ZJ HD fan clutch is engaged it makes NOISE and moves a lot of air. If you can't tell the difference, sounds like you got HOSED!

Yea I guess I did. It does not sound like a jet taking off. I also forgot to mention my tranny cooler is in front of the mechanical fan. I geuss I try to return this fan clutch and try to make it to Napa. I didnt go there first because its about a 40 min drive. Oh well

i put the napa fan clutch on and it seems to work pretty well. once you get used to the added noise, im sure youll be happy with it. ive been driving around in high 90s heat and the only time the temp goes to 210 is on the freeway going 75mph plus and upgrades. once i slow it down a bit and level off the temp comes back down quikly. even better is after running the jeep on the freeway for and hour and then suddenly back into stop and go traffic, the temps stay down. i figure my trans is the culprit for the high speed heating. i will replace the filter/screen and install a larger trans cooler, and possibly delete the trans lines to the radiator and let the larger external cooler be the primary. a trans temp guage will definatly be installed if i go that route. but all in all i do like the clutch fan and i believe it is helping. just dont like the noise, but ill get used to it im sure.

lol i have the hd fan clutch and when i first start in the morning it sounds like a jet engine

When you get to NAPA its the 97-98 ZJ HD fan clutch, part no. 272310, $44.

Don't let them sell you the ZJ MAX COOL, it won't fit.

Good luck.

Just a FYI ANY properly working fan clutch(of this type), when first started in the morning and reved up will sound like a really loud fan roar. This is b/c at that point the fan clutch is at its maximum speed per its pully RPM, b/c the viscous fluid inside it hasn't yet distributed evenly. Now remember here that its not like for the first minute or few minutes of driving it makes noise and then goes away. Once you start the car we are talking within 3-10 seconds is when the fan will be roaring. After that the fluid distributed itself, and it will be spinning the fan at the least fan speed per RPM of its pulley. So start the truck, wait a second or two to get some oil pressure, and then rev the engine to 2500 rpm or a bit higher and hold it there. You should hear the fan ROARING and then slowly fade out until you can then clearly hear what seems like just the engine running with no other noise. If the fan clutch does not roar after sitting over night and rev'd like mentioned about, it needs replacement/is defective/worn out ect. Also as a general rule, the colder it is outside when the engine is first started, the longer it will roar at full speed before it calms down. Thinking about it, it makes sense. The colder it is the less viscous the fluid is, and the longer it takes it to 'sling' itself outwards at which point the fans rpm drops...

I put the ZJ HD fan clutch in my Jeep 2 days ago because my old one was toast. I first didn't notice any noise difference when I started it, and thought "what the heck are they talking about it sounds like a jet engine?" I drove it the next day, and it is loud when driving as first gear winds out. It gets quieter after that, but it works awesome.

Just FYI, I have an aftermarket muffler, I think it's a Magnaflow IIRC, anyways, it's not super loud, and I barely notice the HD fan clutch over the exhaust. I wouldn't exactly say that it sounds like a jet taking off under the hood. That's a slight exaggeration. . . .

joshv98xj said:

Just FYI, I have an aftermarket muffler, I think it's a Magnaflow IIRC, anyways, it's not super loud, and I barely notice the HD fan clutch over the exhaust. I wouldn't exactly say that it sounds like a jet taking off under the hood. That's a slight exaggeration. . . .

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:gee: ya think?

Banditt007 said:

Just a FYI ANY properly working fan clutch(of this type), when first started in the morning and reved up will sound like a really loud fan roar.

Click to expand...

Agree, but the difference is a standard XJ fan clutch runs at 60-70 percent of shaft speed when engaged. The ZJ HD fan clutch runs at 80-90 percent of shaft speed.

Both the standard and ZJ HD fan clutches turn at 30 percent of shaft speed when disengaged.

And I'm not sure the cold has that much, if any, effect on the fluid--its silicone.

I have no 'facts' to back up my statement of the cold making the fan run loud longer, initially. However, I've noticed that the colder it gets outside, the longer it seems to roar before it shuts up. Just based on what i've noticed w/ my own jeep.

I didnt notice the louder fan. I just know it is not cooling like everyone says it should with this fan clutch

It only cools really well if everything else in your system is spot on. I swapped to the HD ZJ clutch from NAPA about two weeks ago. It does work exteremly better than stock, its loud as hell, and at @ 3500 RPMs people on side of the street look at you like your "disturbing" them, it is that loud. My cooling system is spot on, new waterpump, radiator cap (often neglected), thermostat, and spot on 50/50 fliud ratio. I also don't have an AC condenser up there. Mine will go up to around 210-215 in stop and go when the ambient temp is above 80. Most of the time it stays between the first mark and the 210.

You already stated that you didn't get the NAPA clutch, but thats not that big of a deal, a new clutch should perform pretty well.

If your coolong system is up to par, than you should be fine with that clutch. One thing that wasn't mentioned is that the Temp gauge in these things are not accurate by any means. Whats 210 on your gauge might be around 200 on anothers. Your rig sounds normal to me, as far as the fan goes.

How is the condition of the rest of your cooling system components? As I mentioned, one of the most neglected areas is the radiator cap. Don't guess, just replace it, ten bucks.

itbrokeagain said:

I didnt notice the louder fan. I just know it is not cooling like everyone says it should with this fan clutch

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I'd venture a guess that there's something else wrong with your Jeep then.

You said new rad, new fan clutch.

How's the t-stat? Did you flush the engine when you did the new rad?

Is your cat clogged? (check how hot your passenger floor gets after driving for a bit)

I will admit I did not flush. But the coolant is still a beautiful shade of green. Cant hurt to do it though.