New fan clutch
July 14th, 2014, 02:11 PM
#1
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New fan clutch
How long should a new fan clutch stay engaged when the motor is first started? Mine seems to stay hooked up for a good five minutes before letting go.
350 auto w/air
350 auto w/air
July 14th, 2014, 05:33 PM
#3
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In short, the clutch should not be engaged or engaged fully when the car is first started and then become engaged as the engine warms up, not the other way around.
The clutch should also disengage the fan when the car is moving as the movement of the car pushes air through the radiator, and the fan is not needed. In such cases, I think the fan just freewheels.
I've had three fan clutches fail on me over the years. In one case, the fan clutch failed by seizing up, and whenever the car was going more than about 20 miles an hour, a roaring sound like a jet engine came from the engine compartment. The problem was that the fan was spinning way too fast, and a new fan clutch fixed it.
The other two times were the opposite problem. The clutch would never engage, and even when the car was fully warm and idling in Park, the fan, which should have been spinning rapidly to cool the hot engine, was turning slowly, and you could almost stop it with your fingers (not that I tried).
See the first paragraph under "Function" on this page:
http://en.wikipedia.org/wiki/Fan_clutch
July 14th, 2014, 06:14 PM
#4
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That is totally normal operation per the Hayden web site:
http://www.haydenauto.com/upload/Hay...n-clutches.pdf
A thermal fan clutch is engaged on a cold startup because the fluid drains into the
working area when the engine is shut off. The fan clutch will slow down shortly after
startup as a result of a pumping action produced by a difference
in speed between the shaft and the body of the clutch.
http://www.haydenauto.com/upload/Hay...n-clutches.pdf
A thermal fan clutch is engaged on a cold startup because the fluid drains into the
working area when the engine is shut off. The fan clutch will slow down shortly after
startup as a result of a pumping action produced by a difference
in speed between the shaft and the body of the clutch.
July 14th, 2014, 06:29 PM
#5
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The fan clutch will be engaged the first few minutes after a cold start, until the silicone fluid inside disperses. There is an explanation in the CSM.
Of three new clutches I have used from 3 mfrs on the 72, all are engaged at start and they fluctuate from engaged to disengaged for under 5 minutes at idle.
The stock one on my 86 is fully engaged for about 5 seconds at a cold start at fast idle, then simmers down. After then it runs normal.
Idle speed will affect the fluid distribution time. My 72 lacks a very fast fast-idle speed like my 86 has, so that has something to do with its longer cycling on cold startup.
Of three new clutches I have used from 3 mfrs on the 72, all are engaged at start and they fluctuate from engaged to disengaged for under 5 minutes at idle.
The stock one on my 86 is fully engaged for about 5 seconds at a cold start at fast idle, then simmers down. After then it runs normal.
Idle speed will affect the fluid distribution time. My 72 lacks a very fast fast-idle speed like my 86 has, so that has something to do with its longer cycling on cold startup.
July 14th, 2014, 06:41 PM
#6
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Yes, I read the description in the CSM and online but nothing really specified how long it took for the oil to get where it needed to be. I just wanted to make sure I didn't need to return it before the return expired.
Eric, I was thinking more like a Cessna, lol.
Eric, I was thinking more like a Cessna, lol.
July 14th, 2014, 08:15 PM
#7
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The super heavy duty Hayden clutch in my car doesn't fully disengage for 15-20 minutes.
I'm considering getting a regular heavy duty clutch, but this one kicks butt in traffic jams.
- Eric
I'm considering getting a regular heavy duty clutch, but this one kicks butt in traffic jams.
- Eric
July 14th, 2014, 08:52 PM
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July 17th, 2014, 07:22 PM
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My 71 has what I believe is the original fan clutch on it. On my vista I just changed it back to a original type fan that I got off a parts car. The used clutch was bad, it barely turned at idle and free wheeled quite a while after being shut off. So I replaced the clutch w/ a generic. Now I notice it also takes a while to disengage. You definitely can hear it and can tell when it engages. My original one on the 71 I never noticed being noisy ever..
July 17th, 2014, 09:08 PM
#12
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My 71 has what I believe is the original fan clutch on it. On my vista I just changed it back to a original type fan that I got off a parts car. The used clutch was bad, it barely turned at idle and free wheeled quite a while after being shut off. So I replaced the clutch w/ a generic. Now I notice it also takes a while to disengage. You definitely can hear it and can tell when it engages. My original one on the 71 I never noticed being noisy ever..
August 12th, 2014, 05:01 AM
#13
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I drove the Cutlass to school this morning. A sort of farewell to summer. A 25 minute drive, 15 of them interstate at 65mph and the clutch was still fully engaged when I pulled in the lot and shut her down. That doesn't seems right, and was quite annoying at 65. It's 61 degrees this morning but still, 25 minutes of blacktop and interstate?
August 12th, 2014, 06:39 AM
#14
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The purpose of the fan clutch is to engage the fan when the engine reaches a certain temperature but the car is not moving or moving fast enough to draw air through the radiator.
When you're speeding down the interstate at 65 mph, there is plenty of air flowing through the radiator due to car's forward motion, so the fan is not needed, and the clutch disengages. When you pull off the highway and are idling at a stoplight at the end of the exit ramp or are creeping along in the parking lot at 5 mph looking for a parking space, there is little to no air flow through the radiator, so the temperature of the engine begins to rise, and the fan clutch engages to draw more air through the radiator. So your fan clutch should be engaged as you pull into the parking space, shift into Park, and shut down the engine.
The fan clutch should not engage when the engine is first started because the engine is cold. As it warms up, as long as the car is not moving, it should eventually engage. However, this is from the '73 chassis service manual regarding clutch noise at start-up:
"Fan noise is evident under the following normal conditions:
a. When the clutch is engaged for maximum cooling.
b. During the first few minutes after start-up until the clutch can redistribute the silicone fluid back to its normal disengaged operating condition after setting overnight."
Note the second one. Fan clutch noise can be expected at initial start-up, but it should go away after several minutes. You said in your initial post that the fan clutch stays engaged "for a good five minutes" at start-up. Sounds perfectly normal.
The manual goes on to say:
"However, fan noise or an excessive roar will generally occur continuously under all high engine speed conditions (2500 rpm and up) if the clutch assembly is locked up due to an internal failure. If the fan cannot be rotated by hand or there is a rough grating feel as the fan is turned, the clutch should be replaced."
The bottom line here is, an engaged fan clutch at operating temperature while the car is idling or moving slowly is normal regardless of how long the engine has been running. If you're hearing a roaring sound as you're cruising down the interstate, replace the fan clutch.
Last edited by jaunty75; August 12th, 2014 at 06:47 AM.
August 12th, 2014, 11:08 AM
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August 12th, 2014, 02:09 PM
#16
I think this is normal. I think that people are misunderstanding the operation of a fan clutch. It does not depend on how long the engine has been running. It depends on engine temperature.
The purpose of the fan clutch is to engage the fan when the engine reaches a certain temperature but the car is not moving or moving fast enough to draw air through the radiator.
When you're speeding down the interstate at 65 mph, there is plenty of air flowing through the radiator due to car's forward motion, so the fan is not needed, and the clutch disengages. When you pull off the highway and are idling at a stoplight at the end of the exit ramp or are creeping along in the parking lot at 5 mph looking for a parking space, there is little to no air flow through the radiator, so the temperature of the engine begins to rise, and the fan clutch engages to draw more air through the radiator. So your fan clutch should be engaged as you pull into the parking space, shift into Park, and shut down the engine.
The fan clutch should not engage when the engine is first started because the engine is cold. As it warms up, as long as the car is not moving, it should eventually engage. However, this is from the '73 chassis service manual regarding clutch noise at start-up:
"Fan noise is evident under the following normal conditions:
a. When the clutch is engaged for maximum cooling.
b. During the first few minutes after start-up until the clutch can redistribute the silicone fluid back to its normal disengaged operating condition after setting overnight."
Note the second one. Fan clutch noise can be expected at initial start-up, but it should go away after several minutes. You said in your initial post that the fan clutch stays engaged "for a good five minutes" at start-up. Sounds perfectly normal.
The manual goes on to say:
"However, fan noise or an excessive roar will generally occur continuously under all high engine speed conditions (2500 rpm and up) if the clutch assembly is locked up due to an internal failure. If the fan cannot be rotated by hand or there is a rough grating feel as the fan is turned, the clutch should be replaced."
The bottom line here is, an engaged fan clutch at operating temperature while the car is idling or moving slowly is normal regardless of how long the engine has been running. If you're hearing a roaring sound as you're cruising down the interstate, replace the fan clutch.
The purpose of the fan clutch is to engage the fan when the engine reaches a certain temperature but the car is not moving or moving fast enough to draw air through the radiator.
When you're speeding down the interstate at 65 mph, there is plenty of air flowing through the radiator due to car's forward motion, so the fan is not needed, and the clutch disengages. When you pull off the highway and are idling at a stoplight at the end of the exit ramp or are creeping along in the parking lot at 5 mph looking for a parking space, there is little to no air flow through the radiator, so the temperature of the engine begins to rise, and the fan clutch engages to draw more air through the radiator. So your fan clutch should be engaged as you pull into the parking space, shift into Park, and shut down the engine.
The fan clutch should not engage when the engine is first started because the engine is cold. As it warms up, as long as the car is not moving, it should eventually engage. However, this is from the '73 chassis service manual regarding clutch noise at start-up:
"Fan noise is evident under the following normal conditions:
a. When the clutch is engaged for maximum cooling.
b. During the first few minutes after start-up until the clutch can redistribute the silicone fluid back to its normal disengaged operating condition after setting overnight."
Note the second one. Fan clutch noise can be expected at initial start-up, but it should go away after several minutes. You said in your initial post that the fan clutch stays engaged "for a good five minutes" at start-up. Sounds perfectly normal.
The manual goes on to say:
"However, fan noise or an excessive roar will generally occur continuously under all high engine speed conditions (2500 rpm and up) if the clutch assembly is locked up due to an internal failure. If the fan cannot be rotated by hand or there is a rough grating feel as the fan is turned, the clutch should be replaced."
The bottom line here is, an engaged fan clutch at operating temperature while the car is idling or moving slowly is normal regardless of how long the engine has been running. If you're hearing a roaring sound as you're cruising down the interstate, replace the fan clutch.
A very concise, easy to understand explanation. Thank you.
August 12th, 2014, 02:42 PM
#17
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It does say heavy duty so I guess that's a good thing. This was my first trip to town on a cool day. On a warm day it's quiet by the time I get there. I suppose the oil is just thicker when cool and takes longer to disperse. Tonight it was quiet when I got home. I'll keep and eye (or ear) on it.
Thanks guys
August 12th, 2014, 03:26 PM
#18
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http://www.jcwhitney.com/replacement...12060y1971g2j1
It does say heavy duty so I guess that's a good thing. This was my first trip to town on a cool day. On a warm day it's quiet by the time I get there. I suppose the oil is just thicker when cool and takes longer to disperse. Tonight it was quiet when I got home. I'll keep and eye (or ear) on it.
Thanks guys
It does say heavy duty so I guess that's a good thing. This was my first trip to town on a cool day. On a warm day it's quiet by the time I get there. I suppose the oil is just thicker when cool and takes longer to disperse. Tonight it was quiet when I got home. I'll keep and eye (or ear) on it.
Thanks guys
August 12th, 2014, 04:06 PM
#19
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Maybe you're in the clear. If you have the stock six-blade fan, then going to a heavy duty fan clutch could very well be causing your problem. I went through this last year with my '72, and others on this forum have too. I tried the Imperial brand heavy duty clutch (same part as the Hayden 2747 but a lot cheaper), and it would take at least five minutes on a cold start for the fan to quiet down, but at speed it would start roaring again. I swapped it for a standard clutch and problem solved.
August 12th, 2014, 06:19 PM
#20
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The new clutch I used from the parts place long ago seemed to do what you describe.
Over an hour and a half I heard the fan roar on the highway. I finally pulled into a gas station to check it. Not locked and measured engine temp was 150*.
The next time I drove the car, it acted normal.
Fan clutches are supposed to be stored flat side down, so I speculate that storing them say upside down could have caused the fluid to go where it was not supposed to and take longer to disperse where it should...
Over an hour and a half I heard the fan roar on the highway. I finally pulled into a gas station to check it. Not locked and measured engine temp was 150*.
The next time I drove the car, it acted normal.
Fan clutches are supposed to be stored flat side down, so I speculate that storing them say upside down could have caused the fluid to go where it was not supposed to and take longer to disperse where it should...
August 12th, 2014, 07:00 PM
#21
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Why did you buy a questionable "cheap" clutch from JCWhitney, Mac? The right part is $16 cheaper at NAPA.
I agree with Rob - it may settle out and be fine. If not, Hayden makes high quality clutches, and I'd go for one of theirs.
To give a slightly different explanation of the fan clutch:
A fan clutch is designed to allow for the transmission of a certain amount of torque from the water pump pulley to the fan, depending upon the temperature.
Once the clutch warms up (or the fluid redistributes), it will begin to work as specified, which is to say that it will transmit almost all torque through when hot, and very little of it when cold.
Since the fan moves air, its movement is resisted by air, and is resisted more as its speed increases. Its movement is also resisted more by a fan that is larger, has a steeper pitch, or has more blades. A fan clutch that sees more resistance will transmit less movement (though the same torque) than one that sees less resistance, so that if you have a clutch that is originally designed for a heavy truck with a huge fan, it will hook up tight to a smaller fan, and spin it like an airplane propeller, and if you have a clutch originally designed for a small fan in a small car, it will barely turn a larger fan in a larger car, and you will overheat.
The clutch needs to be matched to the fan used on it, as well as to the rest of the application.
Only you can judge whether your clutch is operating correctly, or satisfactorily.
- Eric
I agree with Rob - it may settle out and be fine. If not, Hayden makes high quality clutches, and I'd go for one of theirs.
To give a slightly different explanation of the fan clutch:
A fan clutch is designed to allow for the transmission of a certain amount of torque from the water pump pulley to the fan, depending upon the temperature.
Once the clutch warms up (or the fluid redistributes), it will begin to work as specified, which is to say that it will transmit almost all torque through when hot, and very little of it when cold.
Since the fan moves air, its movement is resisted by air, and is resisted more as its speed increases. Its movement is also resisted more by a fan that is larger, has a steeper pitch, or has more blades. A fan clutch that sees more resistance will transmit less movement (though the same torque) than one that sees less resistance, so that if you have a clutch that is originally designed for a heavy truck with a huge fan, it will hook up tight to a smaller fan, and spin it like an airplane propeller, and if you have a clutch originally designed for a small fan in a small car, it will barely turn a larger fan in a larger car, and you will overheat.
The clutch needs to be matched to the fan used on it, as well as to the rest of the application.
Only you can judge whether your clutch is operating correctly, or satisfactorily.
- Eric
August 12th, 2014, 07:01 PM
#22
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The new clutch I used from the parts place long ago seemed to do what you describe.
Over an hour and a half I heard the fan roar on the highway. I finally pulled into a gas station to check it. Not locked and measured engine temp was 150*.
The next time I drove the car, it acted normal.
Fan clutches are supposed to be stored flat side down, so I speculate that storing them say upside down could have caused the fluid to go where it was not supposed to and take longer to disperse where it should...
Over an hour and a half I heard the fan roar on the highway. I finally pulled into a gas station to check it. Not locked and measured engine temp was 150*.
The next time I drove the car, it acted normal.
Fan clutches are supposed to be stored flat side down, so I speculate that storing them say upside down could have caused the fluid to go where it was not supposed to and take longer to disperse where it should...
August 13th, 2014, 05:21 AM
#23
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Why did you buy a questionable "cheap" clutch from JCWhitney, Mac? The right part is $16 cheaper at NAPA.
I agree with Rob - it may settle out and be fine. If not, Hayden makes high quality clutches, and I'd go for one of theirs.
To give a slightly different explanation of the fan clutch:
A fan clutch is designed to allow for the transmission of a certain amount of torque from the water pump pulley to the fan, depending upon the temperature.
Once the clutch warms up (or the fluid redistributes), it will begin to work as specified, which is to say that it will transmit almost all torque through when hot, and very little of it when cold.
Since the fan moves air, its movement is resisted by air, and is resisted more as its speed increases. Its movement is also resisted more by a fan that is larger, has a steeper pitch, or has more blades. A fan clutch that sees more resistance will transmit less movement (though the same torque) than one that sees less resistance, so that if you have a clutch that is originally designed for a heavy truck with a huge fan, it will hook up tight to a smaller fan, and spin it like an airplane propeller, and if you have a clutch originally designed for a small fan in a small car, it will barely turn a larger fan in a larger car, and you will overheat.
The clutch needs to be matched to the fan used on it, as well as to the rest of the application.
Only you can judge whether your clutch is operating correctly, or satisfactorily.
- Eric
I agree with Rob - it may settle out and be fine. If not, Hayden makes high quality clutches, and I'd go for one of theirs.
To give a slightly different explanation of the fan clutch:
A fan clutch is designed to allow for the transmission of a certain amount of torque from the water pump pulley to the fan, depending upon the temperature.
Once the clutch warms up (or the fluid redistributes), it will begin to work as specified, which is to say that it will transmit almost all torque through when hot, and very little of it when cold.
Since the fan moves air, its movement is resisted by air, and is resisted more as its speed increases. Its movement is also resisted more by a fan that is larger, has a steeper pitch, or has more blades. A fan clutch that sees more resistance will transmit less movement (though the same torque) than one that sees less resistance, so that if you have a clutch that is originally designed for a heavy truck with a huge fan, it will hook up tight to a smaller fan, and spin it like an airplane propeller, and if you have a clutch originally designed for a small fan in a small car, it will barely turn a larger fan in a larger car, and you will overheat.
The clutch needs to be matched to the fan used on it, as well as to the rest of the application.
Only you can judge whether your clutch is operating correctly, or satisfactorily.
- Eric
Ain't no thang. It's an easy enough swap. But thanks for the explanation.
August 13th, 2014, 05:41 AM
#24
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I suppose my recommendation would be to run this one for a while and see if it quiets down.
If not, I'd buy a non-heavy-duty one and see how you like that.
You can always swap the heavy one back for the hottest summer days.
- Eric
August 14th, 2014, 05:44 PM
#25
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August 15th, 2014, 05:18 PM
#26
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I have a good Hayden HD clutch with few hundred miles on it if you are interested.
This one is great for in town puttering in hot weather.
I am happier with the STD one for long cruises as it is quieter. .
This one is great for in town puttering in hot weather.
I am happier with the STD one for long cruises as it is quieter. .
August 17th, 2014, 05:09 PM
#27
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Thanks for the offer Rob but I already have a HD. And for right now it seems to be behaving. If I get another it will be standard.
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