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Rattling sound...?

2K views 23 replies 7 participants last post by  frenchy206 
#1 ·
03 TJ has 100k. There is a metallic rattling when driving, under load. Sound goes away at idle or coasting. I checked everything underneath. All heat shields are secure and everything is snug and not rubbing on anything.

After reading other posts, it seems like the only thing it could be are the two small cats. What do you all think?

Btw, I don't seem to have power loss nor do I have any cel.
 
#3 ·
I had a similar sound coming from what sounded like my trans tunnel. I was the a/c fan/heater core?.... im not sure what exactly its called but I was able to replicate the sound by wiggling the air duct next to the gas petal. All I had to do was tighten a nut in the engine bay on the fire wall. Not sure if this is the sound you are hearing but its worth a look.
 
#7 ·
The heat shield on my TJ's muffler would rattle pretty bad under load after it warmed up a few minutes despite the fact that it appeared to be still firmly secured to the muffler. Tack welding the corners to the muffler fixed the problem.
 
#8 ·
Not sure what the mini cats are supposed to sound like when hit with a mallet, but when I hit them they had a metallic sound. Not a dull thud, but as if something was not completely solid.

Other than the cats, I'm not sure what else would create this noise. At 100k, I'm thinking they're life is nearing the end anyways.

So, if they are in need of replacement, who makes the best replacement. Also, while replacing, what else do you recommend I replace while there?
 
#11 ·
When I replaced the cats on my K1500, I used Magnaflow direct fit replacement cats and pipe system. The mandrel bends and fitment were excellent.

I believe Magnaflow sells a setup to replace the mini cats on Jeeps. That is what I plan to use when needed, however I have not seen any reviews. I would take a look at what Magnaflow has to offer.

I went cheap on the cat back system on my truck. Used Walker parts and regret it now. The bends were normal, restrictive pipe bends. I wish I had spent the extra money for a better, mandrel bent system. Look carefully at the bends on the Walker product.

I have read a few threads regarding the Bosal product and some minor fitment issues, but overall they seemed positive.
 
#16 ·
I called the dealer and got the Mopar part numbers for the sensors. I matched them up on RockAuto and save nearly half of what it would have cost going through the dealer.

Just for reference, here are the part numbers.

56041944aa
56041943aa
 
#20 ·
I got the new Magnaflow cat system installed. Overall, the fit and finish was very nice. I do have several questions though.

First, after install, I started up the Jeep and it smoked real bad out the tail pipe. Was this normal? It went away after driving for a while.

Second, I wanted to replace all my O2 sensors. I ordered the part numbers listed earlier in the thread. These were the numbers I was given by the Jeep dealer. The up stream (before the cat) sensors had the correct connection. The downstream (after cat) sensors didn't and therefore I had to use the old ones. I called the dealer and they didn't have a solution. I did find another part number on RockAuto. Mopar 56041847AA. I ordered 2 of these, so hopefully they will work.

Third issue which was the reason I started this project, was a rattle. Well, it's still there. I really have no idea what the hell is causing this metallic rattle. It happens when reving the engine or accelerating. I don't hear the sound until the Jeep has fully warmed up. It's not anything in the dash. It seems to be coming from under the Jeep. So, if you have any other ideas it'd be much appreciated.
 
#21 ·
I got the new Magnaflow cat system installed. Overall, the fit and finish was very nice. I do have several questions though.

First, after install, I started up the Jeep and it smoked real bad out the tail pipe. Was this normal? It went away after driving for a while.

Second, I wanted to replace all my O2 sensors. I ordered the part numbers listed earlier in the thread. These were the numbers I was given by the Jeep dealer. The up stream (before the cat) sensors had the correct connection. The downstream (after cat) sensors didn't and therefore I had to use the old ones. I called the dealer and they didn't have a solution. I did find another part number on RockAuto. Mopar 56041847AA. I ordered 2 of these, so hopefully they will work.

Third issue which was the reason I started this project, was a rattle. Well, it's still there. I really have no idea what the hell is causing this metallic rattle. It happens when reving the engine or accelerating. I don't hear the sound until the Jeep has fully warmed up. It's not anything in the dash. It seems to be coming from under the Jeep. So, if you have any other ideas it'd be much appreciated.
1. Completely normal

2. It seems like parts numbers are mixed up for some years on the O2 sensors. The sensors themselves are the same. It's just the plug and pigtail length that's different. You can either experiment and find the right one or splice your old plug on to the new sensor.

3. Sounds like you have a contact issue somewhere with your new exhaust. Trial and error to find it.
 
#22 ·
Just an update. After spending considerable time trying to find this rattle, I broke down and brought it to the dealership. I've used them before, so they know the history on the Jeep.

They too checked everything and believe that it is a baffle in the Thrush muffler that is loose. It seems hard to believe since I've put less than 10k on this muffler.

What do you think? Does it sound possible?

I like how it sounds, but don't want to have to replace mufflers every few years. Should I go with a different brand? If so, which one? I'm not after crazy loud. I like deep, almost diesel sound.
 
#23 ·
Well, I went ahead and replaced the muffler. I went with a Magnaflow. I haven't driven it much, but so far I like it. It sounds a bit smoother than the Thrush that was on there. When the hammer is down and the revs are past 3k, it really sounds mean. I haven't heard the rattle, so I think that problem is solved.

I'm still working on replacing the after cat O2 sensors. Hopefully this week I'll figure it out. I'm going to have a few hundreds in returns from
 
#24 ·
I just received some more O2 sensors from RockAuto. If anyone is interested, here are the Mopar part numbers needed for each sensor. Each one has a different number due to wire length and plug difference.

Upstream (before cat) 56041943AA & 56041944AA.
Downstream (after cat) 56041847AA & 05139825AA.
 
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