KraegNET

My inspection (NJ) is in two months, and so far the only DIY repair work I've done on my XJ has been cosmetic or super easy. I have a check engine light for o2 sensor failure and know I need a new muffler and probably a new cat. Are these easily replaceable for someone not largely mechanically inclined? I've been researching numerous things that need to be fixed and I think it's time to start doing things on my own that seem easy enough.

Note: I do plan on buying a floor jack and jack stands this week to allow me to get underneath.

I need a new muffler due to rust and holes and i'm 90% sure that the rattle I hear when driving past highway walls or echoey areas is the catalytic converter. But from what I've read is that they can't be simply replaced due to numerous regulations. Is there truth to that or can I buy one and install myself? I don't plan to change pipe layouts or anything as I don't have a reason for that. Are there exhaust kits that come with mufflers and cats? If so, does anyone have recommendations?

I do have to get my brakes repaired as they (or one) lock(s) up when I stop <40 mph, and I watched my friend do a brake job and I'm pretty sure that's too complicated for my level right now. Of course I could find out what on my exhaust needs to be fixed when I go in for the brakes.

Those tasks asides, what are some other essential tools to have for DIY work?

BlueRidgeMark

Replacing the O2 sensor is pretty simple, but there is one trick: HEAT. Either heat the bung (the fatter part where the sensor screws in) with a torch or just driving around for a half hour. That thing will be almost impossible to get out any other way. A basic propane torch will do the job. That's probably easier than hustling to get it up on jack stands before it cools off.

It's also good to use a special O2 sensor wrench, but it can be done with a regular wrench. It's critical to get a good fit, or you'll round it off and be fighting with some vise grips or pipe wrench.

I don't know if anyone carries a bolt-up exhaust system for these. Try the usual online suspects. I just got a system for an 84 Chevy from Summit Racing, but I just did a quick check and all they have for Cherokees is cat-back systems. Probably not what you want.

If not, it's welding time, and that's best NOT learned on an exhaust pipe!

No problem with replacing the cat yourself, as far as I know. There's a big problem with removing them, though.

dzywicki

Brakes are a great place to start. A mity vac ( ) will get you everything you need to bleed brakes on an XJ. Calipers are cheap. I'd replace the flexible rubber lines at the same time if they have never been replaced. They are cheap and will definitely fail anytime after 100k miles.
For exhaust, I used walker components from Rockauto. I used the walker downpipe, muffler and tailpipe but used this cat converter ( ). HAs worked great for over a year now. Mine is a 1998 so may be different. I am sure there are universal fit cats for a 2001.
Worst part of replacing the exhaust is getting the old one off. Even if the cat is still good, it will be fused to all the other pipe. The rubber hangers are probably good, but the rear hanger most likely needs replaced.
On this image: https://www.rockauto.com/en/moreinfo...373666&jsn=453 it is part 36377. That image will also give you the other exhaust parts for a 2001. Walker is not the best, but definitely serviceable to get you back on the road.

PatHenry

x2 (or 3 or whatever it is) on the brakes as a good "beginner" job.

If you do the exhaust yourself, like previously mentioned you'll want a Sawz-all for cutting old pipes off.
I replaced the entire exhaust - manifold back - and it was like $400 for the parts. A 2001 will be more since there are 2 O2 sensors and I think the cat is more expensive.

The law regarding catalytic converters is that you must have them as originally installed - in other words, if you have a cat and it goes bad, you have to put a replacement one on. Some vehicles have more than one catalytic converter, it's possible that you have 2 (they changed it so 99 and earlier, 00, and 01 are different IIRC) but the typical setup is just the one. You can absolutely replace it yourself legally so long as you use a comparable part.
As others have said, since it's a pain to get the old stuff off and unless you're doing the entire exhaust, the new parts should be welded on, I'd say a shop is your best bet.

BlueRidgeMark

Yes, yes, yes, and yes!