Loud squeal on startup and sometimes while driving - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kcackler · 05-05-2009, 05:21 PM

Working on my little brother's 86 GMC sierra 3/4 ton truck and want to fix this last annoying issue before he moves up here.

When you start the truck up, 99% of the time, a VERY LOUD squeal happens. And it happens usually until the truck is warmed up. Even while you're driving, though, it will occasionally start back up.

The belts are new and tensioned properly. I've read that it could be the fan clutch. Is there any test I can do to confirm that it is or isn't? Just want to make sure before dropping 50 bucks on a new one.

Also, is the fan clutch something that can be easily replaced in under an hour or so?

JohnC · 05-05-2009, 05:47 PM

You may do a search on here. There was a thread talking about this a month or so ago. I'm not real familiar with the fan clutches so I can't give you much help there.

AceX · 05-06-2009, 02:40 AM

Fan clutch is super easy to replace. I could probably do it in 20 minutes if I really go at it.

You can always grab a spacer from the local parts store for cheap, and use it to space the fan away form the pulley like the clutch would. If it still makes the noise, you know to look elsewhere.

Also, does the truck have A/C? The A/C belt is a PITA to tension properly, and it may also be a bad A/C compressor clutch.

heavychevy79 · 05-06-2009, 03:25 AM

The belt is slipping on the alternator pulley, then goes away when the battery
voltage comes back up.
Take some sandpaper to the pulley and rough it up, and change the belt too if it looks badly glazed.

Lated · 05-06-2009, 03:54 AM

Quote:

Originally Posted by heavychevy79

The belt is slipping on the alternator pulley, then goes away when the battery
voltage comes back up.
Take some sandpaper to the pulley and rough it up, and change the belt too if it looks badly glazed.

Either that or the alternator bearing is going out. Mine made the same nasty noises when the bearing was going.

truckincurt · 05-06-2009, 09:01 AM

also might be a power steering pump have you checked fluid level latley?

73chevyman · 05-07-2009, 07:30 PM

most of the time a squeal is either altinator, and or aa locked up device such as altinator, ac compressor, and power steering. most of the time if you do not see any smoke it's a loose belt make sure your belts are tighten or not stretched if so replace good luck.

79gmcc15 · 05-07-2009, 07:56 PM

if it is anything like the video posted then yes it is the alternator. I replaced mine yesterday.

YouTube - Truck Video 4

88 Dippy · 05-07-2009, 10:28 PM

i get that same noise but only when i out it in reverse. and some times wile going down the road. it is varry odd

05-05-2009, 05:21 PM	#1
kcackler Registered User Join Date: Feb 2009 Location: Russellville, AR Posts: 164	Loud squeal on startup and sometimes while driving Working on my little brother's 86 GMC sierra 3/4 ton truck and want to fix this last annoying issue before he moves up here. When you start the truck up, 99% of the time, a VERY LOUD squeal happens. And it happens usually until the truck is warmed up. Even while you're driving, though, it will occasionally start back up. The belts are new and tensioned properly. I've read that it could be the fan clutch. Is there any test I can do to confirm that it is or isn't? Just want to make sure before dropping 50 bucks on a new one. Also, is the fan clutch something that can be easily replaced in under an hour or so? __________________ Blue - 77 Chevy Scottsdale

05-05-2009, 05:47 PM	#2
JohnC Registered User Join Date: Feb 2009 Location: Oklahoma Posts: 7,461	Re: Loud squeal on startup and sometimes while driving You may do a search on here. There was a thread talking about this a month or so ago. I'm not real familiar with the fan clutches so I can't give you much help there.

05-06-2009, 02:40 AM	#3
AceX >130dB Moderator Join Date: Aug 2006 Location: Sacramento, CA Posts: 2,130	Re: Loud squeal on startup and sometimes while driving Fan clutch is super easy to replace. I could probably do it in 20 minutes if I really go at it. You can always grab a spacer from the local parts store for cheap, and use it to space the fan away form the pulley like the clutch would. If it still makes the noise, you know to look elsewhere. Also, does the truck have A/C? The A/C belt is a PITA to tension properly, and it may also be a bad A/C compressor clutch. __________________ Living Life @ 130dB LED Tail Light Conversion; How-to Friend. Father. Brother. RIP El Jay ------------------------------------------------------------------------------------------------------------------------- CLICK HERE and for less than $0.07 a day, you too can help support and build a better forum.

05-06-2009, 03:25 AM	#4
heavychevy79 Cheyenne Super Join Date: Nov 2008 Location: Dallas Texas Posts: 545	Re: Loud squeal on startup and sometimes while driving The belt is slipping on the alternator pulley, then goes away when the battery voltage comes back up. Take some sandpaper to the pulley and rough it up, and change the belt too if it looks badly glazed.

05-06-2009, 09:01 AM	#6
truckincurt Registered User Join Date: Mar 2008 Location: Lockport, NY Posts: 106	Re: Loud squeal on startup and sometimes while driving also might be a power steering pump have you checked fluid level latley?

05-07-2009, 07:30 PM	#7
73chevyman Registered User Join Date: Nov 2008 Location: Lusby, MD Posts: 563	Re: Loud squeal on startup and sometimes while driving most of the time a squeal is either altinator, and or aa locked up device such as altinator, ac compressor, and power steering. most of the time if you do not see any smoke it's a loose belt make sure your belts are tighten or not stretched if so replace good luck. __________________ http://67-72chevytrucks.com/vboard/group.php?groupid=37 73 C10 Fleetside If it ain't a Chevy it's foreign http://hotridesmag.com/

05-07-2009, 10:28 PM	#9
88 Dippy Registered User Join Date: Feb 2009 Location: mt. Pleasant, MI Posts: 246	Re: Loud squeal on startup and sometimes while driving i get that same noise but only when i out it in reverse. and some times wile going down the road. it is varry odd __________________ 1974 chevy Cheyenne C10 "The Mutt":4x4 convertion, NP208, 700-R4, stock 350, edelbrock Torker intake, edelbrock 600 CFM carb, duels 2001 Pontiac Grand Prix GT: 3.8L supercharged, 9.2:1 comprestion, ZZP XP cam, home made intake, 2 1/2" exhuast, 10psi of boost



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