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#1 |
Shake and Bake!
![]() Join Date: Feb 2010
Location: Central Coast, CA
Posts: 609
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Whine/humming sound under light throttle, some advise?
My 1972 C10 with 350/TH350 is making an intermittent whining humming sound when cruising at around 25-30 mph and under very light throttle, like just keeping it running at that speed/rpm.
Its a weird sound, can't quite trace it down yet, almost sounds like the rear end, but it disappears the second you let off the throttle, which doesn't me its not the rear end. But it seems like it would make more noise under more load if it was the RE. Anyone have any ideas before I start ripping into this thing? I am hoping its not a trans pump/torque converter, never slips and shifts good. I am going to be replacing or repairing the PS pump, the whole assembly has some wobble to it at idle, just saw it tonight, almost s#%$ my pants when I saw it. Thanks guys!
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"All tyranny needs to gain a foothold is for people of good conscience to remain silent." Thomas Jefferson "You are remembered for the rules you break." General Douglas MacArthur "Support Our Troops And The NRA" Last edited by Leviticus; 02-15-2010 at 08:55 AM. |
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#2 |
Registered User
Join Date: Sep 2008
Location: Salem Oregon
Posts: 63
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Re: Whine/humming sound under light throttle, some advise?
i have a simliar sound .... i know its not the rear end .... mine almost sound like the tranny ... but i've been driving for 7 years and its always done it .... so it must not be too serious (fingers crossed)
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350/th350 Sportsman2 heads Performer Intake 1406 carb 3.42 Eaton Posi |
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#3 |
Shake and Bake!
![]() Join Date: Feb 2010
Location: Central Coast, CA
Posts: 609
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Re: Whine/humming sound under light throttle, some advise?
Hey guys,
Still have this noise and I can't track it down. It likes to do it while cruising through town and almost coasting, but still just barely on the throttle, give it gas and it seems to go away. On the freeway, it does it a little bit, but when you slow down then give it more gas in third kind of bogging it a little it will make the noise as well. Sounds like you are rubbing a wet finger on the top of a wine glass, type of sound. I am lost, I just serviced the rear diff today and it seemed good inside, no obvious wear. The fluid was a little brown but you could still see through it. It has all new accessories on the engine, and the tranny fluid seems to be at the correct level.
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"All tyranny needs to gain a foothold is for people of good conscience to remain silent." Thomas Jefferson "You are remembered for the rules you break." General Douglas MacArthur "Support Our Troops And The NRA" |
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#4 |
Registered User
Join Date: Dec 2007
Location: Nanaimo B.C.
Posts: 604
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Re: Whine/humming sound under light throttle, some advise?
the way you discribe it sounds to me like it is the rear gears but I have heard that tranny oil pumps can make a whine like this as well.I know thats no help I would check the diff out and make sure the gears don't need a shim adjustment.
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I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!! |
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#5 |
Registered User
Join Date: Feb 2006
Location: Smyrna, Ga
Posts: 1,647
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Re: Whine/humming sound under light throttle, some advise?
from what you are describing, i think i have been chasing the same problem. sounds like a very faint humming when you are barely in the throttle, but not quite decelerating.
i am pretty sure its either the tranny gears or the rear end gears. the gears have alittle play in them, especially older rear ends and trannys. I think its this little bit of play that is casuing the whine. for instance, if you jack up your rear end, hold the drive shaft and/or put the truck in gear, then rock the tires back and forth. Thats the play I am talking about. When your engine is pulling, the gears are meshed all the way one way against one surface of the gear teeth. when you are slowing down, in gear, the gears are meshed the other way on the opposite face of the teeth. when your barely coasting, these gears arent meshing all the way agaisnt each other. so you get a high frequency chatter or vibration from wear on the teeth surface and edges. i could be totally wrong, but those are the only rotating assemblies, that would cause this noise, that havent rebuilt on my truck. |
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#6 |
Registered User
Join Date: May 2009
Location: somewhere, MN
Posts: 110
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Re: Whine/humming sound under light throttle, some advise?
You could try a couple of things:
turn up the radio! (ala click and clack) put glass packs on! lame, I know
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![]() Dad's 1970 Chevy C10 Custom 350, auto, armstrong power windows and doorlocks "My carbon footprint is bigger than yours" ![]() ![]() |
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#7 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: Whine/humming sound under light throttle, some advise?
I am having the same problem as well. I also get a loud whining noise if I put it in first gear, bring it up to about 2500 and then decelerate.
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72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies ![]() ![]() |
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#8 |
Registered User
Join Date: Feb 2007
Location: Cali Central Coast
Posts: 5,191
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Re: Whine/humming sound under light throttle, some advise?
Do you have a two piece drive line?
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'67 SWB Fleetside ZZ4/350/Tremec 5-speed/4link/Scott's IFS - and fun as heck! SOLD ![]() Click here to support the board Philippians 4: 6-7 |
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#9 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: Whine/humming sound under light throttle, some advise?
Me, I don't think I do.
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72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies ![]() ![]() |
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#10 |
Shake and Bake!
![]() Join Date: Feb 2010
Location: Central Coast, CA
Posts: 609
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Re: Whine/humming sound under light throttle, some advise?
Yeah, I have the two piece. I was wondering if maybe it was the Carrier Bearing maybe. I need to find a driveline shop and have them replace it and my u joints cause I am sure they are due.
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"All tyranny needs to gain a foothold is for people of good conscience to remain silent." Thomas Jefferson "You are remembered for the rules you break." General Douglas MacArthur "Support Our Troops And The NRA" |
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#11 | |
Shake and Bake!
![]() Join Date: Feb 2010
Location: Central Coast, CA
Posts: 609
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Re: Whine/humming sound under light throttle, some advise?
Quote:
Thanks
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"All tyranny needs to gain a foothold is for people of good conscience to remain silent." Thomas Jefferson "You are remembered for the rules you break." General Douglas MacArthur "Support Our Troops And The NRA" |
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#12 |
Ridin' Dirty
Join Date: Oct 2009
Location: Ardrossan Alberta Canada
Posts: 2,193
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Re: Whine/humming sound under light throttle, some advise?
I had the exact same symptom on my 02 Suburban with over 300,000 kms on it. I went and got the rear diff rebuilt and the ALL the noise is gone.
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1978 C3500 Crewcab (Project) 1979 C2500 Crewcab (Driver/project) 1988 R2500 Crewcab (Driver) 1988 V3500 Crewcab 1988 R2500 Crewcab (Mint, Ex Fire Dept) 1968 Chev Suburban (4x4 conversion) LINK 1970 Chev C20 Suburban (driver/cruiser)LINK 2005 Impala (Incognito vehicle) 2004 Yukon XL Denali (Kid hauler) 1947 Case tractor Facebook Page(1000's of pictures of GM cars and trucks organized into albums) YouTube Channel |
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#13 |
Registered User
Join Date: Jan 2008
Location: Tejas
Posts: 691
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Re: Whine/humming sound under light throttle, some advise?
my diff does that, maybe just the way the gears mesh under that amount of load. I know first gear in my th350 is loud
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'72 cheyenne super step, '05 long bed gmc |
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#14 |
Registered User
Join Date: Feb 2008
Location: Madison, WI
Posts: 357
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Re: Whine/humming sound under light throttle, some advise?
Carrier Bearing on all of these trucks I'd guess.
Check it before you tear into the rear end.. like I did. lol
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1972 Long Bed Cheyenne Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=285282 Waste my bandwidth and listen to some great tunes >> http://www.radioxenu.com (Live Shows with yours truly every Friday) |
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#15 |
Shake and Bake!
![]() Join Date: Feb 2010
Location: Central Coast, CA
Posts: 609
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Re: Whine/humming sound under light throttle, some advise?
Did you have this same sound when your carrier was going out?
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"All tyranny needs to gain a foothold is for people of good conscience to remain silent." Thomas Jefferson "You are remembered for the rules you break." General Douglas MacArthur "Support Our Troops And The NRA" |
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#16 |
Registered User
Join Date: Feb 2006
Location: Smyrna, Ga
Posts: 1,647
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Re: Whine/humming sound under light throttle, some advise?
one piece drive shaft on mine.
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#17 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,216
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Re: Whine/humming sound under light throttle, some advise?
Sounds like rear end noise to me. Take hold of the pinion flange & see if there is any up & down play in it. Slack when you turn it is normal but it should not have any brg. loosness. Pull the cover. There should not be any side to side play in the carrier.
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#18 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: Whine/humming sound under light throttle, some advise?
The noise your talking about in first gear, is it only when you decelerate. My TH350 dose the too, almost sounds like a blower.
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72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies ![]() ![]() |
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#19 |
Registered User
Join Date: Sep 2012
Location: Lawton Oklahoma
Posts: 308
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Re: Whine/humming sound under light throttle, some advise?
Mine is doing this too!
I have it in the air and I am turning the drive shaft by hand. The whining is coming from the tail shaft area. I am going to pull the speedo cable and then the speedo gear! Then recheck if stays I will pull front u joint to ensure it is not radiating from the dif. Then turn the yoke by hand see if it stays.... Posted via Mobile Device
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#20 |
Proprietor of Dale's Corner
![]() Join Date: Nov 2012
Location: Vacaville , CA
Posts: 16,102
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Re: Whine/humming sound under light throttle, some advise?
I've heard stories from old GM techs that 67-72 was famous for the hood hinge springs humming under differing conds on different trucks. They said it drove them crazy until service bulletin came out on it. Stuff the springs with a piece of foam rubber and see if this helps (GMs tech suggestion).
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"Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man |
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#21 |
Cluster King
![]() Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,263
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Re: Whine/humming sound under light throttle, some advise?
First, what gear is the trans in at 25 - 30 mph? Has it shifted in to 3rd gear yet? Try and drive it in low gear at the same speed and see if it makes the same noise. If it makes the same noise at the same speed regardless of the gear, then I would not suspect the trans is the problem since you are changing the rpm's.
How many miles would you say the rear diff has on it? From what you describe the first thing I thought was the ring gear is wearing out of spec on the drive side. When the ring and pinion wear, the back lash gets looser and gap between the pinion and the ring gear increases. It also puts the relationship between where the ring and pinion mesh in a different spot. That will cause a noise under a slight load. Do you know how to check the wear pattern on a ring gear? If you get the cover off and look at it, the pattern should be fairly close to the center of the ring gear tooth on both sides. They make a compound for checking gear patterns that you could by from a transmission parts supplier. This can get rather involved but there is hope. If you can get your hands on a good GM service manual, all of this is explained in detail and how to correct it. Keep us posted. |
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#22 |
Registered User
Join Date: Oct 2012
Location: Lebanon Ohio
Posts: 187
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Re: Whine/humming sound under light throttle, some advise?
Mine does this as well. Found out from a retired mechanic that when the bushings in TH350 wear down , the gears become a little loose and creates this sound. He said that it doesnt really hurt anything and not to worry about it. He said only way to get rid of it was to rebuild... $$$$$ . But he also told me if I had it rebuilt to tell them about the whine to make sure they shim it correctly.
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1971 Chevrolet C10 Inflation Fighter ![]() 1994 C3500 Crew Cab Dually 454
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#23 |
Registered User
Join Date: Sep 2012
Location: San Antonio, TX
Posts: 1,026
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Re: Whine/humming sound under light throttle, some advise?
I have this same sound as well. I was thinking it was the trans as well. As long as it doesn't hurt anything i will leave as is
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Jeff 1972 Cheyenne Super SWB 350, Auto, Bucket Seats w/Console, Tach, Factory A/C, P/S ,P/B, Tilt 1998 Chevy 1500 Ext Cab 5.7, Pewter w/blue interior |
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#24 |
Registered User
![]() Join Date: Mar 2012
Location: Okanagan Valley, BC, Canada
Posts: 1,237
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Re: Whine/humming sound under light throttle, some advise?
My 1970 GMC does the same thing. Its constant with different engine RPM and does it under load or coasting, but louder under load. I am assuming its the rear end. Im going to change the fluid and hope it goes away... although it does honestly sound kinda cool like a quiet blower under the hood.
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#teamlongbed "I refuse to go disc brakes. I actually love drum brakes. It makes for an adventure." - 50bomb 1978 Chevy shop truck - static 6/8" 1970 GMC 1500 - Accuair eLevel Resto-mod http://67-72chevytrucks.com/vboard/s...d.php?t=537497 |
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#25 |
Registered User
Join Date: Aug 2013
Location: Fort st John B.C. Canada
Posts: 8
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Re: Whine/humming sound under light throttle, some advise?
its your diff, mine does the same thing under slight load, just the way the crown and pinion are meshing inside the case. you can try to shim the pinion however it will only get marginally better, but will never go away completley
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