Whining

S

stephen thomas

New member
May 29, 2014
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Hi Folks,

It's been a while since I've driven the GMC and I think there's a new
noise. It sounds like a whine that bearings or gears might make. The pitch
goes up and down with the speed of the vehicle (not the rpm of the motor).
I start to notice it at around 25 mph and it gets a bit louder on the
highway. It goes away completely when I'm coasting. My friends think I'm
being paranoid. They can't seem to hear it.

Any idea what could be making a noise like this? Do I need to worry or is a
little bit of whining normal? Any advice would be great.

Thanks,
Steve
78 Eleganza
Santa Cruz, CA
 
Sounds like something between the torque converter and the tires. Try hard
pull, deceleration, and neutral throttle and compare sounds. Take someone
with very acute hearing along with you during test drive. Check for high
temperatures on the final drive, inner and outer CV joints, and hubs,
knuckles, brakes, as well as rear hubs. Keep checking. These coaches are 40
years old. Crap happens.
Jim Hupy

> Hi Folks,
>
> It's been a while since I've driven the GMC and I think there's a new
> noise. It sounds like a whine that bearings or gears might make. The pitch
> goes up and down with the speed of the vehicle (not the rpm of the motor).
> I start to notice it at around 25 mph and it gets a bit louder on the
> highway. It goes away completely when I'm coasting. My friends think I'm
> being paranoid. They can't seem to hear it.
>
> Any idea what could be making a noise like this? Do I need to worry or is a
> little bit of whining normal? Any advice would be great.
>
> Thanks,
> Steve
> 78 Eleganza
> Santa Cruz, CA
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
It could be a gear whine in the final Drive. The fact that it continues to make a steadily increasing pitch noise and goes away on coast points in
that direction.

--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
The final drive was my first thought. I topped it off with about 5 oz of
oil, but I don't think that made any difference.

While I was under there, I found that the CV boot had a hole in it and
there was grease all over the place. The joint only has about 3000 miles on
it, but I don't know when it started leaking. I'd be surprised if this was
making the noise but, it wouldn't hurt to replace it, I guess.

I didn't think to check for heat. I'll definitely be doing that this
weekend.

Seems like a great excuse for a drive up the coast!

Thanks guys,

Steve
78 Eleganza
Santa Cruz, CA

> It could be a gear whine in the final Drive. The fact that it continues
> to make a steadily increasing pitch noise and goes away on coast points in
> that direction.
>
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
> Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
> Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
If it is a final drive don't ignore it like I did, mine had whined it since the day I bought it, thought it was normal. Guess it was slack in FD
pinion bearing. It went out after 4 years and took out the output shaft of the tranny at the same time. When that happens like mine on a hill you sure
wish you had fixed the parking brake. That's why I always carry wheel chocks in the refrigerator access door. Just from my experience. BTW I do have
parking brakes now.
Skip Hartline
 
> The final drive was my first thought. I topped it off with about 5 oz of oil, but I don't think that made any difference.
>
> While I was under there, I found that the CV boot had a hole in it and there was grease all over the place. The joint only has about 3000 miles
> on
> it, but I don't know when it started leaking. I'd be surprised if this was making the noise but, it wouldn't hurt to replace it, I guess.
>
> I didn't think to check for heat. I'll definitely be doing that this weekend.
>
> Seems like a great excuse for a drive up the coast!
>
> Thanks guys,
>
> Steve

Steve,

Some other information to gather:
Does it make this same sound in all gears? - You may have to hold it down to check.
Does it change at all with load? - There may be a short change when you back off the throttle.

Good Luck - have a nice, but boring drive.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
I would do about 35 and see if pitch is same in D and S. If so, you can rule out engine and most likely MOST of the trans except output shaft
section. I would then in S get lightly on and off the gas as if driving a manual and see if loading, unloadind, decel loading follows what would be
final drive gear or bearing noise. I would drain and catch final drive fluid as a clue to metal in fluid. Easy test. Good catch on boot but that is
not a whine candidate.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
More'n half the time that's coming from the differential - excuse me, final drive. Clues are it varies with road speed, not engine speed, and it
changes with load. I defer to wiser minds as to what to do about it... I've had vehicles which did this their lifetime, and one old Dodge which
whined for about a week and then spit the diff onto the pavement, oil, ring gear, and all.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
> Hi Folks,
>
> It's been a while since I've driven the GMC and I think there's a new
> noise. It sounds like a whine that bearings or gears might make. The pitch
> goes up and down with the speed of the vehicle (not the rpm of the motor).
> I start to notice it at around 25 mph and it gets a bit louder on the
> highway. It goes away completely when I'm coasting. My friends think I'm
> being paranoid. They can't seem to hear it.

I would think about the alternator. My coach whines at 2300 RPMs and up. Park. Put it in park and run the engine up and down. If you hear it, then do
the shade tree trick. Get a broomstick, put it to your ear and touch the alternator, power steering, and water pump. Don't get it in a belt or fan.

Why haven't I changed the alternator? Because after a string of 5 that failed, this one charges the battery.
--
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
 
One other thought, since it's road speed variable, try turning under load and see if it changes as you load one front wheel and then the other.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
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