skidoo_j Posted May 9, 2012 Share Posted May 9, 2012 Okay so my fan clutch is bad. I've read in the FSM manual on how to test it. I have determined it's worth replacing. My question is what is the difference between the zj fan for the 97-98. Does it have a different temperature engagement or just a stronger clutch? I guess I'm trying to figure out how it's going to move more air if i'm using the same fan blades and the drive pulley is the same. I've read many people suggest it for use and to avoid the "extreme duty" but really what is the improvement from xj/mj vs zj fan clutch. Thanks in advance. Oh the test to determine if bad: Start truck. Block off air to radiator so it gets hot. Hold idle at 2400 rpm using a timing light.. when it gets to 190 degrees behind the radiator (they drill hole and insert a 8" long temp gauge i used a infrared gun) should take about 10 minutes and you should hear the fan engage and move more air. You can also use the timing light to note a difference in the rpm of the fan and there should be a significant difference. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 9, 2012 Share Posted May 9, 2012 Use the Napa # 272310 fan clutch for heavy duty use. Link to comment Share on other sites More sharing options...
skidoo_j Posted May 9, 2012 Author Share Posted May 9, 2012 Use the Napa # 272310 fan clutch for heavy duty use. but what is the difference or benefit? Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 9, 2012 Share Posted May 9, 2012 I tried the OEM ZJ clutch replacement and saw no appreciable difference while searching for a more effective way to cool the stroker while stuck in traffic on hot Bama days. There was no improvement in my case. The best solution for me, after many other attempts, was junking the mechanical fan altogether and fitting another electric fan (a 1997+ 10-blade version) with a separate controller with a manual override option if necessary. Did this back in 08, and it's worked fine ever since. http://www.comancheclub.com/forums/viewtopic.php?f=9&t=8342&hilit=electric+fan Link to comment Share on other sites More sharing options...
skidoo_j Posted May 9, 2012 Author Share Posted May 9, 2012 I tried the OEM ZJ clutch replacement and saw no appreciable difference while searching for a more effective way to cool the stroker while stuck in traffic on hot Bama days. There was no improvement in my case. The best solution for me, after many other attempts, was junking the mechanical fan altogether and fitting another electric fan (a 1997+ 10-blade version) with a separate controller with a manual override option if necessary. Did this back in 08, and it's worked fine ever since. http://www.comancheclub.com/forums/viewtopic.php?f=9&t=8342&hilit=electric+fan well i'm not having over heating issues, and am not running a modified engine. I think that just a functional fan clutch will be enough, but I had read multiple people saying to get this fan clutch from a zj and how it's better. But nobody has stated the why or how it's better even in other forums. Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 9, 2012 Share Posted May 9, 2012 Understand. Point was it was not "better" and there zero change in efficiency for me. Same-same. Link to comment Share on other sites More sharing options...
skidoo_j Posted May 9, 2012 Author Share Posted May 9, 2012 Understand. Point was it was not "better" and there zero change in efficiency for me. Same-same. Thanks. I took that away from your message :) before you put the zj fan clutch was your original working? I found this blurb on xj talk http://www.xjtalk.com/showthread.php?t=1587 "The HD Fan clutch is supposed to turn 70% to 90% of the shaft speed, as opposed to the 60% to 70% of the OEM XJ fan clutch. The one NEGATIVE thing I can say about this is that the clutch SCREAMS past 2800 rpm." So according to that statistic depending on the manufacture it could be equal to stock or upto 30% faster... I'm thinking I'm going to just get which ever they have instock at the parts counter. Link to comment Share on other sites More sharing options...
skidoo_j Posted May 9, 2012 Author Share Posted May 9, 2012 Now I've gone to napaonline.com and part 272310 doesnt list it fits a zj. Here's there fitment list for that part Jeep Cherokee 2.5 L 150 CID L4 AMC Design 1994 - 2000 Jeep TJ 4.0 L 242 CID L6 1997 - 1999 Jeep Wrangler 4.0 L 242 CID L6 1991 - 1995 Jeep Wrangler 4.0 L 242 CID L6 1997 - 1999 Jeep YJ 4.0 L 242 CID L6 1991 - 1995 They show different parts for the zj for 97-97 they show a 272306 for a v8 and 272314 for the i6 no max cool or non max cool. Link to comment Share on other sites More sharing options...
skidoo_j Posted May 9, 2012 Author Share Posted May 9, 2012 Now I've gone to napaonline.com and part 272310 doesnt list it fits a zj. Here's there fitment list for that part Jeep Cherokee 2.5 L 150 CID L4 AMC Design 1994 - 2000 Jeep TJ 4.0 L 242 CID L6 1997 - 1999 Jeep Wrangler 4.0 L 242 CID L6 1991 - 1995 Jeep Wrangler 4.0 L 242 CID L6 1997 - 1999 Jeep YJ 4.0 L 242 CID L6 1991 - 1995 They show different parts for the zj for 97-97 they show a 272306 for a v8 and 272314 for the i6 no max cool or non max cool. when comparing parts through autozone they do list the same fan clutch that fits the above and the 97 cherokee. And luckily my autozone has both in stock so i'm going to compare them side by side and decide. Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 9, 2012 Share Posted May 9, 2012 Here's the factory part numbers for the 94-96 model clutches. If memory serves me correctly I tried the 52027823. 94-96 ZJ w. V8, CLUTCH, Fan, Viscous Cooling 52028215, w/o Max. Cooling 52028214, w/Max Cooling 94-96 ZJ w. I6, CLUTCH, Fan, Viscous Cooling 52027824, w/o Max. Cooling 52027823, w/Max Cooling 94-96 XJ w. I6, CLUTCH, Fan, Viscous Cooling 52028327 Link to comment Share on other sites More sharing options...
skidoo_j Posted May 9, 2012 Author Share Posted May 9, 2012 Here's the factory part numbers for the 94-96 model clutches. If memory serves me correctly I tried the 52027823. 94-96 ZJ w. V8, CLUTCH, Fan, Viscous Cooling 52028215, w/o Max. Cooling 52028214, w/Max Cooling 94-96 ZJ w. I6, CLUTCH, Fan, Viscous Cooling 52027824, w/o Max. Cooling 52027823, w/Max Cooling 94-96 XJ w. I6, CLUTCH, Fan, Viscous Cooling 52028327 I'll be sure to not get that one then as you said it made no difference. Do you have the part numbers for the 97 98 Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 9, 2012 Share Posted May 9, 2012 Sorry, no. All I have is for the 97-99 XJ I6. 97-01 XJ w. I6, CLUTCH, Fan, Viscous Cooling 52079625 Link to comment Share on other sites More sharing options...
jeepcoma Posted May 9, 2012 Share Posted May 9, 2012 You don't want an HD clutch if you're using the stock fan. It will cool less effectively and wear out faster than the standard duty, for a stock application. "Heavy Duty" in the case of viscous clutches relates to the mass of the fan, the airflow, and the duty cycle. Go with HAYDEN Part # 2625. $35 from RockAuto. Testing procedures aside, you can usually tell by trying to spin the fan when the engine has been sitting overnight. Mine was frozen so bad it would slip on the belt rather than moving in the clutch. Link to comment Share on other sites More sharing options...
skidoo_j Posted May 10, 2012 Author Share Posted May 10, 2012 You don't want an HD clutch if you're using the stock fan. It will cool less effectively and wear out faster than the standard duty, for a stock application. "Heavy Duty" in the case of viscous clutches relates to the mass of the fan, the airflow, and the duty cycle. Go with HAYDEN Part # 2625. $35 from RockAuto. Testing procedures aside, you can usually tell by trying to spin the fan when the engine has been sitting overnight. Mine was frozen so bad it would slip on the belt rather than moving in the clutch. Day late and a dollar short. I picked one up already. I got the one from the zj. I sat them down on the counter and compared them as they had the oem replacement for the 89 and the one for the 97 grand. The only difference was the diameter of the clutch. The one for the zj looked better built. Are you sure it will end up less efficient, I don't care about longevity. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted May 10, 2012 Share Posted May 10, 2012 I have the ZJ fans on both my 4.0's. XJ and MJ. I noticed immediatly that the HD clutch moves more air than the stock XJ clutch (which was only about 2 weeks old on the MJ). It also took care of my cooling issues while towing or slow n' go. Some say it's much noiser, but I didn't really notice an "annoying" noise..more like "more power" sound. I am considering changing out the whole mechanical fan system on the MJ (XJ's been passed on to Sonny) but have to really work out all the electrical crap (like a new fuse box) before I do that. Having a constant and dependable source of air flow without extra drag on the engine sounds like a good plan. Link to comment Share on other sites More sharing options...
skidoo_j Posted May 11, 2012 Author Share Posted May 11, 2012 Alright I must have missed something... I pulled my fan clutch and fan off, removed the fan from the clutch and that's where I sit. The MJ fan blades will not fit on the ZJ fan clutch unless i flip it backwards... What am i doing wrong... I didnt read anywhere that people swapped the fan blades too. It's because of the increased diameter of the fan clutch. Am I the only one that's had this issue? The fan clutch i purchased was from autozone and is a torqueflo brand. The inside fins keep the mounting plate about an 1/8" off. The inside tips cannot be bent easily as there is a ridge mm's from where it would need to be bent. I don't want to remove any materials because it's balanced. So I'm taking it back to the store. Napa Doesn't have one in stock near me until monday, so I'm going to stop by schucks on the way to return/exchange and see if their hayden brand one is any different in manufacture then the torqueflo. Link to comment Share on other sites More sharing options...
skidoo_j Posted May 12, 2012 Author Share Posted May 12, 2012 I went to schucks and bought a Hayden fan and it worked perfectly. The torqueflo sold by autozone has fins that are made differently which prevent the fan blade from seating on the mounting surface. Oh side note when I told schucks 97 grand cherokee they only showed the max cool and said nothing else was listed in their system. Made no sense as I'd looked it up online to ensure they had it in-stock before I went there and that's how I looked it up, regardless I then told them to look up a '94 cherokee 2.5l and he brought me the clutch and I fit the fan on the counter. So apparently you can use one from Hayden or Napa, I suggest pulling your fan blade and taking it in with you when you purchase the fan clutch so you can ensure they don't change the mold or change to a different supplier and just rebox it as everything else seems to be anymore.. As far as others have posted about the fan moving closer to the radiator etc it is not of concern the difference is in thousandths of inches. I installed the Hayden fan clutch, (comes with new lock washer) I stopped at the hardware store and picked up new bolts to replace the studs 5/16 x 24 and new bolts into the fan clutch 5/16x18. I didn't have to loosen the radiator doing it this way. I then tested the fan clutch and it does move alot of air, but My comparison is to a non-working fan clutch. It's not all that loud, about as loud as when the electric fan turns on and runs. During the test of the fan clutch though I couldn't get it hot enough for the electric fan to turn on. That's with the radiator covered with carpet pad and a towel to prevent air flow. Again I have no comparison if a stock working fan clutch would do the same, but I"m happy to have a new fan clutch. And if this does cool better which it should as it's to lock up to a higher percentage of motor rpm, and faster spin should be more cfm. Link to comment Share on other sites More sharing options...
skidoo_j Posted August 11, 2012 Author Share Posted August 11, 2012 4-month review: Well the zj clutch fan definitely is loud. It seems to move a ton of air and the truck stays cool. I did end up having issues with a belt squeal about 3-4 weeks after original install. I think it was a combination of things. 1. Old belt 2. slightly worn fan pulley (excessive slope in belt running surface) 3. Bad fan bearing 4. added strain due to additional engagement of clutch. I ended up pulling off the whole clutch fan bracket and pressed out the bearing $12(it's a standard water pump bearing). It had a bit of play it in and thought it could have been causing the squeal. It was not hard to do the only pain was getting the mounting plate back on perfectly, I ended up either pulling it off the old or pressing it on the new bearing crooked so i had to spin the whole bearing on the lathe to make the mounting surface square to the bearing rotation. Since replacing the bearing I've ran the truck in stop and go traffic on 100 degree days and the aux fan has not turned on. Infact I began to think it wasn't working, so on one 100 degree day i covered the front of the truck with plastic and blankets, it took almost 10 minutes from cold before it turned on. I can say that the aux fan runs less on my comanche with this clutch installed vs my brother's cherokee with a regular fan clutch while driving caravan. We both have new radiators from radiator barn, new water pumps, and both running stock thermostats. The only other difference is I converted mine to an open system with an aluminum pressure tank from Mac's radiator. Link to comment Share on other sites More sharing options...
mvusse Posted August 11, 2012 Share Posted August 11, 2012 An open system does not have a pressure tank, it has a recovery or overflow tank. A closed system has a pressure tank. Link to comment Share on other sites More sharing options...
skidoo_j Posted August 11, 2012 Author Share Posted August 11, 2012 An open system does not have a pressure tank, it has a recovery or overflow tank. A closed system has a pressure tank. You would be incorrect. You can convert a closed system to an open system and retain the purge tank and stock radiator design. To convert to open on the cheap side is an inline filler with a pressure cap with a barb that will connect to an additional tank. I'm my case I opted for an alluminum tank and ran it to a factory 2.5 coolant bottle. viewtopic.php?f=2&t=32876&start=30 http://www.macsradiatorshop.com/surge-o ... tanks.html Link to comment Share on other sites More sharing options...
mvusse Posted August 15, 2012 Share Posted August 15, 2012 I ended up pulling off the whole clutch fan bracket and pressed out the bearing $12(it's a standard water pump bearing). Part number and source please. Need to replace mine tomorrow as it's going off road Friday. Link to comment Share on other sites More sharing options...
skidoo_j Posted August 15, 2012 Author Share Posted August 15, 2012 I ended up pulling off the whole clutch fan bracket and pressed out the bearing $12(it's a standard water pump bearing). Part number and source please. Need to replace mine tomorrow as it's going off road Friday. Sorry don't have a part number, I pressed mine out then took to a bearing supply store in my home town. Put it on the counter and he handed me one that I had to cut one shaft to length. I'll get you some exact measurements of the old one so you could call your local autoparts. I'm thinking the autoparts places that supply old school cars may have them on hand, like napa or carquest, maybe baxters. Link to comment Share on other sites More sharing options...
skidoo_j Posted August 16, 2012 Author Share Posted August 16, 2012 Shaft Diameter : .6267" Bearing Diameter: 1.1811" Total Length: 4.56" Short Side (fan side): 1.10" Long Side (goes up inside bracket not all to important on this length): 1.930" Looks like napa BRG 885154B would work, it wouldnt have the shaft that goes back inside the bracket, but if you can't source it else where, It looks like it would still need a bit of shortening. but 12 dollars beat 120 for the bracket with the bearing (that's the only way my dealership would sell me). Good luck. Link to comment Share on other sites More sharing options...
mvusse Posted August 16, 2012 Share Posted August 16, 2012 Many thanks. According to their web site TSC might possible also have some that may work, also without the back side of the shaft. Link to comment Share on other sites More sharing options...
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