Home » Public Forums » GMCnet » fan clutch
| fan clutch [message #169354] |
Sat, 12 May 2012 16:06  |
skip2
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
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I know it has been discussed before, but does anyone know exactly how and when the fan clutch should kick in. Mine has started to create hurricane Jimmy about 5 seconds after the motor starts and as far as my wasted hearing could tell it don't stop the gail force winds. Is there one fan clutch that is recommended over others. Thanks
Skip
74 Canyon Lands, FiTech,
3.7 FD LSD, Manny Tranny,
Springfield Distributor,
2001 Chevy Tracker Ragtop Towd
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| Re: [GMCnet] fan clutch [message #169356 is a reply to message #169354] |
Sat, 12 May 2012 16:39  |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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Skip,
It’s not too tough, but a lot of finger-tip work. I’ve done it on the side of the road (well, in a Hotel parking lot) in less than an hour.
If your clutch is locked up, it’s about to fail.
If your clutch does not roar when the engine starts, it’s about to fail.
I used whatever Jim K recommended, not the heavy duty one. I’d still like to replace the steel fan with a plastic one. I wonder if our fan clutches cross-reference to anything modern?
Larry Davick
The Mystery Machine
Fremont, CA
On May 12, 2012, at 2:06 PM, Skip Hartline wrote:
>
>
> I know it has been discussed before, but does anyone know exactly how and when the fan clutch should kick in. Mine has started to create hurricane Jimmy about 5 seconds after the motor starts and as far as my wasted hearing could tell it don't stop the gail force winds. Is there one fan clutch that is recommended over others. Thanks
> Skip
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: fan clutch [message #169375 is a reply to message #169354] |
Sat, 12 May 2012 19:08 |
Luvn737s
Messages: 1106
Registered: June 2007
Karma: 2
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My guess (FWIW) is that fan clutches fail from long periods of sitting. If they were run at least monthly so that they engaged and disengaged, I think their lifespan would be greatly improved.
My gear wrench (1/2" maybe, but don't hold me to it) earned it's space in the toolbox for this job.
Randy
1973 26' Painted Desert
Ahwatukee (Phoenix) AZ
[Updated on: Sat, 12 May 2012 19:09] Report message to a moderator |
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| Re: fan clutch [message #169378 is a reply to message #169375] |
Sat, 12 May 2012 19:37 |
armandminnie
Messages: 864
Registered: May 2009
Location: Marana, AZ
Karma: 2
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Randy, my guess is that given how much the fan clutch is used in a standard GMC they wear out from overuse too. Fans are not supposed to run when driving at highway speeds and most GMC fans cycle on and off at highway speeds - mine did.
Armand Minnie
Marana, AZ
'76 Eleganza II TZE166V103202
visit my gmc blog
click here to visit gmcws.org
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| Re: fan clutch [message #169389 is a reply to message #169382] |
Sat, 12 May 2012 21:45 |
Jon payne
Messages: 495
Registered: May 2008
Karma: 1
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So where can one get a AC Delco 154644? I have tried Napa ,Auto Zone, Rock Auto, Oreillys and Summit. None carry this PN also tried PN as 15-4644..
Jon
Jon Payne
76 Palm Beach
Westfield,IN
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| Re: [GMCnet] fan clutch [message #169398 is a reply to message #169371] |
Sun, 13 May 2012 01:58 |
Chuck Garton
Messages: 54
Registered: June 2006
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I went to the NAPAOnline Website. On the main page inthe upper right
is a part number enter.
One can enter a NAPA number or sombody elses part number by checking
the Interchange box.
From the Motorhome parts manual page 6-3, item 16, I entered 550528
(engine # 417794 1977 455).
It crossed over to NAPA # 261305. It was in stock and costs $21.60.
This must be a light duty clutch.
Years ago I installed radiator sides like Armond's and have cut out
the inner fenders on both sides.
I am runnung a Delco Heavy duty clutch and it runs a lot.
My engine is out right now. I am going to install a lower baffel like Armond's.
And for $21.60 + tax, I am going to try the light duty clutch.
I live in the Mojave Desert, so I'll be able to check it on a hot day
Chuck Garton 1977
Kingsley 455
Ridgecrest, CA
On Sat, May 12, 2012 at 4:50 PM, Armand Minnie <armand@minniebiz.com> wrote:
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>
> Read here http://minniebiz.com/gmcmotorhome/?p=744 too.
> --
> Armand Minnie
> Marana, AZ
> '76 Eleganza II
> TZE166V103202
> http://www.minniebiz.com/gmcmotorhome
> use the forum - it's easy
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| Re: fan clutch [message #169399 is a reply to message #169378] |
Sun, 13 May 2012 02:21 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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15-4208 is the OEM Clutch.
It is available here and at other locations:
https://acdelcooutlet.com/index.php/15-4208.html
The 15-4644 is a much heavier and noisier clutch. If you like noise and have good condition, correct width 7/16" fan belts, then feel free to go to the 14-4644. Otherwise go with the standard 15-4208.
The correct belt for a 15-4644 (which we do not have on a GMC) is a pair of 1/2 inch wide belts. Many GMCers use the 15-4644 with 7/16" belts and love the noise.
I also know many GMCers (including me) that use the 15-4208 standard duty clutch.
We have beat this subject (like tire wars and ignition advance) to death in the past so that is all I'll say.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] fan clutch [message #169412 is a reply to message #169398] |
Sun, 13 May 2012 08:42 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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| Chuck Garton wrote on Sun, 13 May 2012 01:58 |
I went to the NAPAOnline Website. On the main page inthe upper right
is a part number enter.
One can enter a NAPA number or sombody elses part number by checking
the Interchange box.
From the Motorhome parts manual page 6-3, item 16, I entered 550528
(engine # 417794 1977 455).
It crossed over to NAPA # 261305. It was in stock and costs $21.60.
This must be a light duty clutch.
Years ago I installed radiator sides like Armond's and have cut out
the inner fenders on both sides.
I am runnung a Delco Heavy duty clutch and it runs a lot.
My engine is out right now. I am going to install a lower baffel like Armond's.
And for $21.60 + tax, I am going to try the light duty clutch.
I live in the Mojave Desert, so I'll be able to check it on a hot day
Chuck Garton 1977
Kingsley 455
Ridgecrest, CA
On Sat, May 12, 2012 at 4:50 PM, Armand Minnie <armand@minniebiz.com> wrote:
>
>
> Read here http://minniebiz.com/gmcmotorhome/?p=744 too.
> --
> Armand Minnie
> Marana, AZ
> '76 Eleganza II
> TZE166V103202
> http://www.minniebiz.com/gmcmotorhome
> use the forum - it's easy
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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So Chuck, why don't yall consider moving back east?
I am no expert and have little to add but I would check Armand's information. I have added the side flaps to our 74. I also had the lower air dam I got from Jim K. Had to take it off. With the Blaine Merrell radiator gaurd mine was just too low to the ground and kept hitting the pavement. I plan to use the same bracket and install a narrower air dam before it gets hot. Any air you can get up in there will help shut the noisy fan off. Also, like Chuck, I have air rushing out my inner fenders. Never run hot, but I like that fan shutting off when I hit 35 mph.
This is a very old topic with varying opinions on the correct chutch. You might give Jim K. a call if you do not locate one locally. I think mine came from Advance Auto.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: fan clutch [message #169414 is a reply to message #169354] |
Sun, 13 May 2012 09:40 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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After experiencing a lot of that fan clutch coming on....meaning...temps above 80* and the fan clutch coming on every 5-10 minutes or so, I took Bob Drews advice. I bought some rubber conveyer belt material from a local farm supply. I then built a funnel around the inside of the grill completely enclosing it, from the radiator (actually the AC condensor) on out to the grill itself. Now, once the air enters the grill, the only place it can go is through the radiator. It cannot go up, right, left or down and around. Now, even in the warmest weather, the fan clutch engages only on hot days in town, or sitting at an idle for long periods. This one mod did more for controlling temps than the aluminum radiator. Just my experience...
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: fan clutch [message #169415 is a reply to message #169414] |
Sun, 13 May 2012 10:00 |
bukzin
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
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| Larry wrote on Sun, 13 May 2012 07:40 |
After experiencing a lot of that fan clutch coming on....meaning...temps above 80* and the fan clutch coming on every 5-10 minutes or so, I took Bob Drews advice. I bought some rubber conveyer belt material from a local farm supply. I then built a funnel around the inside of the grill completely enclosing it, from the radiator (actually the AC condensor) on out to the grill itself. Now, once the air enters the grill, the only place it can go is through the radiator. It cannot go up, right, left or down and around. Now, even in the warmest weather, the fan clutch engages only on hot days in town, or sitting at an idle for long periods. This one mod did more for controlling temps than the aluminum radiator. Just my experience...
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Larry, Thanks for sharing.
Any way you could post some photos of you mod?
Bukzin
1977 Palm Beach
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| Re: [GMCnet] fan clutch [message #169434 is a reply to message #169414] |
Sun, 13 May 2012 14:02 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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When I bought the GMC, I'd previously had several motorhomes on Chevrolet
P-30 chassis. I was astounded at the lack of air flow control through the
'76 radiator. If you download this manual and read the section dedicated
to that topic, you'll see why:
http://www.bdub.net/manuals/P30/index.html
There's lots of other good generic information in that manual also,
particularly pertaining to automatic transmissions -- equally applicable to
the TH-425 as the 4L80 to which it specifically refers.
By far the best air flow control I've seen on a GMC was Barry Owens'. As a
NASCAR mechanic, he was very emphatic about the need and had an aluminum
duct from the grille to the radiator. Wish I had photos; if anyone's near
Lexington, NC, maybe you could visit him and take photos (IF he's still
tinkering with GMC's -- I haven't seen nor heard from him in 3 years or so).
Ken H.
On Sun, May 13, 2012 at 10:40 AM, Larry wrote:
>
>
> After experiencing a lot of that fan clutch coming on....meaning...temps
> above 80* and the fan clutch coming on every 5-10 minutes or so, I took Bob
> Drews advice. I bought some rubber conveyer belt material from a local
> farm supply. I then built a funnel around the inside of the grill
> completely enclosing it, from the radiator (actually the AC condensor) on
> out to the grill itself. Now, once the air enters the grill, the only
> place it can go is through the radiator. It cannot go up, right, left or
> down and around. Now, even in the warmest weather, the fan clutch engages
> only on hot days in town, or sitting at an idle for long periods. This one
> mod did more for controlling temps than the aluminum radiator. Just my
> experience...
> --
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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