2000 4.0 cali emission
So I have suspicions that my header is cracked. Hissing noise from engine bay (already checked for vac leaks), smell of gas in the cab sometimes, running rich. I also would like to let the 4.0 breath better so im looking into a new header. I dont have many choices cause i have the cali emission cherokee and have that dual mini cat set up. I found a banks header that would work and also a high flow two piece cat setup that I need. Im wondering where i would find that mid piece that is right by the front axle, after the 2 cats and before the third cat. And also, if i still need the third cat since I have the 2 already before. I would like to save money any way i can and if i dont need that third one that would be great. There arent any sensor in the third one so it wont set off the engine light, right? Thanks for the help.

 

You sure one of the manifolds itself is cracked? These things are NOT cheap and don't break very often. Remember the whole assembly is like 5 pieces so a leak at a joint is much more probable.

Check for leaks the same way you would with a BBQ: let the piping cool down and brush soapy water on everything. Fire up the engine and look for bubbles.

 

I could have sworn i read on this site that the exhaust manifold cracking was a very common problem?

 

Yes, on the 4.0Ls with a single cat. The reason is that the OE manifold is a very long piece of cast iron with little structural integrity:



The one pictured is an aftermarket replacement which has bellows sections in the first and sixth runners, which reduces stress and prevents the thing from cracking. XJ exhausts do not have any flexpipe in them, so the entire weight of the exhaust system gets pushed around when the engine vibrates. They usually crack at the welds where the larger pipes join to meet the downpipe.

California emissions models with 3 catalytic converters are quite different:



If they were to crack it would probably be at the same spot, but it's not as likely as the giant solid manifold used in previous years. It wouldn't surprise me but be sure to check. That section includes the mini-cats which really are expensive.

 

yeah tell me about it. about 500 for the header and 200 for the cats. Ill do some more digging to see if it really is cracked. I eventually do wanna upgrade so maybe this will put it at the top of my list. thanks.

 

does anyone know if deleting just the third cat would okay?

 

Yep. It's not. Violation of federal law and against the rules of the site. There are a lot of options for high-flow converters though. Really cheap too. I think performance-curve.com is one of the popular sites

 

okay thanks salad. Do you have any experience with catco, walker, or eastern cats?

 

Walker seems to be well recieved here. There are a few other rands on that site I've seen mentione positively. I'm waiting for mine to fall off from the rust

 

The walker cats must be decent, I've sold a good few at work with no complaints really, granted its the only brand I sell LOL but I've never heard anyone telling me they were crap. Also, they're only like 150 for a new cat...except cali which is closer to 2-300 depending where/ who you got it from

 

Just did my whole exhaust with walker.. no complaints.

 

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Found out walker makes everything I need. the dual cats, the one pipe piece after, and the third cat and its all reasonably priced. So I am going to go with walker. Thanks guys.

 

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