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Swapping electric fan for viscous fan and clutch
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=69189		 Page 1 of 1
Author:  Caddis [ Wed Jun 13, 2012 9:58 am ]
Post subject:  Swapping electric fan for viscous fan and clutch
I'm guessing this has been discussed on here before, but I haven't found any specific threads about it.
Has anyone tried swapping out the regular pulling/viscous engine fan and clutch for an electric unit, ideally with a separate thermostat so you could modify when it kicks in?
Author:  papaindigo [ Wed Jun 13, 2012 10:25 am ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
There has been discussion of this from time to time but I don't recall that anyone ever actually did the swap on a KJ. At least one of the issues was where to mount a temp sensor.

IMHO I'm not sure it's worth the bother. Some folks run ok with no fan (that's no fan just in front of the engine; the electric fan behind the grill is critcal to proper AC function) although that's not something I'd do personally. If you want constant extra cooling then Kap's fixed fan mod works fine although it's a bit noisey in town between 1500 and 2000 rpm but it does cool great and is unbreakable. Probably the best mod is the Hayden 2905 fan clutch which is much stronger than the factory fan clutch and engages at a radiator air temp IIRC of a bit over 170F which is just at the beginning of a temp rise instead of the IIRC ca. 200F engagement point of the factory clutch which is well after overheat has started as the radiator runs about 30F below block temp if the tstat is working correctly.

If you are looking for a small bit of hp and/or mpg savings the Hayden combined with the nylon gasser fan is a pretty light assembly that won't run with the clutch engaged much. An electric fan might be slightly better but...
Author:  fastRob [ Wed Jun 13, 2012 6:14 pm ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
Suggest you not do the electric.
Do a search, I think GMCTD demonstrated that the numbers are WAY different.
The old belt fan moves a huge amount of air, stock is sometimes pretty darn good.
Author:  warp2diesel [ Thu Jun 14, 2012 5:49 pm ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
fastRob wrote:
Suggest you not do the electric.
Do a search, I think GMCTD demonstrated that the numbers are WAY different.
The old belt fan moves a huge amount of air, stock is sometimes pretty darn good.


The electric fan choice or running with out a fan to get a small increase in fuel economy is not worth a cracked head or blown head gasket. Go with the Severe Duty Hayden instead of the Bean Counter Engineer bottom of the line OME crap viscous fan clutch. Many aftermarket suppliers show the choices and publish the specs, some are dropping the original OEM equivalent because it did not work very well and was not that much cheaper.
I have along with many others have the Hayden Severe Duty Viscous Fan Clutch and Nylon fan that exceeds the Bean Counter Engineer specifications originally chosen by Chrysler. As soon as I installed the AC worked much better than it worked before and it keeps the engine cool even in hot weather. Any claims of the steel fan moving more air (based upon the number of beans on the desk) than the nylon fan are highly suspect based upon what CRD owners have reported after they tried both with the Severe Duty Hayden clutch.
Author:  Drewd [ Sat Jun 23, 2012 9:30 pm ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
I lied, or as they say in the military, the truth changed. In previous posts, I stated that fan wasn't needed unless you were towing. Well, it got up to 100 deg F today and my engine coolant temp got up to 3/4 on the guage in stop/go traffic going mostly uphill with A/C running. It never did go over 3/4 on the guage but it did make me feel uncomfortable because it never has exceeded 1/2 guage in the past. I'm going to reinstall the OEM fan for peace of mind in the summer.
Author:  naturist [ Wed Jun 27, 2012 9:36 pm ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
@Drewd, if you are going to do that, spring for the Hayden. The OEM clutch is junk.
Author:  Joe Romas [ Thu Jun 28, 2012 7:25 am ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
naturist wrote:
@Drewd, if you are going to do that, spring for the Hayden. The OEM clutch is junk.


And while your at it add the 11 blade nylon fan too :JEEPIN:
Author:  Drewd [ Sun Jul 01, 2012 11:27 am ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
Drewd wrote:
I lied, or as they say in the military, the truth changed. In previous posts, I stated that fan wasn't needed unless you were towing. Well, it got up to 100 deg F today and my engine coolant temp got up to 3/4 on the guage in stop/go traffic going mostly uphill with A/C running. It never did go over 3/4 on the guage but it did make me feel uncomfortable because it never has exceeded 1/2 guage in the past. I'm going to reinstall the OEM fan for peace of mind in the summer.


Well, I've been too busy with work and other non-vehicle mechanical issues with stuff at the house to put the fan back on. Its been ok all week and here is what I've come up with: It appears to be ok running with no fan up to 95 deg F in most traffic conditions. In temps above 95 deg F in city driving, particularly stop and go going up hill, the vehicle temp will increase to 3/4 on the temp guage. While it is still a fair way below red, it made me uncomfortable.

I don't think I'll be able to re-install the new OEM fan anytime soon. My riding mower's transmission is %^&*(&^ed and my push mower just broke so I have to figure out a way to get my grass cut before my HOA starts screaming.
Author:  candpliberty [ Tue Jul 10, 2012 11:38 pm ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
I think mine is dead. I ran it til it was hot, parked, off, opened the hood and turned the fan with no effort. Bad clutch? It doesn't seem to be running hot but underhood temps seem very hot.
Author:  geordi [ Wed Jul 11, 2012 1:48 am ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
Is it the factory clutch?

Then it is dead. Plain and simple, they last about 100 miles, if that. The factory clutch is COMPLETE CRAP.

I am currently running with the Hayden, and I put back the metal blades for the moment b/c I haven't found the plastic at a boneyard for a price I like yet. What can I say, I'm being cheap b/c it is a freakin plastic fan, I don't think it is worth $80 at a dealer.

That said... I have the in-hose thermostat. Running WITHOUT a fan, even at 98+ degree temps (Ok, I didn't go anywhere on the days here when it was 101 with a feels-like of 116, I didn't even leave the house!!!) but my thermostat has basically been PAINTED ON at the dead-center position. With the exception of the big bridge on US-17 into Savannah, the land around here has a total elevation of about 2 feet above sea level. Hills? What are those? We do get some stop-and-go, and while the AC performance (without the fan) was obviously degraded... The engine temp never moved. WITH the metal blades and the Hayden, it does seem to be still fairly effective at the 97 degrees it was today. Once I get the plastic blades, I will report back about the AC performance with those. Hopefully it will be even better.
Author:  papaindigo [ Wed Jul 11, 2012 8:40 am ]
Post subject:  Re: Swapping electric fan for viscous fan and clutch
I've used Kap's fixed fan mod. Keeps things nice and cool but there is somewhat noticable fan noise between 1500 and 2000 rpm in town, nothing on highway. Just switched to Hayden clutch and 11 blade fan (ca. $60+tx via my friendly dealer parts manager) and it seems to be working fine.

If anyone wants the "hub" and washers needed to install a fixed fan drop me an email or PM as I've got those parts for cheap to a good home.

I can tell you that if you could spin the fan by hand with no effort on a hot engine the OEM clutch is virtually certainly dead. While I don't know how hot your engine was so I cannot comment on whether the clutch should be locked I can say with 100% certainty that spinning a fan on the OEM or Hayden clutch should not be "easy" as in just poke it and it rotates more or less freely. There is definite resistance.
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