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Has anyone ever replaced the fan clutch with a fixed fan? [message #247953] Sun, 20 April 2014 12:40 Go to next message
Otterwan   United States
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With all the talk of fan clutches lately it got me thinking. Back in the day when we were poor college kids, replacing a fan clutch was not in the budget. Instead we would get a large "flex fan" from the local Al's Auto parts and run that instead. I had one of these on a 396 in a 1970 GMC truck for 22 years, hauling boats, campers, etc., and never had a heat issue.

Has anyone ever tried this on a GMC?


1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
Re: Has anyone ever replaced the fan clutch with a fixed fan? [message #247954 is a reply to message #247953] Sun, 20 April 2014 12:48 Go to previous messageGo to next message
Larry is currently offline  Larry   United States
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Otterwan wrote on Sun, 20 April 2014 12:40

With all the talk of fan clutches lately it got me thinking. Back in the day when we were poor college kids, replacing a fan clutch was not in the budget. Instead we would get a large "flex fan" from the local Al's Auto parts and run that instead. I had one of these on a 396 in a 1970 GMC truck for 22 years, hauling boats, campers, etc., and never had a heat issue.

Has anyone ever tried this on a GMC?

I don't know of anyone who has tried it , but you know how the fan "ROARS" when it gets hot enough to engage? Well, I think that is what you would hear with a fixed flex fan. Additionally, with that extra drag on the motor, your gas milage might be negatively effected. IMO, it is worth having that clutch in place and working. JWIT


Larry Smile
78 Royale w/500 Caddy
Menomonie, WI.
Re: Has anyone ever replaced the fan clutch with a fixed fan? [message #247957 is a reply to message #247953] Sun, 20 April 2014 13:18 Go to previous messageGo to next message
Kirk is currently offline  Kirk   United States
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Bert & Fay run a flex fan.

Kirk & Eloise Yeager - Motorcyclists/RVers/Dog Lovers - 77 Royale 455/TBI/3:55 - 49ers - N. Nevada - NdnKirk at Gmail dot com
Re: Has anyone ever replaced the fan clutch with a fixed fan? [message #247960 is a reply to message #247953] Sun, 20 April 2014 14:06 Go to previous messageGo to next message
Bob de Kruyff   United States
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Otterwan wrote on Sun, 20 April 2014 11:40

With all the talk of fan clutches lately it got me thinking. Back in the day when we were poor college kids, replacing a fan clutch was not in the budget. Instead we would get a large "flex fan" from the local Al's Auto parts and run that instead. I had one of these on a 396 in a 1970 GMC truck for 22 years, hauling boats, campers, etc., and never had a heat issue.

Has anyone ever tried this on a GMC?

I can't recall which engine it was, but we had a very quiet flex fan on one of our truck models. I suspect it may have been a 4.3 v6 on a 1/2 ton. You just have to find the right combination.


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: Has anyone ever replaced the fan clutch with a fixed fan? [message #247962 is a reply to message #247953] Sun, 20 April 2014 14:11 Go to previous messageGo to next message
armandminnie is currently offline  armandminnie   United States
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I had to drive from LA to Palm Springs one day a couple of years ago with a "fixed fan" due to a seized-up fan clutch. I don't want to do that again - you won't either.

Armand Minnie
Marana, AZ
'76 Eleganza II TZE166V103202
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Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixed fan? [message #247964 is a reply to message #247960] Sun, 20 April 2014 14:15 Go to previous messageGo to next message
Gary Berry is currently offline  Gary Berry   United States
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What I found out about the flex fan is that they flatten out at high RPMs
(which is what they are suppose to do). But, when you have to downshift to
second or first while going up a mountain and you're running the engine at
higher RPMs and it's hot out and you're going slow then you lose the
cooling ability of the fan.

Gary Berry
Prosser, WA
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Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixed fan? [message #247970 is a reply to message #247964] Sun, 20 April 2014 16:41 Go to previous messageGo to next message
Bob de Kruyff   United States
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Gary Berry wrote on Sun, 20 April 2014 13:15

What I found out about the flex fan is that they flatten out at high RPMs
(which is what they are suppose to do). But, when you have to downshift to
second or first while going up a mountain and you're running the engine at
higher RPMs and it's hot out and you're going slow then you lose the
cooling ability of the fan.

Gary Berry
Prosser, WA
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Good point !


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixed fan? [message #247973 is a reply to message #247970] Sun, 20 April 2014 16:47 Go to previous messageGo to next message
Bob de Kruyff   United States
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Bob de Kruyff wrote on Sun, 20 April 2014 15:41

Gary Berry wrote on Sun, 20 April 2014 13:15

What I found out about the flex fan is that they flatten out at high RPMs
(which is what they are suppose to do). But, when you have to downshift to
second or first while going up a mountain and you're running the engine at
higher RPMs and it's hot out and you're going slow then you lose the
cooling ability of the fan.

Gary Berry
Prosser, WA
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Good point !

BTW that reminds me of some research we did in the late 90's concerning fan noise. We were able to reduce the engaged fan noise to the extent that you couldn't tell it was on. It still consumes fuel of course. This did not reduce effectiveness. If anyone has the energy, I'm sure a late model truck fan that fits our coaches will be a good thing to have.


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixed fan? [message #247978 is a reply to message #247973] Sun, 20 April 2014 17:38 Go to previous messageGo to next message
sgltrac is currently offline  sgltrac   United States
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Say maybe off a 7.3 ford diesel Bob?

Todd Sullivan

Sully
77 royale
Seattle

> On Apr 20, 2014, at 2:47 PM, Bob de Kruyff <NEXT2POOL@AOL.COM> wrote:
>
>
>
> Bob de Kruyff wrote on Sun, 20 April 2014 15:41
>> Gary Berry wrote on Sun, 20 April 2014 13:15
>>> What I found out about the flex fan is that they flatten out at high RPMs
>>> (which is what they are suppose to do). But, when you have to downshift to
>>> second or first while going up a mountain and you're running the engine at
>>> higher RPMs and it's hot out and you're going slow then you lose the
>>> cooling ability of the fan.
>>>
>>> Gary Berry
>>> Prosser, WA
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> Good point !
>
> BTW that reminds me of some research we did in the late 90's concerning fan noise. We were able to reduce the engaged fan noise to the extent that you couldn't tell it was on. It still consumes fuel of course. This did not reduce effectiveness. If anyone has the energy, I'm sure a late model truck fan that fits our coaches will be a good thing to have.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
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Sully 77 Royale basket case. Future motorhome land speed record holder(bucket list) Seattle, Wa.
Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixedfan? [message #247989 is a reply to message #247973] Sun, 20 April 2014 18:03 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
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Bob,

As noted in the text below the photo I bought one of these off eBay to help cool the Caddy 500 I've got. Gary Kosier gave me a photo
of the gold painted Caddy 500 at the GM Heritage museum that has one of these fans on it which has a clutch! I have yet to find the
clutch part number. The fan I have will have to be modified to make the clutch fit.

I can't remember if it was Gary or someone else that told me these fans were used on Caddy 500's in ambulances or hearses.

http://www.gmcmhphotos.com/photos/showgallery.php?cat=6533

It is a GM product!

Regards,
Rob M.

-----Original Message-----
From: Bob de Kruyff

BTW that reminds me of some research we did in the late 90's concerning fan noise. We were able to reduce the engaged fan noise to
the extent that you couldn't tell it was on. It still consumes fuel of course. This did not reduce effectiveness. If anyone has the
energy, I'm sure a late model truck fan that fits our coaches will be a good thing to have.
--
Bob

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426
Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixedfan? [message #247991 is a reply to message #247989] Sun, 20 April 2014 18:26 Go to previous messageGo to next message
Otterwan   United States
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Rob - That looks almost exactly like the fan I had on my 396. I remember how odd the blade spacing seemed.

1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixedfan? [message #248027 is a reply to message #247989] Sun, 20 April 2014 21:11 Go to previous messageGo to next message
Bob de Kruyff   United States
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USAussie wrote on Sun, 20 April 2014 17:03

Bob,

As noted in the text below the photo I bought one of these off eBay to help cool the Caddy 500 I've got. Gary Kosier gave me a photo
of the gold painted Caddy 500 at the GM Heritage museum that has one of these fans on it which has a clutch! I have yet to find the
clutch part number. The fan I have will have to be modified to make the clutch fit.

I can't remember if it was Gary or someone else that told me these fans were used on Caddy 500's in ambulances or hearses.

http://www.gmcmhphotos.com/photos/showgallery.php?cat=6533

It is a GM product!

Regards,
Rob M.

-----Original Message-----
From: Bob de Kruyff

BTW that reminds me of some research we did in the late 90's concerning fan noise. We were able to reduce the engaged fan noise to
the extent that you couldn't tell it was on. It still consumes fuel of course. This did not reduce effectiveness. If anyone has the
energy, I'm sure a late model truck fan that fits our coaches will be a good thing to have.
--
Bob

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Rob--the science really didn't really progress untill 1996 so I doubt any Cad 500 applications will work adequately.


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixedfan? [message #248060 is a reply to message #248027] Mon, 21 April 2014 11:40 Go to previous messageGo to next message
Keith V is currently offline  Keith V   United States
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Car craft did some dyno testing on different fans, the clutch fan was almost as good as no fan
flex fans were single digit horsepower IIRC

Here it is...http://www.network54.com/Forum/215655/message/1066184641/Car+Craft+Cooling+Fan+Dyno+Test


Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
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Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixedfan? [message #248061 is a reply to message #248060] Mon, 21 April 2014 11:41 Go to previous messageGo to next message
Keith V is currently offline  Keith V   United States
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Keith V wrote on Mon, 21 April 2014 11:40

Car craft did some dyno testing on different fans, the clutch fan was almost as good as no fan
flex fans were single digit horsepower IIRC

Fixed url...



Here it http://www.network54.com/Forum/215655/message/1066184641/Car+Craft+Cooling+Fan+Dyno+Test


Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
Re: [GMCnet] Has anyone ever replaced the fan clutch with a fixedfan? [message #248066 is a reply to message #248061] Mon, 21 April 2014 12:18 Go to previous message
Otterwan   United States
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That is a great comparison, thanks!

1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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