[V6-12v] Replacing the driver's side cat on a 1994 90S procedure

[Clive Young]

Tom

 I am about to do the same thin you did,..

I took out more cat material from the muffler this weekend. I got my 2 cats 
from disccount converters. My cats are really noisy and I can't tell which 
side so screw it I'm doing both. I also have 2 new o2 sensors to put in at 
the same time. The job maybe a litle involved as I got universal O2 sensors 
and I need to splice in the connector.
How is youcat running ? mine is very noisy popping on deceleration so I may 
have a leak which is allowing oxygen into the cat causing detonation. I 
willlet you know how it goes as I am heading out for my bolts as we speak . 
Thanks for the tips.
----- Original Message ----- 
From: "Tom Christiansen" <tomchr at gmail.com>
To: "Audi list" <v6-12v at audifans.com>
Sent: Sunday, March 25, 2007 6:35 PM
Subject: [V6-12v] Replacing the driver's side cat on a 1994 90S procedure


> Folks,
>
> I just got done replacing the driver's side cat on my 1994 90S
> (front-wheel drive). It was less daunting than I had feared after
> hearing all the horror stories about broken studs and such.
>
> Here's what you need:
>
> * One catalytic converter (DUH!). I got a direct replacement from
> www.discountconverter.com for $200 including shipping.
> * Three M8 exhaust nuts for the downpipe. They run $2 each at the
> stealership. Or 35 cents each (AFAIR) from www.autohausaz.com.
> * Three M8 x 45mm hex head bolts.
> * Four M8 Uni-Torque nuts (lock nuts that can stand high temperature).
> * Anti-seize
> * Penetrating oil (Aero Kroil works really great! www.kanolabs.com).
>
> Start soaking the nuts (especially on the downpipe) in penetrating oil
> a couple of days before you intend to change the cat. The bolts on the
> tail end of the cat are pretty easy to reach. The nuts on the downpipe
> a bit more challenging but I was able to work the can up into the
> engine compartment from below without removing the belly pan.
>
> Replacing the cat is pretty straight forward. Remove the belly pan.
> Unbolt the cat. If you've done a good job with the penetrating oil
> this should be no biggie. At least it was in my case. Clean the header
> studs and apply anti-seize compound. The three 8-mm bolts go on the
> output side of the cat. The heads of the bolts should face aft.
> There's a seal ring that goes between the output of the cat and the
> tailpipe. This ring comes with the cat (at least it did on mine). In
> my case the new cat was a few mm shorter than the old one. If that's
> the case for you, just loosen up the clamp on the tailpipe and the two
> mating ends will come together as you tighten the three bolts. Then
> tighten the clamp (40 Nm). The fourth Uni-Torque nut is for the spring
> loaded bolt that holds the cat on the front. I don't know the size of
> the bolt -- it was in good condition on mine, so I didn't replace the
> bolt. But do replace the nut as lock nuts are only good once...
>
> The whole job took me 1.5 hours to complete not counting the time to
> jack up the car and clean the tools.
>
> Tom
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