mechanical fan clutch problems

My 92 Cherokee with 4.0 engine is overheating at idle and I've narrowed it down to the fan clutch. While driving at any speed the temperature stays normal. If I'm idleing in traffic for more than 3 or four minutes the temp creeps to the red zone on the gauge. I manually wired my electric fan to a switch and when I turn it on the temp drops back down to normal. My question is can anybody recommend where to get a good quality fan clutch. This is a new engine and I put on a new clutch from Quadratec but it leaked all of viscous fluid within the first two months. I now have a new Hayden fan clutch from Kragen and it still overheats in traffic. The fan clutch never locks up. Anybody know of a good quality fan clutch. Thanks

desertrandy said:

My 92 Cherokee with 4.0 engine is overheating at idle and I've narrowed it down to the fan clutch. While driving at any speed the temperature stays normal. If I'm idleing in traffic for more than 3 or four minutes the temp creeps to the red zone on the gauge. I manually wired my electric fan to a switch and when I turn it on the temp drops back down to normal. My question is can anybody recommend where to get a good quality fan clutch. This is a new engine and I put on a new clutch from Quadratec but it leaked all of viscous fluid within the first two months. I now have a new Hayden fan clutch from Kragen and it still overheats in traffic. The fan clutch never locks up. Anybody know of a good quality fan clutch. Thanks

Click to expand...

Hayden is good, are you sure you got the correct one?

Well, I can tell you which one NOT to get, and that's whatever brand C.A.P. (Consumer Auto Parts) stocks. Despite getting the thermostatic clutch, it's still locked up ALL the time. The only time there's any slippage is at WOT - it starts to slip around 4,500rpm...

I spent the extra money and went OEM from Newjeepparts.com So far works great no issues at all

The mechanical fan cluth IS a bit of a problem - although I've been getting 3-4 years' service out of Hayden units when I install them. I'm just getting tired of changing them - which is why I've desinged (and need to prototype) a fan clutch eliminator knuckle.

The low-end torque of the 242 is in SPADES, so losing a little to have the fan always running shouldn't be a problem. Also, I've depressed my operating temperature by about 20*F with no ill effects, so I'm fairly sure that value is a bit inflated (yet, I pass the California Air Nazis as well - as my temperature has gone down, so has my emissions. I'd pass without and EGR by an even wider margin if they'd just let me pull the damn thing...)

5-90

I sent you (5-90) an e-mail regarding your fan clutch eliminator. I am really interested in this product because i am moving to the mojave desert and could use the piece of mind knowing I have full air moving across my radiator. Also I drove a Ford pick-up for years with a solid fan hook up and am used to the quirks associated with it. Just let us know when they go into production and I'll definately buy one.

MrGasket makes them now.

langer1 said:

MrGasket makes them now.

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we need the rest of the info...part # etc....

give it up so I can give up my fan clutch.

I think I answered that already.

I've seen most "eliminators" out there - and they're either designed to take a flex fan (which flattens out at high crankshaft speeds and actually OPPOSES ram air flow!) or they're cast whatsits that just don't look well-designed.

I've got my design done, and I just need to get where I can start making them so I can prototype them. Mine will be CNC machined from wrought stock, and will use OEM hardware and fan blades - making installation easier. I also designed the knuckle to sit entirely behind the hub of the fan, so if your motor mount goes out, you shouldn't get that nice 8" round hole milled in your radiator by the fan clutch. There wasn't enough room to relocate the fan farther backwards comfortably, or I'd have done that as well.

Can't honestly say when I'll get this thing in prototype - I've got a few other things to get going first. And, does anyone nearby have a BA-10 they just got rid of (but still works) or an AX-15 with an input gear for NP231? My BA-10 sounds like I'm shaking a box of sledgehammers, and it's the third one that I've put in here!

5-90

One other possibility is the thermistor for the electric fan is out of range. They don't last forever and gradually go out of 'spec'.

I'd check the rest of the system as well. I took my clutch fan off this winter and haven't replaced it yet with an electric fan, although I have the new e-fan sitting here.

So far it has been 90* here and just the supplementary e-fan is keeping up without getting hot. Even in stop & slow traffic I haven't been hot. E-fan is going on this weekend for my Jeep.

desertrandy said:

If I'm idleing in traffic for more than 3 or four minutes the temp creeps to the red zone on the gauge. I manually wired my electric fan to a switch and when I turn it on the temp drops back down to normal.

Click to expand...

Does your electric fan switch on when you operate the AC? If it does, then you have a faulty coolant temp. sensor (the one in the t'stat housing). That's in addition to the bad viscous clutch that you have on the mechanical fan. If you can put up with a 15hp loss, you can do 5-90's clutch eliminator mod and have the fan locked up all the time.

Dr. Dyno said:

Does your electric fan switch on when you operate the AC? If it does, then you have a faulty coolant temp. sensor (the one in the t'stat housing). That's in addition to the bad viscous clutch that you have on the mechanical fan. If you can put up with a 15hp loss, you can do 5-90's clutch eliminator mod and have the fan locked up all the time.

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15HP? Just curious - where does that number come from? I don't have regular access to a dyno cell around here (at least, not for anything less than a King's ransom!) so once I get this thing going and proto'd, I don't think I'd be able to easily quantify the power drain.

However, it's also worth noting that the AMC242 lives at low RPM, where torque production is greater than horsepower. I don't suppose you could come up with a number for torque drain, could you? I've been wondering about that myself...

5-90

5-90 said:

15HP? Just curious - where does that number come from? I don't have regular access to a dyno cell around here (at least, not for anything less than a King's ransom!) so once I get this thing going and proto'd, I don't think I'd be able to easily quantify the power drain.

However, it's also worth noting that the AMC242 lives at low RPM, where torque production is greater than horsepower. I don't suppose you could come up with a number for torque drain, could you? I've been wondering about that myself...

5-90

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The figure was actually 12.5rwhp so accounting for drivetrain losses in a 4.0 ZJ, the flywheel figure would be 17hp. Here's the dyno graph:



....and the article that it came from:

http://www.mallcrawlin.com/forum/showthread.php?t=6355

Thanks!

You've certainly never given me reason to doubt your information - I just wanted to know the train of though, or (knowing you) the results you'd seen...

5-90

I remember when my dad took the fan clutch out of his old ford and ran a solid fan mount. There was noticeable drop in horsepower so a 15 horse loss sounds right and also you could definately tell there was no clutch because of the noise. However, the old ford had a 390 in it and that is also a torque monster so low end power was no problem. I just like the idea of max airflow at all times when wheeling in the desert. I have been know to hit Death Valley in July and August when the temps are in the high 120's. Also, it's not to hard to switch back to a fan clutch set up if needed. Everytime you do it, you learn a new shortcut and it gets easier to do.

This spacer/adapter replaces the fan clutch and hub by simply screwing onto the water pump. The fan bolts directly to the new spacer/adapter. The motion of the fan tightens spacer/adapter (may require additional spacing).

Part #
Thread Pitch
Thread Direction
851
30mm x 1.5
right hand-rev rot'n
852
30mm x 1.5
left hand-std. rot'n

langer1 said:

This spacer/adapter replaces the fan clutch and hub by simply screwing onto the water pump. The fan bolts directly to the new spacer/adapter. The motion of the fan tightens spacer/adapter (may require additional spacing).

Part #
Thread Pitch
Thread Direction
851
30mm x 1.5
right hand-rev rot'n
852
30mm x 1.5
left hand-std. rot'n

Click to expand...

Erm, isn't that a Ford/Chevvy part? I seem to recall that pretty much all XJ fan clutches are held on with the old-style "stud/nut" arrangement, rather than threaded onto the water pump hub. In fact, the mechanical fan doesn't even attach to the water pump in any particular wise - it's bolted to an idler hub just below the Air Conditioning most years, as I recall.

Granted, I could be wrong - but I'm fairly sure that that is at least, in part, mild spurion emissions... Not to say you're talking bollocks, I've run into a few catalogues that were wrong when we got them!

5-90