So, today I found my rear (2nd) catalytic converter broke from the front exhaust pipe where the flange gasket was. Upon further inspection turns out all the bolts and gaskets are rusted or missing.

I have a 2001 Jeep Cherokee xj (CA emissions) with those pre-cats. But since I am replacing only the rear cat that is under the body near the muffler I can just buy any cat that fits an xj, correct? Any recommendations on a good/affordable high-flow rear cat that won't fit the bank?

Also,
which size flange gaskets and bolts should I use for connecting both sides of the cat to the muffler and front pipe/manifold?

 

Do you have access to a welder?
If so, cut out the old rusted pipe and weld a new piece of $7 pipe onto the existing Cat flange. That's what I did last fall (same issue for me).

Thats one idea.

 

I do but I am replacing the entire exhaust systems from the front pipe, cat, muffler, and tail pip as it's all rusted pretty badly. I don't mind welding a cat to fit if it's universal and saves me a good amount of money. Only could find one direct fit and it was a tad bit pricey. Ideally, I don't want to spend more than $130 as long as its high flow. I think there are some spun ones out there but haven't seemed to been able to find them.

 

The catalyst must be a california air resource approved type to pass the smog test. An approved catalyst will have an approval number attached to it. the smog guy is supposed to confirm this number. If it is missing, or unreadable (say number is obscured by floor or heat shield) the truck will fail the test). ( dont weld it in upside down, number facing floor!)
A cheaper non California catalyst will fail your truck, even if tail pile result is perfect.

good luck

 

Thats the thing though. It the main cat in the rear with no 02 plugs. I get that the other cats should be CA but shouldn't it matter for the main CC under the body? I don't even live in NY or CA or CO anyways. Cars 20+ years old and doesnt even need to pass emissions per MA law.

 

If no O2 sensor down stream of that catalyst, then you may straight pipe it or use a hallow catalyst until you can instal a new catalyst as the engine wont care, it will run perfectly fine this way.
You may use a non California catalyst if no need to pass any test strict test, install a catalyst to keep air a bit cleaner if you can afford it, and live in an area where catalyst thiefs are rare. The motor wont care, it will be perfectly fine with non California catalyst, no catalyst.

good luck in good priced cat hunt!

 

Thanks man! That is some great advice! I would def straight-pipe it but my concern is that it would be way too loud for my neighbors. So if I get a non-california cat it will still be OK to use on my 01' XJ since the 3rd cat under the body does have 02 sensors? Am I right?

 

Odd, there's an active thread on another forum with the exact same question.

My reply there is:

"Are you sure it's a CAT? The CA Emissions vehicles have the 2 cats attached directly to the manifold with O2 sensors right before and after (as you've noted). The parts manual shows a "resonator", part # 52019 500AD, in place of the of the cat before the muffler."

 

I know as a first hand fact that the 2001 california xj has three catalysts.

 

I bought this one:

Thoughts?

 

The description on that page is confusing - "Federal EPA Compliant. All Federal catalytic converters meet EPA requirements. Federal Catalytic Converters are not legal for sale, installation or use in the state of California and Colorado" and "OEM Grade Formulated for vehicles with California emissions systems in Federal markets"

The manf page also says "Note: Not for sale in California", implying it does not meet CARB standards which Massachusetts has also adopted, even though their video says OEM grade meets california standards.
https://www.magnaflow.com/products/5...onverter-51205

 

I agree, I thought so too. That's why I was taking so long to figure it out. So, I'm going to give it a hot. As long as it doesn't throw any codes or runs lean then I'm good. CARB or NO CARB I don't think it matters bc the vehicle is over 20 years old and doesn't need to pass emissions and they can't prove it was installed after the change.