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

Tom Christiansen tomchr at gmail.com
Sun Mar 25 18:35:18 EDT 2007


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.


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