Just curious why the ZJ clutch is "better".

Pulls more air, ever heard a 757 at take off? Lol

When the air coming through the radiator is hot enough to "engage" the clutch fan, the stock one goes 40% of driven speed whereas the ZJ one goes 60% of driven speed.

Im actually running a 2.5 4cyl fan clutch on mine. More clearence for csf three core . And still pulls better than stock xj did.

Is the ZJ fan clutch you are supposed to get part #272314? That's all I'm seeing but the other threads on naxja and whatnot say it's supposed to be 272310

NO! 272310 is the one you want for an XJ.

10-4. Thank you

As I mentioned in an earlier post, I have the Napa 272310 fan clutch and now also a CSF 3 row radiator. It does make a far amount of noise but not that bad. It does seem to work well in Southern Arizona heat as long as traffic stops are short and otherwise going at least 25 mph and 2000 rpm. Any speed slower than that and the temp starts climbing even with going to as low of trans and transfer gear as possible to keep the rpm up. As long as the ambient temps are 85 or less, coolant temp will stay below 215. Any higher ambient temps and I have to keep the speed up, turn the a/c off and turn the aux fan on, or park the jeep and shut it off until it cools off, or D all of the above. If this is supposed to be the best there is, I am quite disappointed in my first and possibly my last Jeep vehicle. I am now looking at converting to all electric radiator fans with the hope of controlling this temp problem. :wallbash:

I'm in Yuma and with the stock fan clutch and the electric fan on I can keep my temp at 190℉ pretty much all day. Even in the 115℉ heat it has no problem staying cool. I have the stock single core radiator, old style e fan, and hood vents.

Well, I guess my Jeep is a POS lemon... :dunno:

have you replaced your water pump and thermostat? Mine had that same issue when I got it a few years ago and replacing those parts helped.

I use all the above and have no cooling problems.

For you guys in AZ and the higher temps-
I also use 2 10" pusher fans in front of the radiator. These really help when off roading and crawling and sitting in traffic. Can wire to a switch of thermostatic switch. They work great to help get air flow across the radiator.

There is something wrong with your cooling system. You should track down what that is - the beefier fan clutch is likely only a bandaid for your problems. Search the forums there are many good posts about how to troubleshoot your cooling system.

To the OP, I looked into whether or not to swap in the ZJ fan clutch on my XJ pretty extensively earlier this year and I ultimately concluded (based on other's feedback) the following

I live in Virginia and we had one of the coldest winters in a long time last year (consistent days where temps did not rise above freezing). In the summer I am sure the ZJ fan clutch would be great (although my cooling system operates fine, and now I have wired a switch to my aux fan for those really hot days where I need a little extra cooling I can switch the fan on manually), but I know it would have kept my Jeep too cool in the winter, which is why I am just replacing my fan clutch with an OEM part (whenever I decide to get off my a$$ and install it).

A better mod may be adding an override switch to the aux fan. I have found this to work perfectly for me on those 95* plus days in the summer when the AC is pumping. Most of the time I don't need the extra air circulation, but it's nice to have. Whereas the ZJ fan clutch you don't have control over it, it's always operating.

I haven't heard of that but it makes sense, I live in kansas and it can get kinda cold here in the winter. I'll keep that in mind and might switch back to a xj clutch if need be. Thanks for the heads up

UPDATE. It got into the 30's today and the ZJ fan clutch mod kept the temps about half way between the 100 and 210 marks while on the highway. My heater also seems weaker on the highway as well, not sure if that is because of the fan clutch keeping the temps down or my heater core is clogged. I will be switching back to a XJ clutch for the winter.