Rear main seal noise

[Huw Powell]

> My 83 urQ is now making the infamous rear main bearing vacuum leak sound.

> 1-       Is there a relationship between oil quality/grade and this noise? Rear main bearing seal is supposed to be lubricated from inside, right? I am using 20W50 Mobil 1.

Right.  Oil can be implicated, in a roundabout way, though.  Running
dirty (or dino?) oil for a long time can cause a build up on seals,
letting them dry out, but keeping them sealed with crud.  Switching to
nice clean synthetic can remove this crud, exposing a failing seal to
oil which can now leak.  Or, as in your case, allowing air to be drawn
through the seal under crank case vacuum conditions.  (right?)

> 2-       What can I do to eliminate it, except removing the tranny/clutch and replacing it?

You are probably stuck with replacing it, although you could experiment
with seal-swelling oil additives in the short term.

> Last night I installed my snow tires and the recent tread on wheel bolt torque was fresh to my memory.  I removed the Ronal to install OEM steel A4 wheels.  So I cleaned the bolts very carefully, I used a torque wrench but some bolts were still showing a strange behavior.  The reason is wheel mounting flange thickness; steelies are only a couple of mm thick where alloys are 12-15 mm.  So, even after a good cleaning, the bolts were still difficult to wind past their usual resting depth, meaning the remaining threads are stretched or deformed, or still dirty. The solution was to wind-unwind many, many times with the impact wrench after another wire-brush cleaning.  Now I can easily wind them all just with my fingers. Maybe this might explain the 3-wheeler club ?

As I recall, steel wheels, being thinner, actually require different lug
bolts.  I'm not sure if they also have a different "cone" shape too.

I hope your bolts did not go through the hubs in such a way as to hit
anything, and that all is OK.  You might want to dig up more info on
this and keep a set of dedicated bolts for the steel wheels.

--
Huw Powell

http://www.humanspeakers.com/

http://www.humanthoughts.org/