jtschmoyer

Hey all, 08 Jeep Cherokee Laredo gas v6 has recently developed a rattling sound coming from under the car. I decided to craw under and discovered that when I tap on the one catalytic Converter i get the same noise as I do when the vehicle is running. I came to the conclusion that a honeycomb must have broken off and is free wheeling. I found a brand new direct fit front pipe for $340 bucks. I was wondering how hard of a job it would be and what other parts I may need when replacing the pipe. I do not want the replace the pipe if it will just cause more problems (ex. check engine light). I also am not sure what caused it to go bad in the first place so I do not want to replace it and the same thing happens again... Thanks all!

97grand4.0

Sounds like the cat broke inside. no way to tell here without having it in the shop. Also hard to promise that is what is making the noise. YOU should be able to re use the downstream O2 sensor even if you have to cut it out of the bung.

jtschmoyer

I am almost positive that is what the issue is and also what the noise is.From what i researched the guts of the cat (honeycomb) broke off and is just bouncing around. When i tap directly on the one cat, i get the exact noise. I am more concerned about how difficult it will to replace the whole pipe and also what caused it in the first place. i was hoping to reuse as much as I can, but whatever i have to get new/ should get new, I will while its torn apart.

97grand4.0

Ive done my own a few times and also have brought it to a reputable shop. mufflers and pipe bending is one specialty i am not set up for. That said, i have had luck with just a sawzall and my little arc welder, those pipes weld up pretty nicely, but there was a slight bend needed by the axle that never got made so i have a little rattling that I wish i didn't but oh well.

jtschmoyer

The replacement exhaust I was looking at is a "direct fit" stock exhaust for my exact jeep. BUT, i hear it never is actually that easy....lol if you don't mind me asking how much did a garage charge you labor for something like that and what did they all do?

Turbo X_J

Step #5
https://www.2carpros.com/articles/ho...ytic-converter

97grand4.0

Glad you asked. First, i waited an hour at Mavis Tire to get my jeep just in the garage, then they spent a half hour on the phone and said the California Emissions Cat converter ALONE was $575, part only. Of course you have to put that on, if you have Cal emissions. So at that point I just left, being disgusted. Not saying I did this, mind you, but I checked across the street at Advance Auto and the Federal emissions cat they had in stock for $125 and their other store across town had the tailpipe, only $35. So, um...
And I see ebay has the rear O2 sensor for about $10 and I hear it works with either fed or cal if you modify the plug with a razor knife.

jtschmoyer

If it works, it works! In the end you saved a ton of money and still got a brand new cat! Ive decided to take it to a dealer for another issue and figured while it's over there, I'll see if they can look at that also.

Willys55

the calibrations for the california cat are different as well as the O2 sensors, if you put the federal one on, check engine light will appear like an angry mother in law and haunt you all the days

Turbo X_J

4 different O2 sensors

97grand4.0

)Not on the rear sensor it won't.) I correct myself, you need the federal sensor to match the federal cat and that will work. Otherwise it will throw the code.

Willys55

for the 4.0L up to 2001 you are correct, but he has the 3.7L v6 from 2008.....different specs all around

97grand4.0

Ah, ok. I was wondering how long that would last.

jtschmoyer

Took it do Brown Daub today... they wouldn't even look at it, just said if it is rattling that is probably the problem and is 1800ish to fix, 1500ish for the part and then 2 hours of labor at 110 an hour.... Decided I will visit a few local shops or just buy the cat i found and do it myself, hoping for the best.

Willys55

good luck