[mantonas]

I bought a 2003 WJ with a blown 4.7 V8 engine, and I am going to replace the engine with one that I have from a wrecked WJ. It would be relatively easy to replace the exhaust Y-pipe with the catalytic converters in it when the engine is out. However, it costs $350. Never having seen the car run, I don't know if the check engine light is on, or if there is a bad smell, or any of the other signs of catalytic converters that need replacement. How long should these last? Any opinions on whether I should change them? I would rather not spend the money right now.

 

[JeepFreak12]

If it has 192,000 miles on that motor i would personally change it. Magnaflow makes a decent universal one that is cheaper than most. You can also find stock type ones for around $200. Or you can run it without the cat but it will be a lot louder and you will have a check engine light on.

 

[sl1980able]

do it i just replaced mine on my 4.0 wj works real nice with new 02 as well.

 

[01grand]

For best performance I would replace the y pipe with cats, and put in new o2 sensors to play it safe, the OE denso sensors are fairly inexpensive on rock auto. You can also exclude the 3rd cat if you want, as there are no sensors on it. Slightly louder maybe but 24" of straight pipe is much cheaper than the 3rd cat.