Fan Belt Squealing...
Thread Starter
Racer
Joined: Nov 2007
Posts: 320
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From: Upstate New York
Fan Belt Squealing...
I'm getting down to the last few bugs!
Under acceleration you can hear the fan belt squealing and at 2500 it continues to make noise.
It's a 68 427 390 and I'm using the original belt system whereby the WP and PS pulley is driven by the crank pulley and the PS pulley drives the alternator.
I was told to use a non clutch type fan for better cooling so I'm using a 6 blade fan with no clutch.
I've also tried a different belt on the alternator but not the crank, PS, WP belt although it's new.
It's not a very good system to depend on 1 belt to essentially drive everything but if it was done that way originally it should work and I do want to keep it original.
The fan is not original though and could it be the clutch fan slippage would allow the pulleys not to squeal?
Under acceleration you can hear the fan belt squealing and at 2500 it continues to make noise.
It's a 68 427 390 and I'm using the original belt system whereby the WP and PS pulley is driven by the crank pulley and the PS pulley drives the alternator.
I was told to use a non clutch type fan for better cooling so I'm using a 6 blade fan with no clutch.
I've also tried a different belt on the alternator but not the crank, PS, WP belt although it's new.
It's not a very good system to depend on 1 belt to essentially drive everything but if it was done that way originally it should work and I do want to keep it original.
The fan is not original though and could it be the clutch fan slippage would allow the pulleys not to squeal?
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
The V-grooves of the pulleys are probably not in perfect shape. The squealing is a symptom of slippage. At higher RPM, the belt is not getting good traction in the groove, and it's slipping creating the noise. You might try a thicker, as in wider, belt than stock, or maybe find a new set of pulleys.
Race Director
Joined: Dec 1999
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From: Sierra Foothills CA
I had the same pulley set up on my Vette & the same problem. Doing the above procedure helped but not for long & eventually even that did no good. The pulleys get worn & glazed after many years of service. Putting something slippery on the belts will eliminate the squeal for awhile but if you're at all marginal with your cooling system (not unusual for a bigblock of our vintage) you don't want your belts slipping. I got tired of the squeal & bought a set of March pulleys- problem solved. You could shop carefully & spend less money on a set of stock replacement pulleys too. Good luck.
Race Director
Joined: Sep 2001
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From: Wellington, FL
St. Jude Donor '11 thru '25
I'd replace the belt as your old one is now probably burnt. When you do so, buy a premium belt as they are steel reinforced. The cheaper ones are not and will stretch and start squealing. 
Drifting
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From: Tomahawk WI
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From: San Diego - Deep Within The State of CONFUSION!
Whoever told you to NOT use a fan clutch was an inept wannabe mechanic, in no position to give advice.
That being said, the solutions above will fix the squealing problem but I highly advise you to replace the clutch on the fan if it is in good working order.
That being said, the solutions above will fix the squealing problem but I highly advise you to replace the clutch on the fan if it is in good working order.
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Drifting
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St. Jude Donor '07
Not sure what other accessories you are running but on some of the original set ups there was a belt from the WP to the crank only. If you have the empty groves there try finding that belt and it will help. My small block uses a belt 36 inches long. Not sure if the BB is the same. Cured the squealing on mine. 
Thread Starter
Racer
Joined: Nov 2007
Posts: 320
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From: Upstate New York
Thanks for the help!
I did sand all the grooves and the pulleys are new except for the PS.
DB, Jud, I will try a wider premium belt for the crank pulley and see what happens.
Les, I do want to keep it stock even though it's not the best set up otherwise I'd do what you did.
San Diego, Paul, I still have the old clutch set up and if all the above doesn't fix the squeal I'll try that.
I did sand all the grooves and the pulleys are new except for the PS.
DB, Jud, I will try a wider premium belt for the crank pulley and see what happens.
Les, I do want to keep it stock even though it's not the best set up otherwise I'd do what you did.
San Diego, Paul, I still have the old clutch set up and if all the above doesn't fix the squeal I'll try that.
Thread Starter
Racer
Joined: Nov 2007
Posts: 320
Likes: 0
From: Upstate New York
Not sure what other accessories you are running but on some of the original set ups there was a belt from the WP to the crank only. If you have the empty groves there try finding that belt and it will help. My small block uses a belt 36 inches long. Not sure if the BB is the same. Cured the squealing on mine.
Race Director
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From: Wellington, FL
St. Jude Donor '11 thru '25
Team Owner
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From: Crossville TN
If memory serves me correctly (and it frequently does not), the damper to water pump pulley belt does not have any damper. It just gets installed & tightened when the W/P pulley is installed. If you have those extra grooves in those pulleys, just go to NAPA and get a good quality [and correct] belt. That should keep the other one from slipping. Oh, and since it has been slipping and is likely glazed, replace it, too.
Team Owner
Joined: Jan 2006
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From: Crossville TN
Let's try that again....
If memory serves me correctly (and it frequently does not), the damper to water pump pulley belt does not have any idler. It [the belt] just gets installed & tightened when the W/P pulley is installed. If you have those extra grooves in those pulleys, just go to NAPA and get a good quality [and correct] belt. That should keep the other one from slipping. Oh, and since it has been slipping and is likely glazed, replace it, too.
If memory serves me correctly (and it frequently does not), the damper to water pump pulley belt does not have any idler. It [the belt] just gets installed & tightened when the W/P pulley is installed. If you have those extra grooves in those pulleys, just go to NAPA and get a good quality [and correct] belt. That should keep the other one from slipping. Oh, and since it has been slipping and is likely glazed, replace it, too.
Intermediate
Joined: Mar 2006
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From: Dripping Springs TX
Thread Starter
Racer
Joined: Nov 2007
Posts: 320
Likes: 0
From: Upstate New York
Let's try that again....
If memory serves me correctly (and it frequently does not), the damper to water pump pulley belt does not have any idler. It [the belt] just gets installed & tightened when the W/P pulley is installed. If you have those extra grooves in those pulleys, just go to NAPA and get a good quality [and correct] belt. That should keep the other one from slipping. Oh, and since it has been slipping and is likely glazed, replace it, too.
If memory serves me correctly (and it frequently does not), the damper to water pump pulley belt does not have any idler. It [the belt] just gets installed & tightened when the W/P pulley is installed. If you have those extra grooves in those pulleys, just go to NAPA and get a good quality [and correct] belt. That should keep the other one from slipping. Oh, and since it has been slipping and is likely glazed, replace it, too.
Team Owner
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From: Columbia Missouri
Racer
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From: Roselle IL
Good luck
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I am running a stock clutch fan on my 68 427/390 with no overheating problems. Most belt squealing is due to the belt not being properly tensioned.