hi there,
sure, try some ordinary cheaper gear oil as a test. I don't see how that
could hurt.
It's been a while......... describe the noise and WHEN it does it, again,
please.
And how old or new is the transmission ?
and why are you sure it's in the rear, and not the front, this noise ?
also the type of noise..........whirring, rumbling, high pitched whine, etc.

on listening to rear wheel bearings.....'in the air' .
first I do it with the tires and wheels on,
then with those removed,
and finally with the rear drums removed.

also.....if you have not actually seen inside your CV joints.....all 4 of
them......
you really need to know that those are not dry, or excessively loose.
I've seen many, many dry CV joints.
Not saying I think that's where the issue is.........just that you need to
be sure that's where it is not.

oh yes........WHEN  did this noise start ?
did it gradually develop, or did it start more suddenly, and if so, after
what work or changes to the van ?

Does it make the noise coasting down the road , engine off, trans in neutral
?
Answers to those questions would help us help you.
thanks, Scott
----- Original Message -----
From: "Walter Houle" <whoule@ecscontrols.com>
To: <vanagon@GERRY.VANAGON.COM>
Cc: "Scott Daniel - Turbovans" <scottdaniel@turbovans.com>
Sent: Tuesday, January 13, 2009 5:49 PM
Subject: RE: Transmission Noise ?

Here's the latest: I did the stethoscope trick last week using a
Louisville Slugger for an earpiece. It worked great, but I didn't hear
anything unusual. I heard what I thought were normal mechanical gear
meshing sounds. Maybe they sounded a tiny bit rough or gravelly but they
didn't get louder or worse with increasing axle rpm. They were
consistent on either side of the van, too. So, nothing conclusive.

Next I visited the shop that installed the new rear wheel bearings. They
were nice enough to tear both sides down and re-inspect everything. They
didn't find anything there either. The bearings looked fine, no scoring
or bluing, and the grease was very clean. So again, nothing conclusive.

However, the noise is still there. One thought is the bearings
themselves. They're SKF. Is there any reason to believe this brand runs
noisier than the original OEM ones? If so, we could try a different
brand of bearing, like FAG.

One other recommendation I heard is to temporarily swap out the Redline
MT90 with some heavy Valvoline stuff and to see if that damps out the
noise. If it does, then I can suspect a worn transmission. Is this a
safe test to do?

Thanks,
Walter
1985 Vanagon MT