Cat Replacement

[Spoon]

Hello, I'm working on an 81 IL6 258 base automatic wagon, and I've started work on replacing her bad exhaust parts which is everything from the cat to the tailpipe I can more or less figure everything out except for replacing the converter. I've never replaced one before and I could really use a play-by-play on it.

I'm also unable to find the location of the o2 sensor, as I've heard you're supposed to unhook that before removing the cat.

Although it does seem rather simple I'd rather not do something wrong and cost myself later.
 
Thank You

[eaglebeek]

The 02 sensor is just below the junction of the exhaust manifold and the header pipe. If you're going to replace the header pipe disconnect the 02 sensor, otherwise I don't know of any reason to disconnect other than to replace the sensor.

[Taylor]

It is definitely on the manifold. I bought the down pipe, crossover and tail pipe from rock auto years ago. Not sure if they still carry them. The muffler I got from advanced auto, a basic 2”. The cat is off a MK2 Volkswagen gti, they had 2” back then, plus it was free. Had two of them back in the 90’s
The muffler is rusted out, only lasted 8-10 years.

[Spoon]

The 02 sensor is just below the junction of the exhaust manifold and the header pipe. If you're going to replace the header pipe disconnect the 02 sensor, otherwise I don't know of any reason to disconnect other than to replace the sensor.

I appreciate it.

And just for clarity, since I am not replacing anything beyond my catalytic converter I have no need to worry about the o2 sensor throwing something in my computer. correct?

[vangremlin]

I don't believe the 81's had an O2 sensor, mine doesn't.  The O2 sensor came into play with the feedback carb, and the 81's just had a basic carb. 

I haven't replaced the cat converter myself but it should be pretty straightforward.  Pick up a universal one off eBay and adjust your exhaust to fit.  I may have a picture around somewhere, if I do I'll post it.

Good luck!

[vangremlin]

Here is a picture of my aftermarket cat, installed at Midas.  This one does have an O2 sensor installed as I added fuel injection to my Eagle.  Let me know if you have any questions.

[Spoon]

That should do it for me then.

Thanks for the helpful information!

[Taylor]

Here is one I found just a little bit ago. Did a generic search for a 2” catalytic converter.
https://www.autohance.com/magnaflow-54304-universal-catalytic-converter.html
https://www.summitracing.com/search/part-type/catalytic-converters/universal/yes?N=inlet-diameter-in%3A2-000-in

[Spoon]

After an extensive wait all of the components are now in my possession, and I went out earlier to get to work removing the pipes. I knew it would be difficult as they're molded by rust, as expected I was unsuccessful.

I'd tried heating the pipes points contacted by the clamps and applying pressure by smacking a tightened clamp with a mallet, didn't even move a millimeter.
I fear that I may have to cut it off and replace the entire exhaust system running back to the manifold. I'm not really in the financial place to do anything like that right now so I come asking if you guys have any ideas of how to get these pipes off without causing too much damage to them.

Thanks a ton.

Helpful information:
* The pipes I'm attempting to remove are the mid extension pipe from the cat and the cat from the first extension.

*I am willing to cut the cat if it'll help, but would prefer to stay away from that idea if possible. I'm planning to sell it to magnaflow for recycle money.

*I've been caking the pipes joints in PB Blaster and WD-40 every afternoon for a week.

*The clamps are already removed, I've replacements in hand.

Thanks again,
                    Spoon.

[Spoon]

I finally got the cat removed from the pipes but now before I install anything new I want to get new bolts in the connection between the manifold and the first pipe down.

Do you guys happen to know if there is a gasket within this connection? As I would definitely like to replace it.

[mudkicker715]

no gasket. it is a flared pipe that gets pulled tight onto the bubble flare of the manifold.

[Spoon]

thanks a ton!