Should you get a heavy duty fan clutch?

freedom_in_4low said:
I wish there was a water pump with the four bolt flange for the newer motors, haha. I don't know of one single thing that was wrong with that setup, other than that it probably took the factory 4x as long to assemble it.
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I used to say that, but honestly the 4-bolt is a pain in my mind. People complain about the thread on style getting “stuck” but honestly I haven’t seen one that doesn’t come apart by using a crescent wrench, setting it on the large nut vertically, hammering on the end of the crescent and tugging lightly in the unthread direction. Assuming you have no troubles beyond doing that, it’s much faster to use the thread on clutches.

The main reason the 4 bolts and nuts sucks to me is because it’s just hard to get the wrench on there and even when you get all the nuts off, the clutch wants to stay on the water pump until you wiggle it, then it comes loose and you slam the fan into the radiator. At least that’s how it always seems to go in my experience. Maybe I’m just not careful enough though.
 
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machoheadgames said:
I used to say that, but honestly the 4-bolt is a pain in my mind. People complain about the thread on style getting “stuck” but honestly I haven’t seen one that doesn’t come apart by using a crescent wrench, setting it on the large nut vertically, hammering on the end of the crescent and tugging lightly in the unthread direction. Assuming you have no troubles beyond doing that, it’s much faster to use the thread on clutches.

The main reason the 4 bolts and nuts sucks to me is because it’s just hard to get the wrench on there and even when you get all the nuts off, the clutch wants to stay on the water pump until you wiggle it, then it comes loose and you slam the fan into the radiator. At least that’s how it always seems to go in my experience. Maybe I’m just not careful enough though.
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^^^THIS^^^

The old MBZ has the 4 bolt style, and its a minor bitch to deal with. OTOH, hammering on the end of the wrench has never worked for me so I have to bolt a tool onto the pulley - BUT - that's one HELL of a lot easier and faster than dealing with a 4 bolt clutch/fan lashup. YMMV and all that...
 
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Mopar 68064765AA clutch came in and looks exactly like the 2791 fan clutch. So props to @pagrey for pointing this out. Same patent numbers fwiw, same rotation.

Of course what matters is in the insides and I can't confirm that. Perhaps they have slightly different oil or clutch setup but I would bet they are the same or very similar.

Mopar was about $134
Hayden is about $42

I have not installed the Mopar unit yet. I am half tempted to send it back lol since the Hayden 2791 seemed to keep my temps in check.

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Back of Mopar unit

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Back of the Hayden 2791

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Longwhitejeep said:
Same patent numbers fwiw, same rotation.
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It's impressive to me how similar they are yet still different enough that they didn't come out of the same mold (the lettering and markings have a different appearance).

In case anyone finds it interesting, here's some info on the patent.
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Abstract​



A viscous fluid clutch assembly used in automobiles, SUVs, and trucks minimizes flow back of the cooling fluid from the reservoir towards the working chamber of the clutch when the vehicle is at rest and avoids excessive fan noise, wasted power and fuel inefficiency when a cold automobile engine is started. The clutch utilizes a discharge channel extending from the periphery of the working chamber to the reservoir and a specially designed ball check valve at the entrance to the reservoir which is open or closed depending on operation of the vehicle. The ball check valve is fluidly connected to the working chamber of the fluid clutch by a preferred articulated discharge channel which starts at the working chamber of the fluid clutch and ends at the reservoir of the fluid clutch.
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TexasTJ2004 said:
I have installed the 2771 Hayden today. It does not seem like it makes any difference compared to OEM.
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Compared to the 2971 extreme duty which this thread is about, internally the 2771 has about 40% of what Hayden calls the working area compared to a stock clutch Mopar clutch. It's essentially just a lighter duty clutch. It'll be fine. It will probably wear out sooner. At least that's what Hayden says. "Cooler running and longer life" referring to the extreme duty clutch itself. Next time given the option you should look into sourcing the 2971. The 2771 is different, most people wont be able to tell how different they are, you obviously fit that description. I wouldn't worry about it, some details aren't worth digging into. There is nothing wrong with just replacing the part and moving on.
 
pagrey said:
Compared to the 2971 extreme duty which this thread is about, internally the 2771 has about 40% of what Hayden calls the working area compared to a stock clutch Mopar clutch. It's essentially just a lighter duty clutch. It'll be fine. It will probably wear out sooner. At least that's what Hayden says. "Cooler running and longer life" referring to the extreme duty clutch itself. Next time given the option you should look into sourcing the 2971. The 2771 is different, most people wont be able to tell how different they are, you obviously fit that description. I wouldn't worry about it, some details aren't worth digging into. There is nothing wrong with just replacing the part and moving on.
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Based on Chris, Jerry and other folks opinion here, it seems like good flush, and then installing hayden 2771 + Mopar Thermostat + Mopar Radiator, assuming waterpump (it is a a simple mechanical piece, that I dont really expect to go wrong, unless maybe leaking from the bearing and seal) in a good shape will get us to cool Nirvana of never worrying about potential overheat:).
 
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Interesting observations today. Temp was mid 90's outside, A/C on max the whole day. Ran some errands in town, then headed out to some of the dirt/sand roads out in the country near my house. Hayden 2791 fan clutch installed. Around town and stop and go traffic temps fluctuate between 203* -210* on the Dash Command App. Seemed pretty normal. Once done with my errands, I headed out to the dirt roads. Slow driving between 5 - 15 MPH, stopping every now and then to watch snakes and deer. While sitting still, temps creeped up to 217*-223* and quickly dropped down to low 200's after moving again. Spent about 1-1/2 hours out doing this.

Went to a restaurant to get something to eat. About 10 cars ahead of me so I spent about 15 minutes in line. A/C still on max, temp on Dash Command App got up to 239*. After getting my food and heading back home, temps dropped again to low 200's while driving in the 2 miles back to my house.

Decided to put the 2771 back on and see what it did. Swapped them out, let the jeep sit and idle for 30 minutes. It ran for 20 minutes before it reached 225* and by 30 minutes it was 237*. Again, temps dropped to low 220's pretty soon after driving. When the Dash Command App showed 239* with the 2791 clutch and 237 with the 2771, the temp gauge on the dash showed about the same, just starting to get into the zero of the 210 lettering. I've seen the instrument cluster gauge get up into that range before with the 2771 was on but never realized it was high 230's because I've never used the Dash Command App when sitting and idling for that long, I guess.

@freedom_in_4low , @Longwhitejeep and @pagrey , I'd be interested in hearing what temps you show if you have an OBDII reader that shows temps when sitting idling for 20 - 30 minutes.

Dash Command App screenshot and pic of the instrument cluster with the 2791 clutch installed.
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MountaineerTom said:
Interesting observations today. Temp was mid 90's outside, A/C on max the whole day. Ran some errands in town, then headed out to some of the dirt/sand roads out in the country near my house. Hayden 2791 fan clutch installed. Around town and stop and go traffic temps fluctuate between 203* -210* on the Dash Command App. Seemed pretty normal. Once done with my errands, I headed out to the dirt roads. Slow driving between 5 - 15 MPH, stopping every now and then to watch snakes and deer. Whie sitting still, temps creeped up to 217*-223* and quickly dropped down to low 200's after moving again. Spent about 1-1/2 hours out doing this.

Went to a restaurant to get some \thing to eat. About 10 cars ahead of me so I spent about 15 minutes in line. A/C still on max, temp on Dash Command App got up to 239*. After getting my food and heading back home, temps dropped again to low 200's while driving in the 2 miles back to my house.

Decided to put the 2771 back on and see what it did. Swapped them out, let the jeep sit and idle for 30 minutes. It ran for 20 minutes before it reached 225* and by 30 minutes it was 237*. Again, temps dropped to low 220's pretty soon after driving. When the Dash Command App showed 239* with the 2791 clutch and 237 with the 2771, the temp gauge on the dash showed about the same, just starting to get into the zero of the 210 lettering. I've seen the instrument cluster gauge get up into that range before when the 2771 was on but never realized it was high 230's because I've never used the Dash Command App when sitting and idling for that long, I guess.

@freedom_in_4low , @Longwhitejeep and @pagrey , I'd be interested in hearing what temps you show if you have an OBDII reader that shows temps when sitting idling for 20 - 30 minutes.

Dash Command App screenshot and pic of the instrument cluster with the 2791 clutch installed.
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I saw some similar results. But didn't get quite above 230 but came close. I checked my radiator temps with a temp gun and they were a little under what my torque App was reading off the obd2 by a few degrees.

I think maybe it's the humidity we see on this side of the country. My temps and the weather that day. Sometimes the App would register a spike to 230 but that was after shutting the jeep off. So those temps are going to climb a few degrees when you shut it down.

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I do have a bunch of coolant overhaul items showing up this week due to a small radiator leak at the tank seam I discovered when testing this clutch.

I am going to do some more testing with my current setup to get a baseline for any improvements. Though I do think th 2791 clutch solved my issues as stock clutch allowed the temps to get higher at idle in the driveway.

Stock clutch temps same day allowed tempsm to creep up to 238 at idle with ac on. I shut it off at thise temps. It did past the cardboard to fan blade test many always mention as a sign of a bad fan clutch. If it stops spinning. My stock one kept spinning but didn't cool as well as the 2791
 
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Longwhitejeep said:
I saw some similar results. But didn't get quite above 230 but came close. I checked my radiator temps with a temp gun and they were a little under what my torque App was reading off the obd2 by a few degrees.

I think maybe it's the humidity we see on this side of the country. My temps and the weather that day. Sometimes the App would register a spike to 230 but that was after shutting the jeep off. So those temps are going to climb a few degrees when you shut it down.

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The humidity was about the same here yesterday. It's already 70% here today.

Like I mentioned before, I've seen the OEM gauge show that before, but never had the OBD2 reader hooked up at the same time. I was surprised to that that reading equated to upper 230's.

I did notice while creeping around on the dirt roads yesterday with the 2791 clutch that the A/C was 3 to 4 degrees cooler that what it normally is. I was using one of those dial thermometers that stick in the A/C vents. Not a whole lot of change.
 
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The humidity shouldn't have any impact with AC off, but it absolutely makes a difference with it on. All that water that condenses on the evaporator is heat added to the refrigerant and has to be rejected at the condenser, raising the temperature of the air coming off the condenser and hitting your radiator. In the industry we call that "latent heat" because it's energy that isn't accounted for by the temperature change of the air (which is called sensible heat because you can sense it).
 
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MountaineerTom said:
The humidity was about the same here yesterday. It's already 70% here today.

Like I mentioned before, I've seen the OEM gauge show that before, but never had the OBD2 reader hooked up at the same time. I was surprised to that that reading equated to upper 230's.

I did notice while creeping around on the dirt roads yesterday with the 2791 clutch that the A/C was 3 to 4 degrees cooler that what it normally is. I was using one of those dial thermometers that stick in the A/C vents. Not a whole lot of change.
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Yeah same here with the temps. It can be deceiving when you read folks who post online about their temps never reaching above 210. Then you see things like this on your own jeep and makes you question your life decisions. It did for me 😆. I thought I was all good with the cooling until I noticed the seam leak. My radiator still has the factory paint marks on the clamps.


I was home free with the Hayden then my jeep said f you man and sprung a leak.
 
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This is what I'm seeing today with my setup. Good news I don't have a radiator leak. It was the upper hose lose which was been corrected. Still monitoring this though. I am not losing coolant, at least not enough to notice yet. Belt squeals on command at and above 3k in 1st and 2nd gear. I'm going to try a new belt. I'll save the new radiator I purchased for now. I don't mud this jeep but I'll give the radiator a cleaning too. System was flushed last year with new heater hoses.

It is 100 here today and I got to 240 after a drive a up to Ace for an errand. It hit 240 in the parking lot after about 10 minutes of sitting once I arrived with the ac on max. All with the 2791 installed.

This what that looks like on my gauge at 242. It's hot today

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sitting in the jeep typing this and it's back up.to 242 degrees. I'm going to clean this radiator for now and see what does.

There is very mixed info it seems on the acceptable temp range for these. Some day 210 to 240 is normal. Some say above 230 is not normal. I'm over it for now and

Especially if @MountaineerTom is seeing similar results from a refreshed system. Meanwhile @rasband sitting nice with a very fresh system.
 
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