Fan Noise - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mdazb · 10-20-2004, 04:36 PM

Have 350 in my '72 C10 with a 4 blade cooling fan, w/o A/C. The fan roars when I'm at freeway speeds. When I rev. the motor by hand, it gets louder as the rpm's come down then the noise slows down. Would a fan clutch or a elect. fan be a better option or maybe a 6 blade fan?

Gordo · 10-20-2004, 05:52 PM

IMO a clutch fan would be a plus!

**Stocker** · 10-20-2004, 07:39 PM

A/C or not, I definitely recommend a clutch fan. Easy bolt-on, and should be cheap at the boneyard - just measure so you get one that fits. I prefer from later model truck or large (luxury) car. FWIW, I once had a flex-fan and my truck overheated with it.

skokie · 10-20-2004, 07:44 PM

What does a clutch fan do that quiets down the fan?

Thanks

mdazb · 10-20-2004, 08:04 PM

Great, the 4 blade fan is standard for a 350 or the 6 blade?

**Stocker** · 10-20-2004, 09:14 PM

Quote:

Originally Posted by mdazb

Great, the 4 blade fan is standard for a 350 or the 6 blade?

Mine's a seven blade...

**Stocker** · 10-20-2004, 09:11 PM

Quote:

Originally Posted by skokie

What does a clutch fan do that quiets down the fan?

The viscous thermal clutch allows the fan to free-wheel (okay, not quite) when extra cooling is not required - since the clutch isn't fully engaged, the fan rotates at a much slower speed, so it's pulling a lot less air - so you don't hear the roar of the fan.

mdazb · 10-20-2004, 09:56 PM

Stock?

68w/sbc406 · 10-20-2004, 09:59 PM

one of my friends had two clutch fans go bad on him with out warning. they chew up radiators pretty good

**Stocker** · 10-21-2004, 07:13 PM

Quote:

Originally Posted by mdazb

Stock?

Yes, as far as I know, but I bought the truck in 1977, so I can't be positive...

mdazb · 10-22-2004, 12:37 AM

What would be a good year car/truck to look for in a wrecking yard to rob a fan & clutch from?

68w/sbc406 · 10-22-2004, 08:49 PM

80s impalas or caprice.

Longhorn Man · 10-22-2004, 09:19 PM

Quote:

Originally Posted by mdazb

What would be a good year car/truck to look for in a wrecking yard to rob a fan & clutch from?

Depends on what water pump you have. (the bolt patern is not the same on short verses long water pump)
If you have a long pump, then you can pop the hood on any later model rear wheel drive V-8 chevy (that does NOT have serpentine belt drive) and rob it.
If you have the original short pump, (alt on drivers side) then you'll be hard pressed to find one in a junk yard...onless you find one with daul bolt paterns.

Longhorn Man · 10-20-2004, 10:21 PM

There was probably warning...he just never checked it. Every time I chainge my oil...and ever truck/van I service at work, I grab the top of the fan, and try to pull it towards the core support. If there is ANY play...it is time for a new one.
I also recomend a clutch and a 6 or 7 blade fan...but not a flex fan of any sort. Even the factory ones are junk. When the blades come off they go right through the hood.

skokie · 10-20-2004, 11:26 PM

Can someone post a pic of a fan with a clutch on it?

Thanks

**Yukon Jack** · 10-21-2004, 09:52 AM

Here is a pic of the clutch fan on my engine.

mdazb · 10-22-2004, 09:52 PM

Anywhere to get a new one?

jimfulco · 10-25-2004, 09:49 PM

Be sure you get the one with the thermal clutch in it. Those generally have a small coil on the front of the clutch. They pretty much freewheel unless the air coming through the radiator gets over a certain temperature, then the clutch engages & the fan blows hard. Non-thermal clutches are just a viscous drive, which makes the fan run at slightly less than full speed at all times, whether it's needed or not.

**Stocker** · 10-25-2004, 10:01 PM

Quote:

Originally Posted by jimfulco

Non-thermal clutches are just a viscous drive, which makes the fan run at slightly less than full speed at all times, whether it's needed or not.

This may be correct, but I'm not 100% sure it is. I believe the silicon fluid in clutch fans is thermally sensitive and its viscosity increases as the temperature rises, so the clutch will engage as required even if not equipped with the coil.

Eddie H. · 10-25-2004, 10:46 PM

A fan clutch will not only make a lot less noise, but it will also save some fuel.
You're wasting 5-10 horsepower turning a non-clutch type fan.

skokie · 10-26-2004, 12:09 AM

Does the parts stores carry a thermal clutch? Also is there one available for the 4 blade fan I have?

**Stocker** · 10-26-2004, 09:04 AM

Quote:

Originally Posted by skokie

Does the parts stores carry a thermal clutch? Also is there one available for the 4 blade fan I have?

Yes, they do carry replacement clutch units, and no, don't use your 4 blade fan. Clutch fans will have more blades and more pitch, so when the clutch engages, they can pull a lot of air, for improved cooling. Tour a boneyard and see what's on the vehicles - you'll get the idea.

skokie · 10-26-2004, 11:32 AM

Will do .

10-20-2004, 04:36 PM	#1
mdazb Registered User Join Date: Oct 2004 Location: Nor Cal Posts: 75	Fan Noise Have 350 in my '72 C10 with a 4 blade cooling fan, w/o A/C. The fan roars when I'm at freeway speeds. When I rev. the motor by hand, it gets louder as the rpm's come down then the noise slows down. Would a fan clutch or a elect. fan be a better option or maybe a 6 blade fan? __________________ --------------------------------- 72 C10 SWB 350 Work in progress 98 HD Fatboy 09 HD Heritage Softail 05 Honda Element

10-20-2004, 05:52 PM	#2
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	IMO a clutch fan would be a plus! __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

10-20-2004, 07:39 PM	#3
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,694	A/C or not, I definitely recommend a clutch fan. Easy bolt-on, and should be cheap at the boneyard - just measure so you get one that fits. I prefer from later model truck or large (luxury) car. FWIW, I once had a flex-fan and my truck overheated with it. __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

10-20-2004, 07:44 PM	#4
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,342	What does a clutch fan do that quiets down the fan? Thanks __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

10-20-2004, 08:04 PM	#5
mdazb Registered User Join Date: Oct 2004 Location: Nor Cal Posts: 75	Great, the 4 blade fan is standard for a 350 or the 6 blade? __________________ --------------------------------- 72 C10 SWB 350 Work in progress 98 HD Fatboy 09 HD Heritage Softail 05 Honda Element

10-20-2004, 09:56 PM	#8
mdazb Registered User Join Date: Oct 2004 Location: Nor Cal Posts: 75	Stock? __________________ --------------------------------- 72 C10 SWB 350 Work in progress 98 HD Fatboy 09 HD Heritage Softail 05 Honda Element

10-20-2004, 09:59 PM	#9
68w/sbc406 Got Light Emitting Diode? Join Date: Apr 2004 Location: Newberg, OR Posts: 2,485	one of my friends had two clutch fans go bad on him with out warning. they chew up radiators pretty good __________________ 1968 1/2 ton 2wd lwb 6 lug disc and bags up front. Next c notch and rear bags '02 Chevy Silverado LT ext cab short bed 2WD 5/7 drop on 22's(the family car) 1993 Cherokee work ride/weekend wheeler

10-22-2004, 12:37 AM	#11
mdazb Registered User Join Date: Oct 2004 Location: Nor Cal Posts: 75	What would be a good year car/truck to look for in a wrecking yard to rob a fan & clutch from? __________________ --------------------------------- 72 C10 SWB 350 Work in progress 98 HD Fatboy 09 HD Heritage Softail 05 Honda Element

10-22-2004, 08:49 PM	#12
68w/sbc406 Got Light Emitting Diode? Join Date: Apr 2004 Location: Newberg, OR Posts: 2,485	80s impalas or caprice. __________________ 1968 1/2 ton 2wd lwb 6 lug disc and bags up front. Next c notch and rear bags '02 Chevy Silverado LT ext cab short bed 2WD 5/7 drop on 22's(the family car) 1993 Cherokee work ride/weekend wheeler

10-20-2004, 10:21 PM	#14
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	There was probably warning...he just never checked it. Every time I chainge my oil...and ever truck/van I service at work, I grab the top of the fan, and try to pull it towards the core support. If there is ANY play...it is time for a new one. I also recomend a clutch and a 6 or 7 blade fan...but not a flex fan of any sort. Even the factory ones are junk. When the blades come off they go right through the hood.

10-20-2004, 11:26 PM	#15
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,342	Can someone post a pic of a fan with a clutch on it? Thanks __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

10-21-2004, 09:52 AM	#16
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	Here is a pic of the clutch fan on my engine. Attached Images __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

10-22-2004, 09:52 PM	#17
mdazb Registered User Join Date: Oct 2004 Location: Nor Cal Posts: 75	Anywhere to get a new one? __________________ --------------------------------- 72 C10 SWB 350 Work in progress 98 HD Fatboy 09 HD Heritage Softail 05 Honda Element

10-25-2004, 09:49 PM	#18
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	Be sure you get the one with the thermal clutch in it. Those generally have a small coil on the front of the clutch. They pretty much freewheel unless the air coming through the radiator gets over a certain temperature, then the clutch engages & the fan blows hard. Non-thermal clutches are just a viscous drive, which makes the fan run at slightly less than full speed at all times, whether it's needed or not.

10-25-2004, 10:46 PM	#20
Eddie H. Registered User Join Date: Mar 2001 Location: Paradise TX USA Posts: 1,200	A fan clutch will not only make a lot less noise, but it will also save some fuel. You're wasting 5-10 horsepower turning a non-clutch type fan. __________________ "Negative people always seem to have a problem for every solution"



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10-26-2004, 12:09 AM	#21
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,342	Does the parts stores carry a thermal clutch? Also is there one available for the 4 blade fan I have? __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

10-26-2004, 11:32 AM	#23
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,342	Will do . __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

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