Mystery noise

R

ray elliott

New member
Feb 8, 2000
34
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Hey GMCers:
I've had two good shops test drive my coach trying to figure out what
the whine noise is. Both tell me it's the differential. That's what I
thought too. My GMC has 65k miles. Are these final drive units known
to have problems? Anybody here gone through this? Would like to hear
your advice on what to do now...
Ray Elliott
Grants Pass, OR
'77PB
 
Ray,
They all have a little noise in them. When is the last time that you
changed the fluid in the final drive? You should change the fluid about
every 12K miles as cheap insurance. I would pull the cover and drain
the fluid into a pan and take a look at what's on the bottom of the pan
after it sets for a few minutes. You will always find some metal in the
bottom of the pan. What matters is if there is a large amount there.
65K miles is nothing on these final drives, I upgraded to 3.55 ratio
final drive at 100K and the original final was in great shape. Some
GMC'ers have over 200K or more on their original drives, it just a
matter of taking care of it and changing the oil.

- -
J.R. Wright
GMC GreatLakers
77 Eleganza II
Michigan

>
> Hey GMCers:
> I've had two good shops test drive my coach trying to figure out what
> the whine noise is. Both tell me it's the differential. That's what I
> thought too. My GMC has 65k miles. Are these final drive units known
> to have problems? Anybody here gone through this? Would like to hear
> your advice on what to do now...
> Ray Elliott
> Grants Pass, OR
> '77PB

- -
 
This final drive noise is definitely new. It wasn't there 200 miles
ago. I had the final drive serviced when I got the coach as a part of
some routine maintenance, and that was only 1,000 miles ago. I changed
it again a few days ago and the noise is still there. The pan drippings
were unremarkable. I'm taking another trip starting tomorrow so we'll
see how it goes. Thanks to those who responded to my query.
Ray

Ray,
They all have a little noise in them. When is the last time that you
changed the fluid in the final drive? You should change the fluid about

every 12K miles as cheap insurance. I would pull the cover and drain
the fluid into a pan and take a look at what's on the bottom of the pan
after it sets for a few minutes. You will always find some metal in the

bottom of the pan. What matters is if there is a large amount there.
65K miles is nothing on these final drives, I upgraded to 3.55 ratio
final drive at 100K and the original final was in great shape. Some
GMC'ers have over 200K or more on their original drives, it just a
matter of taking care of it and changing the oil.

- - -
J.R. Wright
GMC GreatLakers
77 Eleganza II
Michigan

>
> Hey GMCers:
> I've had two good shops test drive my coach trying to figure out what
> the whine noise is. Both tell me it's the differential. That's what
I
> thought too. My GMC has 65k miles. Are these final drive units known

> to have problems? Anybody here gone through this? Would like to hear

> your advice on what to do now...
> Ray Elliott
> Grants Pass, OR
> '77PB
 
> This final drive noise is definitely new. It wasn't there 200 miles
> ago. I had the final drive serviced when I got the coach as a part
> of
> some routine maintenance, and that was only 1,000 miles ago. I
> changed
> it again a few days ago and the noise is still there. The pan
> drippings
> were unremarkable. I'm taking another trip starting tomorrow so
> we'll
> see how it goes. Thanks to those who responded to my query.
> Ray
>
This may have been covered by others but since the coach is new to you,
do you suppose the P.O. installed a 346 final drive? The early ones
were/are noisy and it is possible you have only just noticed the noise?

David Lee Greenberg
The GMC Motorhome Registry
Dedicated To The Preservation of the Classic GMC Motorhome
http://www.GMCss.com/Registry.htm
http://www.Buskirk-RushRV/GMC-Registry/online-registry.htm
 
Dave,

You wrote "do you suppose the P.O. installed a 346 final drive? The early
ones were/are noisy and it is possible you have only just noticed the
noise?"
My coach has a 3.46 final drive, installed in 01/98 - does that make it an
"early" one? I hear a "growling" noise, even under a light load, goes away
when I take my foot off the accelerator - it doesn't sound like the typical
final drive whine, but you got me thinking now....

Peter
77 Eleganza II
Colorado

- ----- Original Message -----
From:
To:
Sent: Friday, July 14, 2000 4:13 PM
Subject: Re: GMC: Mystery noise

> > This final drive noise is definitely new. It wasn't there 200 miles
> > ago. I had the final drive serviced when I got the coach as a part
> > of
> > some routine maintenance, and that was only 1,000 miles ago. I
> > changed
> > it again a few days ago and the noise is still there. The pan
> > drippings
> > were unremarkable. I'm taking another trip starting tomorrow so
> > we'll
> > see how it goes. Thanks to those who responded to my query.
> > Ray
> >
> This may have been covered by others but since the coach is new to you,
> do you suppose the P.O. installed a 346 final drive? The early ones
> were/are noisy and it is possible you have only just noticed the noise?
>
> David Lee Greenberg
> The GMC Motorhome Registry
> Dedicated To The Preservation of the Classic GMC Motorhome
> http://www.GMCss.com/Registry.htm
> http://www.Buskirk-RushRV/GMC-Registry/online-registry.htm
>
 
> Dave,
>
> You wrote "do you suppose the P.O. installed a 346 final drive? The
> early ones were/are noisy and it is possible you have only just noticed

> the noise?"
> My coach has a 3.46 final drive, installed in 01/98 - does that make
> it an "early" one? I hear a "growling" noise, even under a light load,
> goes away when I take my foot off the accelerator - it doesn't sound
like the
> typical final drive whine, but you got me thinking now....
>
> Peter
> 77 Eleganza II
> Colorado
>
>
It was surely was made prior to then so it could be an early final drive
unit. One of our members couldn't stand the noise from his and had it
removed soon after installation and the next unit was also too noisy so
that was uninstalled and replaced by a 366 ratio unit.

I know both Jim Bounds and Alex Sirum sent 346's back to Peck for this
reason. others who had them installed didn't notice any unusually loud
whine, etc., but one owner I noticed wearing two hearing aids!

David Lee Greenberg
The GMC Motorhome Registry
Dedicated To The Preservation of the Classic GMC Motorhome
http://www.GMCss.com/Registry.htm
http://www.Buskirk-RushRV/GMC-Registry/online-registry.htm
 
- ----- Original Message -----
From:
To:
Sent: Sunday, July 16, 2000 9:31 AM
Subject: GMC: Mystery noise

> It was surely was made prior to then so it could be an early final drive
> unit. One of our members couldn't stand the noise from his and had it
> removed soon after installation and the next unit was also too noisy so
> that was uninstalled and replaced by a 366 ratio unit.
>
> I know both Jim Bounds and Alex Sirum sent 346's back to Peck for this
> reason. others who had them installed didn't notice any unusually loud
> whine, etc., but one owner I noticed wearing two hearing aids!
>
>
> David Lee Greenberg
> The GMC Motorhome Registry
> Dedicated To The Preservation of the Classic GMC Motorhome
> http://www.GMCss.com/Registry.htm
> http://www.Buskirk-RushRV/GMC-Registry/online-registry.htm

Thanks, Dave.
You're right, who knows how long the thing sat at Osburn's in NM! The noise
isn't really annoying, I just worry about stuff like that.

Peter
77 Eleganza II
Colorado
 
- ----- Original Message -----
From: Peter Brandt
To:
Sent: Tuesday, July 18, 2000 2:14 AM
Subject: Re: GMC: Mystery noise

The noise
> isn't really annoying, I just worry about stuff like that.
>
> Peter
> 77 Eleganza II
> Colorado
>
>

Worrying about the noises, and finding out what is causing them is a good
habit! In the 25 years we have had our coach we have made the mistake of
ignoring some noises and were usually rewarded with a good swift kick in the
posterior. When your GMC talks, listen!

Tony Bad
 
> Worrying about the noises, and finding out what is causing them is a good
> habit! In the 25 years we have had our coach we have made the mistake of
> ignoring some noises and were usually rewarded with a good swift kick in
the
> posterior. When your GMC talks, listen!
>
> Tony Bad

Thanks, Tony!
I've been accused (by my wife) of worrying too much about strange noises!
Peter
 
Well, for further evidence....

Ignored wheel noise early on (when we knew little about bearing issues) and
had left front wheel FALL OFF at 60 mph

Ignored fan noise...had clutch seize on side of route 95 in Brunswick GA

Ignored squeak from front of engine when in hurry preparing for trip....had
water pump go bad again on side of 95 in Virginia

Brake noises ignored...seized front brake caliper, which actually turned out
to be a bad brake hose. Fell apart internally, preventing release of brake
pressure.

Need I go on......

I don't want to suggest paranoia is needed, but paying attention is never a
bad idea.

Please learn from my screw ups and pay attention to noises!

Tony Bad

- ----- Original Message -----
From: Peter Brandt
To:
Sent: Tuesday, July 18, 2000 10:57 AM
Subject: Re: GMC: Mystery noise

>
> > Worrying about the noises, and finding out what is causing them is a
good
> > habit! In the 25 years we have had our coach we have made the mistake of
> > ignoring some noises and were usually rewarded with a good swift kick in
> the
> > posterior. When your GMC talks, listen!
> >
> > Tony Bad
>
> Thanks, Tony!
> I've been accused (by my wife) of worrying too much about strange noises!
> Peter
>
>
 
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