JPHunter91

Recently installed the ZJ fan clutch in my 98' XJ and boy was it worth it! Swapped over to dual electric fans about 6 months ago and a few weeks ago I decided to go back to stock. I have had the ZJ clutch in for almost a week. Here are some things I've noticed so far.

PRO's: Cooler engine temp, cooler A/C, cooler engine temps, and did I mention cooler engine temps? No more overheating!

CON's: Slightly more noise but after a few days I don't notice it anymore, slightly worse MPG- (about 1/2 MPG)

Read a few peoples comments on here about the swap and they said there was a noticeable loss of power, personally I have yet to notice any between the XJ clutch and the ZJ clutch. However I did notice a deference between having dual electric fans and having the mech fan in there.

Mileage with the dual e fans was usually around 17.5 MPG, but the jeep still ran too hot for my liking- about 210 on the highway and 220 in town.
With the stock fan clutch I was getting on average 16.5 MPG, engine temps were usually at 210 all the time unless I was stuck in traffic or towing a trailer it would creep up to 220

With the ZJ fan clutch installed I've only gone thru 3 tanks of gas but so far the average is 16.1 MPG, Here's the good part... I haven't seen 190 on the temp gauge yet, at all, and that's including towing a 16ft trailer with a small car on it and sitting in traffic in 105* heat. Another pleasant side effect of the ZJ swap is my A/C is about 5* cooler (71*-66*)

All in all I'd definitely recommend anyone with cooling issues as long as you aren't worried about a little noise and a slight drop in mileage

Cheep Jerokee

Would you please tell me what the brand and part number ZJ fan clutch you used is???


I did a lot of searching for this info and could not find a ZJ fan clutch that would fit my 96 XJ. Lots of mentions to doing this so called upgrade but no data to go along with the name. Finally found one reference to a brand and part number only to discover that it was an HD for the XJ only, no connection to the ZJ.

JPHunter91

I just went to autozone and asked for a 98 ZJ 4.0 fan clutch. I believe it's this one
http://m.autozone.com/autozone-mobil...pd92?id=265348

Should fit on your 96', I made the mistake of tossing the mech fan when I switched to dual electric so I pulled one from a buddy's 96' parts jeep and installed the new clutch on it.

JPHunter91

Just make sure it's the ZJ clutch WITHOUT HD cooling and it should work

EZEARL

The HD fan clutch your referring to is NAPA #272310? It's definitely an upgrade over the oem one.

Cheep Jerokee

Yes, it is an upgrade over the standard clutch and is what I am currently running. But that Napa part number has no connection to the ZJ. Napa only lists it for the XJ. I'm looking to find out what exactly the brand, part number and ZJ application is for the fabled ZJ conversion fan clutch that is supposed to work so well (and maybe hopefully better than what I have now), that's all...

PocketsEmpty

I still had my 31's on when I first put the ZJ fan clutch in. It helped a good bit, and I have a trans cooler in front of it now and it's hard for my trans to get above 160 degrees. I definitely noticed a slight loss of power. But now I have 33s and really want to regear...so I will probably leave it on there. My engine temps still hang around 195 ish when I have the electric fan on as well.

cruiser54

It's been the 272310 forever.

Napa's catalog is incorrect then.

cruiser54

What thermostat do you have in there?

CobraMarty

XJ Upgraded HD Fan Clutch-
Hayden #2737 Amazon $41 free ship have used on 3 different Jeeps, works well
NAPA #272310 $43 quoted by many user, no personal experience, ?loud

EZEARL

^ that. The "ZJ upgrade" is the HD clutch used on the 2.5's.

http://www.napaonline.com/Catalog/Re...8004%205999999

PocketsEmpty

A 195

jeepkid03

I tried the ZJ fan clutch for one summer and hated it. The noise wasn't too annoying except for when merging on the highway, the thing still didn't unlock even when revved up to 3,000 RPM. Any higher and I could probably suck birds in through the radiator.

The fan definitely pulls a lot of air, my problem was it pulls too much and didn't fix the problem. I still had temp spikes, and with the ZJ fan they were even more drastic. Before my Jeep would occasionally go to 215-220, but it mostly stayed at 210-212. With the ZJ fan, I could pull out onto a road and the fan would be 100% engaged, which would make the temp spike from 212 or whatever all the way down to 180*. Then on the highway it would creep back up to 215. The temp would swing back and forth, and in the winter it ran at 180* constantly. My buddy had similar results when we used one in his XJ.

My solution was to go back to the factory cooling system, but make it better.

I have a CSF 3 row radiator, and a Stant Super Stat 195* thermostat. I replaced the water pump with a new Mopar one even though the old one looked okay when I pulled it out. I replaced all the hoses and installed a new radiator cap along with a coolant flush. I used a new stock sized fan clutch from Autozone.

I'm going on 3 years with this setup, and I couldn't be happier. My temp stays steady, and the highest it has gotten has been 211* according to my scan gauge II. That was on a 95* humid day pulling a trailer up a hill. A few seconds later the temp went back down to 200*. My summer running temps are 200-206* and winter temps are 195-200*. I lost 1-2 mpg with the ZJ fan, and now I've been getting 17.5mpg, which I think is pretty good for a Jeep with a 2" lift and 30s.

Kerry6363

What are the physical differences between the ZJ and XJ fan clutch?

cruiser54

Not much. Why?