[s-cars] oil burning on cat converter

Fred Munro munrof at sympatico.ca
Mon Aug 2 13:05:30 EDT 2004

Hi Jerry;

Burning transmission oil has a unique smell, so I assume that is how you
determined it was transmission oil rather than engine oil. Burning Pentosin
(central hydraulic fluid) also smells like burning transmission oil.

The old '86 - '88 O16 trannies were filled to the bottom of the filler plug.
All later trannies specify a certain volume of fluid. I've been draining the
tranny completely and adding the specified volume - it usually ends up below
the level of the filler plug, so you may have had too much oil in the tranny
and it foamed out the vent. Was there any signs of leakage to indicate your
tranny oil would be low when you topped it up 6 months ago?

I had a similar problem on my '94 S4 but it was a leaking rear seal. Sure
stunk after a drive!

Fred Munro
'94 S4

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of Jerry Scott
Sent: August 2, 2004 11:07 AM
To: s-car-list
Subject: [s-cars] oil burning on cat converter

While on my way to Vail from Denver over the weekend in the 93 S4, I hit
speeds over the 100 mark on Vail pass.  When I got into Vail, I noticed
a smell of burning oil and smoke coming from under the car.  It appears
that transmission oil is coming from somewhere on the rear of the trany
and being blown by the wind onto the bottom of the passenger side cat.
converter.  After returning last night to Denver, the situation did not
seem to repeat.  About 6 months ago, I checked the level of the oil in
the trany and found it to be about 1/3 of a quart  low, so I filled it
to the top of the fill plug and have had no leakage problems until now.
I am thinking that this may have been caused by the oil being churned by
the high speed driving and thrown out the vent on the top of the case.
This plus driving at 10,000 feet elevation may have caused the problem.
Should I have not filled the trany to the top of the fill plug and has
this occurred to anyone else?  It doesn't appear to be a leak at the
rear shaft, but I guess this could be the problem.  This is the standard
5-speed stock trany.  Any comments appreciated.
Jerry Scott

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