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Fan clutch
https://slantsix.org/forum/viewtopic.php?t=29997		 Page 1 of 2
Author:  Jopapa [ Mon Jul 14, 2008 10:45 am ]
Post subject:  Fan clutch
In an effort to gain a little economy while I'm driving my Duster (once I get it back on the road) I want to swap out my fan for a clutch fan. But I'm wondering if anyone here has a pic of a clutch fan installed so I can tell how to orient the clutch? I'm sure once I have the part in hand it'll be easy to tell (all I have to go off of is pics of the clutch itself on the retail sites), but sometimes I'm just not that smart.
Author:  Joshie225 [ Mon Jul 14, 2008 10:52 am ]
Post subject: 
The fan clutch is impossible to install backwards. The fan blade can be installed backwards. The fan should be offset toward the engine rather than the radiator.
Author:  Jopapa [ Mon Jul 14, 2008 10:57 am ]
Post subject: 
Quote:
The fan clutch is impossible to install backwards. The fan blade can be installed backwards. The fan should be offset toward the engine rather than the radiator.
Oh cool. That makes it easy for an idiot like me to keep from screwing it up :oops:
Author:  SlantSixDan [ Mon Jul 14, 2008 11:20 am ]
Post subject: 
The clutch can be installed only one way: The clutch's hub bolts to the water pump pulley, and the fan blade bolts to the rear face of the clutch body itself. The fan blade used with the clutch has a large centre hole (rather than 4 bolt holes and a centre pilot hole). This is so that you can put the fan clutch hub through the fan blade's central hole, bolt the fan blade to the clutch body, then bolt the fan clutch hub to the water pump pulley.

It can be a real challenge finding a fan clutch that fits in the short space available in an A-body slant-6 application, and works the way you want it to. There are many different fan clutches; they are not all alike. Cooling and noise characteristics and the power and economy gains are dependent on the type you install. The simplest fan clutches are centrifugal. They drive the fan below a certain RPM, and let it freewheel above a certain RPM. The better fan clutches are thermostatic. They have a coiled bimetallic spring on the front, which reacts to the temperature of air at the front of the fan to open or close a control valve in the clutch, engaging or disengaging it. But even these are not all the same. There are light-duty and heavy-duty fan clutches, and within those categories they differ in such things as temperature setpoint and presence/absence of an idle-lock feature. The idle-lock feature, which is usually found only in heavy-duty clutches, is essentially the addition of the centrifugal clutch function to the thermostatic clutch: it engages the clutch to drive the fan whenever the engine is at idle or low speed. Without the idle-lock feature, the clutch is purely thermostatic. If the air temp coming off the radiator isn't high enough to make the clutch engage, the fan will not be driven. In situations calling for assured airflow at idle and low speed (presence of A/C, lots of low-speed/stuck-in-traffic driving), you want a clutch with idle-lock.

The MP "performance" fan and clutch package is a production light-duty
5-blade fan and a light-duty clutch without idle-lock. It's a pair of those many standard parts that were pulled right off of production and given "P" part numbers and a blurb in the MP catalog talking up the (nonexistent) special performance nature of the parts. If the demands on your cooling system are ordinary, this package would do fine. However, if for whatever reason you want or need more airflow across the radiator and A/C condenser, you can do well with a wrecking yard fan (7 blade in your choice of pitch and diameter) and a Chrysler p/n 4266 665 clutch (heavy duty with idle-lock). When shopping the yards for fan blades, look under the hood of whatever RWD American car or truck you happen across; the bolt pattern of the fan blade to the clutch is pretty universal though the industry, and as long as the vehicle you're looking at uses V-belts and not a serpentine belt (which usually means a reverse-rotation fan and clutch), you're all set. Dodge trucks through '93 are good candidates.
Author:  Jopapa [ Mon Jul 14, 2008 1:55 pm ]
Post subject: 
Quote:
The clutch can be installed only one way: The clutch's hub bolts to the water pump pulley, and the fan blade bolts to the rear face of the clutch body itself. The fan blade used with the clutch has a large centre hole (rather than 4 bolt holes and a centre pilot hole). This is so that you can put the fan clutch hub through the fan blade's central hole, bolt the fan blade to the clutch body, then bolt the fan clutch hub to the water pump pulley.

It can be a real challenge finding a fan clutch that fits in the short space available in an A-body slant-6 application, and works the way you want it to. There are many different fan clutches; they are not all alike. Cooling and noise characteristics and the power and economy gains are dependent on the type you install. The simplest fan clutches are centrifugal. They drive the fan below a certain RPM, and let it freewheel above a certain RPM. The better fan clutches are thermostatic. They have a coiled bimetallic spring on the front, which reacts to the temperature of air at the front of the fan to open or close a control valve in the clutch, engaging or disengaging it. But even these are not all the same. There are light-duty and heavy-duty fan clutches, and within those categories they differ in such things as temperature setpoint and presence/absence of an idle-lock feature. The idle-lock feature, which is usually found only in heavy-duty clutches, is essentially the addition of the centrifugal clutch function to the thermostatic clutch: it engages the clutch to drive the fan whenever the engine is at idle or low speed. Without the idle-lock feature, the clutch is purely thermostatic. If the air temp coming off the radiator isn't high enough to make the clutch engage, the fan will not be driven. In situations calling for assured airflow at idle and low speed (presence of A/C, lots of low-speed/stuck-in-traffic driving), you want a clutch with idle-lock.

The MP "performance" fan and clutch package is a production light-duty
5-blade fan and a light-duty clutch without idle-lock. It's a pair of those many standard parts that were pulled right off of production and given "P" part numbers and a blurb in the MP catalog talking up the (nonexistent) special performance nature of the parts. If the demands on your cooling system are ordinary, this package would do fine. However, if for whatever reason you want or need more airflow across the radiator and A/C condenser, you can do well with a wrecking yard fan (7 blade in your choice of pitch and diameter) and a Chrysler p/n 4266 665 clutch (heavy duty with idle-lock). When shopping the yards for fan blades, look under the hood of whatever RWD American car or truck you happen across; the bolt pattern of the fan blade to the clutch is pretty universal though the industry, and as long as the vehicle you're looking at uses V-belts and not a serpentine belt (which usually means a reverse-rotation fan and clutch), you're all set. Dodge trucks through '93 are good candidates.
Yeah it's just a basic setup (just want the clutch fan to last me until I have the alternator upgraded and can take the time and money to figure out the type of electric fan setup I want) with no A/C and no extra cooling performance needed.

Is it recommended to use a shroud with a clutch driven fan, or am I good without it (I don't have one at this point).
Author:  SlantSixDan [ Mon Jul 14, 2008 2:40 pm ]
Post subject: 
Shroud vs. no-shroud is not dependent on clutch vs. no-clutch.
Author:  Jopapa [ Mon Jul 14, 2008 2:48 pm ]
Post subject: 
Quote:
Shroud vs. no-shroud is not dependent on clutch vs. no-clutch.
So regardless of whether I have a clutch fan or not, would you recommend a shroud?
Author:  SlantSixDan [ Mon Jul 14, 2008 3:08 pm ]
Post subject: 
Yup, fan shrouds are good. They help with cooling at low vehicle speeds.
Author:  Jopapa [ Mon Jul 14, 2008 3:20 pm ]
Post subject: 
Quote:
Yup, fan shrouds are good. They help with cooling at low vehicle speeds.
Reason enough for me. Any suggestions on where to track one down for a 22" rad? I'm going to go ahead with the MP clutch fan kit too, once my paychecks get unSNAFU'd.
Author:  SlantSixDan [ Mon Jul 14, 2008 3:28 pm ]
Post subject: 
Start posting "parts wanted" ads; this shroud isn't available new. Note that you need a Slant-6 shroud; the V8 item won't work (fan circle centred rather than offset).
Author:  DusterIdiot [ Mon Jul 14, 2008 6:27 pm ]
Post subject:  The parts exchange...
I have one or two of those on the shelf in good shape (i.e. not cracked in half)... If you were coming down for the BBQ we could wheel and deal for the price. (or if you trust a local that might make it this way...)

One thing to note, not all clutch fans are created equal, I had to replace the clutch unit I stole from a 1978 super sixed A/C Volare Wagon and put on the Hpak Duster... I had ordered an aftermarket one for a slant six Volare, and the clutch 'nose'/thermostatic spring was about 1/2" too long (enough to make sure it would gouge the radiator....)... oddly a parts search found the 318 version was the same unit as the slant six one(riiiight), and the 360 version was different... installed the 360 unit and it was exactly like the old chrysler version I had.

Check your fitting immediately in case you need to return it.

-D.Idiot
Author:  AnotherSix [ Mon Jul 14, 2008 9:13 pm ]
Post subject: 
The stock fan that went with the 22" radiator shroud is 17", something to keep in mind when shopping.

I was at the junk yard last week looking for a clutch and fan and found nothing. One that looked good on a jeep, but it was counter clockwise. Oddly I found a super six setup, that would have never happened if I was looking for one.

On our car there is only about 3 & 1/8" from the pump to the core. Dan, is that chrysler clutch short enough for this? The power steering pulleys make fan pitch an issue as well.
Author:  SlantSixDan [ Tue Jul 15, 2008 7:01 am ]
Post subject: 
Mmmm...no, I don't think it'll fit. Seems to me the 4266 665 is about 3½" deep overall. There's 4095 853 (HD) and 4167 771 (standard duty) which might be slightly shorter overall, but as I say, it can get really tough finding a clutch that'll fit between a slant-6 and the radiator.

If you've got good wrecking yards locally, this clutch fan setup off a Mercedes looks like just the ticket to solve the fitment problem. If no good yards locally, www.car-part.com comes up with a ton of hits when you search for a 1977 Mercedes 280 "fan blade".
Author:  AnotherSix [ Tue Jul 15, 2008 9:06 am ]
Post subject: 
Thanks Dan.

Just another 1/4" would "open" things up. I am hitting dead ends with electric fans worth using as well. Maybe some low profile flex-a-lite 12 inch fans can be made to work, but I have not found any technical drawings and have not had time to go somewhere to look at them. I am not sure if they are shorter around the perimeter or are flat. Electric has been my first choice, with a clutch fan second.

I work in LA and drive past Sun Valley every day, so a mercedes fan would be around. I just have to find it.

I just finished the AC install on our car and it works real well, I would just like to get something other than the stock solid 7 blade fan.
Author:  Valleyant [ Tue Jul 15, 2008 10:16 am ]
Post subject: 
Hi,
Last time I was out at the yard I was looking for a clutch fan for my '72 Valiant. I pulled one from a 318 Diplomat and it turned out to be to big....it would definately contact the radiator...BUT a concern I have is their heavy weight compared to the stock fixed blade fan. Will the heavier weight cause problems with the water pump bearing? Thanks, nico
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