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Mopar Fan Clutch

Mattfi1

Mattfi1

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I have a 68 Plymouth 440 and have a little overheating on it. I had installed a extra row of cores in the radiator but still overheating a little. I have looked in the repair manual for infor on the fan clutch. It does not tell me much about how to check it. Does anyone know what it should feel like when cool and sitting still. Should it free wheel? Or should it have resistance? Oh, no AC.
 
Daves69 said:
It should have some resistance to it and very little or no wobble in the blade IMO.
Some "cool" info here.............
http://www.mymopar.com/index.php?pid=440
Click to expand...
Thank you, I thought it should have some resistance, which it does not, so now have to determine which one I need and get it. Any ideas before a take it apart? Its on a 1968 Plymouth GTX convertible 440cu. in. four speed car without AC. Would be nice to have the correct part in hand and put it right on. Is there a way to tell if its a fluid drive unit? Like a fill plug or something I can see without disassembly. Can see much from most of the pictures.
 
Mattfi1 said:
Thank you, I thought it should have some resistance, which it does not, so now have to determine which one I need and get it. Any ideas before a take it apart? Its on a 1968 Plymouth GTX convertible 440cu. in. four speed car without AC. Would be nice to have the correct part in hand and put it right on. Is there a way to tell if its a fluid drive unit? Like a fill plug or something I can see without disassembly. Can see much from most of the pictures.
Click to expand...
The clutch has a flat front side without any spring showing. It also has a number on it but can't read it well. 010608s or 0706082.
 
Mattfi1 said:
I have a 68 Plymouth 440 and have a little overheating on it. I had installed a extra row of cores in the radiator but still overheating a little. I have looked in the repair manual for infor on the fan clutch. It does not tell me much about how to check it. Does anyone know what it should feel like when cool and sitting still. Should it free wheel? Or should it have resistance? Oh, no AC.
Click to expand...
I recall asking this question to Bob at Glen-ray Radiators. He told me a clutch fan should make about 3 revolutions when you spin it by hand while cold.
Your car should have a Thermo clutch and 18.5" fan #2863 216 if factory stock. Do you have a shroud?
 
i do have a shroud and the fan does spin some then stops. the fan, shroud and clutch are all original. Are we sure on a thermo clutch? The picture in the 68 manual shows a torque control fan drive the look more like it. The one picture is with a mirror in front of it. Or would the thermal control drive give me more cooling a idle and low speeds?

IMG_20170924_113128851.jpg IMG_20170924_113239439.jpg IMG_20170924_113930145.jpg
 
Last edited:
Mattfi1 said:
I have a 68 Plymouth 440 and have a little overheating on it.......
Click to expand...

Going back to post 1, "a little overheating" is a bit vague. Some more detail may help. Lots of stuff can have an effect.
Is your gauge reading correct? Maybe check it against another.
What temp and how old is your thermostat?
Is it to the point it's loosing coolant or just going higher temp than you are comfortable with?
Is the system and cap holding pressure?
Is your inlet radiator hose to the pump housing collapsing with RPM?
At highway speeds does the temp tend to come down compared to stop-n-go? The fan is almost irrelevant at high vehicle speed I believe.
Does the shroud fit the radiator and fan correctly?
BTW, An extra row of radiator tubes can reduce fan to radiator clearance. Too close and your fan could kiss the radiator.
 
The problem it is blowing fluid out after the gauge does above normal and also when I stop or park it. The thermostat is a new 195 and the water pump is also new following my rebuild. The cap is a new 12psi and holds pressure till I stop or park. The problem is only at low speeds or stop and go traffic. The gauge is normal at highway speeds.
IMG_20170418_101031189.jpg
The hoses are not collapsing and also are new. When I fill it up to within 1/2" of the top it will blow off enough to expose the top of the tubes. The original radiator was recently re-cored and a extra row of tubes were added. The timing is on and dwell is correct. As per the first picture I have enough room to put a mirror between the clutch and radiator. it also has the original shroud. I bought this car new. Just did a complete restoration but did not take apart the engine as it only has 52,000 miles on it.
 
As others have said, you probably should be using a 16psi cap and replace the 195 thermostat with a 180. Also on the thermo / non thermo clutch issue. I have read in a couple different write-ups that the Thermo unit is better than the non thermo in that it controls the temp better and lasts longer while supposedly giving you better gas mileage. I do know they cost more. For my money, I would use the thermo unit that the A/C cars have and go with a 180 degree thermostat & a 16psi cap to start with. The top of your tubes should not be exposed. Also, your fan looks awfully close to the radiator in your picture. Maybe with the extra core, you need a shorter shaft.
 
Hard to diagnose. If temperature spikes at idle, replace with the low profile Hayden listed above. 3 times cold seems like a lot. Use a temp gun to be sure of actual engine temperatures.
Mine was slipping and I could not diagnose it. When replaced, cool in traffic.
 
Rick62 said:
Here's an explanation of how fan clutches work. Note the differences between shaft speed and rotating speed on the various types. I found this very informative. http://www.haydenauto.com/featured products-fan clutches and fan blades/content.aspx
Click to expand...
All of the above. Are you sure u don`t have trapped air in the system? When u install the new stat, drill a couple of 1/8' holes just inside the perimeter, and have the front of the car up in the air when filling it, take ur time, let the air work out of it !
 
Having worked on cars for fifty years or so I've never had a problem with air lock in a cooling system. Maybe I'm just lucky? I usually fill the cooling system and run the car until coolant circulates without the radiator cap. After the coolant is circulating I top it off then install the cap. In the olden days my mentor taught me to do it this way. Could that make a difference?
 
The newer low profile clutch probably would cause clearance issues with the fan hitting the AC compressor if your car has AC. My car has a Sanden compressor and I installed the taller clutch before the short one was available. The fan has about 1/4" clearance from the front of the compressor.
 
themechanic said:
The newer low profile clutch probably would cause clearance issues with the fan hitting the AC compressor if your car has AC. My car has a Sanden compressor and I installed the taller clutch before the short one was available. The fan has about 1/4" clearance from the front of the compressor.
Click to expand...

I'm using a Sanden compressor and new short Hayden clutch on my '62 with air. I'm using the factory pulleys with belts in the stock location. The fan is slightly more than an inch away from the compressor clutch. Not sure what's different between your application and mine?? (picture attached)

fan.JPG
 
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