low rpm rattle muffler or cat?
Thread Starter
Junior Member

Joined: Sep 2012
Posts: 75
Likes: 1
From: Oswego, IL
Year: 2001
Model: Cherokee
Engine: 4.0L I6
when im stopped at the light i get a low rattle. it goes away when i take off or if i put in park. is that the muffler or cat going? or is it maybe just lose.
The entire exhaust is stock. it has 137k.
Next question is - if i decide to replace the entire exhaust system what to go with. i tried to search and found some threads talking about performance curve flowmaster 40 kit. I could not find a list for all i need to order.
Can someone spell it out for the ones who rode the short bus.
I am not messing with headers or glass packs, just need from the factory header back to the bumper everything included reducers, hangers. I will take to a local shop to have it installed and want it all to work obviously so i dont look like a moron.
as for sound not looking for "look at me" loud just a nice growl when i accelerate so people say wow kick *** jeep.
The entire exhaust is stock. it has 137k.
Next question is - if i decide to replace the entire exhaust system what to go with. i tried to search and found some threads talking about performance curve flowmaster 40 kit. I could not find a list for all i need to order.
Can someone spell it out for the ones who rode the short bus.

I am not messing with headers or glass packs, just need from the factory header back to the bumper everything included reducers, hangers. I will take to a local shop to have it installed and want it all to work obviously so i dont look like a moron.
as for sound not looking for "look at me" loud just a nice growl when i accelerate so people say wow kick *** jeep.
Seasoned Member
Joined: Sep 2012
Posts: 461
Likes: 0
From: charlotte
Year: 2000
Model: Cherokee
Engine: 4.6L stroker
Sure its not your factory plate that covers the side of the gas tank that shields it from.your tailpipe? Mine is doing that right now and its driving me crazy
Junior Member
Joined: Apr 2010
Posts: 33
Likes: 0
From: Denver, CO
Year: 1998
Model: Cherokee
Engine: 4.0l 6
I had the same thing. When I was in neutral at idle it would rattle, when I increased the rpm's it would go away. It sounded like it was coming from the transmission. I had a mechanic check it out and it was something loose inside the transmission. They tightened it up and he noise is gone. Can't remember what it was called though.
Originally Posted by carlover77
I had the same thing. When I was in neutral at idle it would rattle, when I increased the rpm's it would go away. It sounded like it was coming from the transmission. I had a mechanic check it out and it was something loose inside the transmission. They tightened it up and he noise is gone. Can't remember what it was called though.
I have the same thing and can look into it today, a saturday. I thought it would be the exhaust rattling on the cross member to the frame but I'm not sure. I just put 2" lift shackles on and it made it worse. I am hoping that someone might be able to post something to let me know what to expect.
Senior Member
Joined: Apr 2012
Posts: 735
Likes: 0
From: Los Banos CA
Year: 2000
Model: Cherokee
Engine: 4.0
My 89 has the same problem so I will be watching this thread. I'm hoping its just the cat shield since I just got my flowmaster welded on after 5 months without a muffler.
Trending Topics
Thread Starter
Junior Member

Joined: Sep 2012
Posts: 75
Likes: 1
From: Oswego, IL
Year: 2001
Model: Cherokee
Engine: 4.0L I6
Very interesting. Did not know I was tapping into a common issue. I guess I will have to get under there and look to see whats going on. My heat shield covering what im not sure maybe the cat got ripped off after hitting some deep water at a decent speed.
I will see if pinpoint it down. the transmission comment was interesting. i thought for sure its exhaust related but who knows.
UPDATE: SAT 2:41 PM
okay so i could not produce it as loud as before but found the same rattle and it sure looks to me to be the muffler. I kept in gear creeping until i got the sound then put on the parking brake to take a look
(keeping my head away from the tire naturally - safety first) I could see the muffler shaking slightly. everything else appeared to be solid. no hole in the muffler but everything is rusted to ****.
maybe its the connection between the back of the muffler and the tail pipe section. i dont know. i think its the muffler. just doesnt seem like cat or trans.
I will see if pinpoint it down. the transmission comment was interesting. i thought for sure its exhaust related but who knows.
UPDATE: SAT 2:41 PM
okay so i could not produce it as loud as before but found the same rattle and it sure looks to me to be the muffler. I kept in gear creeping until i got the sound then put on the parking brake to take a look
(keeping my head away from the tire naturally - safety first) I could see the muffler shaking slightly. everything else appeared to be solid. no hole in the muffler but everything is rusted to ****.
maybe its the connection between the back of the muffler and the tail pipe section. i dont know. i think its the muffler. just doesnt seem like cat or trans.
Last edited by stimp774; Jan 26, 2013 at 02:45 PM.
Junior Member
Joined: Apr 2010
Posts: 33
Likes: 0
From: Denver, CO
Year: 1998
Model: Cherokee
Engine: 4.0l 6
Junior Member
Joined: May 2008
Posts: 15,016
Likes: 11
From: +34° 25' 35.67", -81° 21' 12.04"
Year: 1993
Engine: 4.0
I was going to suggest the exhaust rattling on the cross member. I see that all the time.
Btw, 75 bucks wasn't bad but next time you can do that yourself with 2 wrenches and about 15 minutes.
Btw, 75 bucks wasn't bad but next time you can do that yourself with 2 wrenches and about 15 minutes.
Thread Starter
Junior Member

Joined: Sep 2012
Posts: 75
Likes: 1
From: Oswego, IL
Year: 2001
Model: Cherokee
Engine: 4.0L I6
sorry to be such a newb but where is the cross member at? i dont know where the mounts are either for that matter.
to carlovers point mine seems to be coming more from the back.
when im in the jeep i hear it coming from the back over my right shoulder. but its harder to identify when i go look at the same spot from outside.
Nothing looks looks its all so rusted, but when i try to move it by hand its all solid in place. the only thing i noticed was a slight vibration in the muffler.
to carlovers point mine seems to be coming more from the back.
when im in the jeep i hear it coming from the back over my right shoulder. but its harder to identify when i go look at the same spot from outside.
Nothing looks looks its all so rusted, but when i try to move it by hand its all solid in place. the only thing i noticed was a slight vibration in the muffler.
Junior Member
Joined: May 2008
Posts: 15,016
Likes: 11
From: +34° 25' 35.67", -81° 21' 12.04"
Year: 1993
Engine: 4.0


