whining noise when accelerating - from where? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**cdub2010** · 05-31-2017, 02:26 PM

I have finally got my truck drivable after a year and a half of fixing a ton of stuff. Now im chasing down a whining noise when accelerating from 20 to 60 mph. The noise seems to get louder the faster I go. It goes away when I let off the gas. I havent gone over 60 yet, still in shakedown mode.

Background info is the truck is a 71 LWB 2wd 350/350 with 3.73 open diff. It has had a serpentine setup from a 90 chevy with new alternator, fan, fan clutch and waterpump. The drivetrain has new flexplate, rebuilt th350 with new converter, re-balanced drive shaft with new carrier bearing and new u-joints, the rear axle fluid changed. Rear gears were a bit rusty from sitting for so long, looks like a few teeth are lightly pitted but no chips or bigger damage.

any ideas?

**Stocker** · 05-31-2017, 02:51 PM

Just a guess.... being speed-related (20 to 60 mph) and only when accelerating, it may be the differential.

Marine-58 · 05-31-2017, 02:57 PM

More than a few years ago I had a similar issue on an inboard boat engine. Turned out to be a vacuum leak between the intake and head. Tightened down on the bolts and it got better but had to replace the intake gasket to make it go away.

I was only 14 and learned how to properly install an intake from that experience...

demian5 · 05-31-2017, 03:29 PM

Quote:

Originally Posted by Stocker

Just a guess.... being speed-related (20 to 60 mph) and only when accelerating, it may be the differential.

I 2nd that.

Wrenchbender Ret · 05-31-2017, 03:30 PM

My vote is for the rear end. Check for any looseness in the pinion brgs. If that's OK pull the cover back off & check for any side to side motion in the carrier. If that's OK check the tooth contact pattern in the ring & pinion.

**truckster** · 05-31-2017, 03:41 PM

Quote:

Originally Posted by Wrenchbender Ret

My vote is for the rear end. Check for any looseness in the pinion brgs. If that's OK pull the cover back off & check for any side to side motion in the carrier. If that's OK check the tooth contact pattern in the ring & pinion.

My first thought was the pinion bearing. Most likely culprit, in my opinion.

Shinysideup · 05-31-2017, 04:26 PM

Did you replace the pinion seal when you were into the differential?

nevada · 05-31-2017, 04:30 PM

Its the Rear Diff.

mine does the same thing, whines louder as I go faster, take foot off gas, sound goes away....my 72 C20 with 4.11 rear gear, piñion is worn. trucked lugged a heavy 10 ft Alaskan camper in back its whole life, just had the motor worked on.. new cam and lifters installed this week and motor sounds smooth. still have the rear diff noise. won't hurt anything if not being used to work hard towing or hauling (camper is removed now)...I'll let mine whine for another year until I can afford to have a 700r tranny installed and will have the worn 4.11 pulled and install a 3.73 at that time.

weq92f · 05-31-2017, 05:32 PM

Sounds like gear whine.

-klb

**cdub2010** · 05-31-2017, 10:36 PM

Quote:

Originally Posted by Shinysideup

Did you replace the pinion seal when you were into the differential?

no, there were no leaks from the pinion, just changed the gear oil. I cant move the pinion yoke in or out with the driveshaft removed.
Its quite loud around 45, guess ill get on the radio install.

cypressbog · 06-01-2017, 01:19 PM

I had the same thing. In my case it was the wife bearing. Bought her some chocolates and flowers and the whining went away for a while,

05-31-2017, 02:26 PM	#1
cdub2010 Senior Member Join Date: Apr 2014 Location: detroit mi Posts: 209	whining noise when accelerating - from where? I have finally got my truck drivable after a year and a half of fixing a ton of stuff. Now im chasing down a whining noise when accelerating from 20 to 60 mph. The noise seems to get louder the faster I go. It goes away when I let off the gas. I havent gone over 60 yet, still in shakedown mode. Background info is the truck is a 71 LWB 2wd 350/350 with 3.73 open diff. It has had a serpentine setup from a 90 chevy with new alternator, fan, fan clutch and waterpump. The drivetrain has new flexplate, rebuilt th350 with new converter, re-balanced drive shaft with new carrier bearing and new u-joints, the rear axle fluid changed. Rear gears were a bit rusty from sitting for so long, looks like a few teeth are lightly pitted but no chips or bigger damage. any ideas?

05-31-2017, 02:51 PM	#2
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,688	Re: whining noise when accelerating - from where? Just a guess.... being speed-related (20 to 60 mph) and only when accelerating, it may be the differential. __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

05-31-2017, 02:57 PM	#3
Marine-58 Registered User Join Date: May 2017 Location: Parker, CO Posts: 130	Re: whining noise when accelerating - from where? More than a few years ago I had a similar issue on an inboard boat engine. Turned out to be a vacuum leak between the intake and head. Tightened down on the bolts and it got better but had to replace the intake gasket to make it go away. I was only 14 and learned how to properly install an intake from that experience...

05-31-2017, 03:30 PM	#5
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,228	Re: whining noise when accelerating - from where? My vote is for the rear end. Check for any looseness in the pinion brgs. If that's OK pull the cover back off & check for any side to side motion in the carrier. If that's OK check the tooth contact pattern in the ring & pinion.

05-31-2017, 04:30 PM	#8
nevada Registered User Join Date: Feb 2017 Location: reno nv Posts: 64	Re: whining noise when accelerating - from where? Its the Rear Diff. mine does the same thing, whines louder as I go faster, take foot off gas, sound goes away....my 72 C20 with 4.11 rear gear, piñion is worn. trucked lugged a heavy 10 ft Alaskan camper in back its whole life, just had the motor worked on.. new cam and lifters installed this week and motor sounds smooth. still have the rear diff noise. won't hurt anything if not being used to work hard towing or hauling (camper is removed now)...I'll let mine whine for another year until I can afford to have a 700r tranny installed and will have the worn 4.11 pulled and install a 3.73 at that time.

05-31-2017, 05:32 PM	#9
weq92f Registered User Join Date: Oct 2016 Location: Dallas Texas Posts: 3,151	Re: whining noise when accelerating - from where? Sounds like gear whine. -klb __________________ 67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold

06-01-2017, 01:19 PM	#11
cypressbog Go Pack Go! Join Date: Nov 2005 Location: Green Bay Posts: 2,669	Re: whining noise when accelerating - from where? I had the same thing. In my case it was the wife bearing. Bought her some chocolates and flowers and the whining went away for a while,



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