Loud annoying rattle coming from exhaust manifold at low rpms

[Socalsunrise54]

Been having it since the day I bought her last year. Its basically a loud "tinny" rattle whenever I'm at a red light just above 600rpms as well as when in reverse. It essentially only happens when the rpms drop. When I hit the gas it goes away. I got under my rig and diagnosed the problem by banging on the underside to spot the problem area and realized it's coming from the exhaust line/rusted parts etc...but cant pinpoint the exact location its coming from. Underneath the truck its about half way from the front to the rear, starting just behind the transfer case and working it's way to the back. If I grab the tail end of the exhaust I hear the same pitch of the rattle I'm hearing so I know I'm getting closer to finding it but nothing for sure yet. Furthermore once I find the culprit, how do I stop the rattling? I've already checked and know that it's not the heat shield. Thanks for looking!

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[thezentree]

I bet it's the heat shields on your catalytic converter(s). Go smack one of your cats and see if that causes the rattle.

On mine, a couple of the bolts and nuts that clamp the heat shield around the cat had rusted away and that rattle had been driving me nuts for a couple of months until someone here suggested it might be them. I had ruled them out by shaking the exhaust and not being able to reproduce the rattle. Smacking the exhaust did it though. A couple leftover stainless #10-32 screws and nuts later, problem solved.

 

[tx_shooter]

At 200k miles I had a similar rattle coming from my exhaust system. I ended up tracking it down to loose material in the muffler resonating through the pipes. I replaced the muffler and exhaust pipe past it all my issues went away. That was 100k miles ago now.

 

[S1996R]

I have seen heat shields, small rocks, catalytic converter, or the innards of the muffler all cause noise at low rpms.

 

[JRZEE2000TR4LTD]

The substrate has broken away from inside of the catalytic converter.

 

[Mudeprived]

The substrate has broken away from inside of the catalytic converter.

This.

I just replaced my cats because of this issue. The front cat deteriorated and clogged the rear.

 

[turbo8]

My annoying rattle was coming from my old flowmaster muffler. I replaced it last night, rattle is gone.

 

[4x3Lander]

Been having it since the day I bought her last year. Its basically a loud "tinny" rattle whenever I'm at a red light just above 600rpms as well as when in reverse. It essentially only happens when the rpms drop. When I hit the gas it goes away. I got under my rig and diagnosed the problem by banging on the underside to spot the problem area and realized it's coming from the exhaust line/rusted parts etc...but cant pinpoint the exact location its coming from. Underneath the truck its about half way from the front to the rear, starting just behind the transfer case and working it's way to the back. If I grab the tail end of the exhaust I hear the same pitch of the rattle I'm hearing so I know I'm getting closer to finding it but nothing for sure yet. Furthermore once I find the culprit, how do I stop the rattling? I've already checked and know that it's not the heat shield. Thanks for looking!

Sent from my SM-T837A using Tapatalk

This sounds exactly like the sound I am hearing as well. I also need to figure it out because it drives me nuts. I thought it might be the front license plate being loose, but that didn’t fix it. Thought it was the front “mini” skid plate. Nope. I guess I will check out the catalytic converter area to see if that is where it’s coming from.

 

[1biker]

This.

I just replaced my cats because of this issue. The front cat deteriorated and clogged the rear.

I too had the rattle, bugged me to no end. I finally narrowed it down to my Cat, or within my Cat I should say. The internal filter material was completely intact (only had 88k miles on it, but 20 years of time), my mileage was great, passed emission etc. But I replaced it anyway and now the rattle is gone. Must have been a little piece that was loose and rattling around. I removed the Cat heat shields to verify it was internal, it was.

 

[Mudeprived]

That was my noise maker.

 

[thenightman]

I had a similar sound, It was the cat heat shield on one side. Two of the four tacks that hold it on broke. I retacked it, no more noise.

 

[Jsbcarman]

Mine was the crossover pipe , couldn't remove it so we clamped the shield , rattle gone thankfully.

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[4x3Lander]

Well, I discovered what my rattle was. The bottom two holes for the cat heat shield were attached, but the top two holes were not. Seems maybe the screws / bolts were not even attached. I didn’t feel like pulling the whole system down to put bolts I don’t have in them. I zip tied the two top holes and voila!

 

[Greenmachine86]

I think that must the rattle im hearing at low speeds, guess im gonna try the coverter first then

 

[TexasToyota]

Rattle

Hey all - I just took this video, mine has been rattling now for 6 months or so and it's finally bugging me enough to investigate. Is this the rattle/sound y'all were having? It's a short 16 second video - YouTube

So looking at the comments, could be some bolts, or the cat itself?

Rock auto has those for $140 or so it looks like https://www.rockauto.com/en/catalog/toyota,2001,4runner,3.4l+v6,1375163,exhaust+&+emission,catalytic+converter,5808

 

[gamefreakgc]

Hey all - I just took this video, mine has been rattling now for 6 months or so and it's finally bugging me enough to investigate. Is this the rattle/sound y'all were having? It's a short 16 second video - YouTube

So looking at the comments, could be some bolts, or the cat itself?

Rock auto has those for $140 or so it looks like https://www.rockauto.com/en/catalog/toyota,2001,4runner,3.4l+v6,1375163,exhaust+&+emission,catalytic+converter,5808

Wow, that's a heavy rattle. Get a rubber mallet and start hitting things, cat, muffler, frame, etc. and see if you can duplicate the sound. It might be just the video, but that sounds large and heavy and not like the cat heat shield.

 

[tx_shooter]

Hey all - I just took this video, mine has been rattling now for 6 months or so and it's finally bugging me enough to investigate. Is this the rattle/sound y'all were having? It's a short 16 second video - YouTube

So looking at the comments, could be some bolts, or the cat itself?

Rock auto has those for $140 or so it looks like https://www.rockauto.com/en/catalog/toyota,2001,4runner,3.4l+v6,1375163,exhaust+&+emission,catalytic+converter,5808

With the exhaust system cold; get under the 4R and tap/ shake the different parts. Start with the muffler and then move your way forward. Also check the exhaust hangers are in tact. I have seen where one of the hangers was bad allowing the exhaust to pull to one side and make contact with other metal.

 

[JRZEE2000TR4LTD]

Hey all - I just took this video, mine has been rattling now for 6 months or so and it's finally bugging me enough to investigate. Is this the rattle/sound y'all were having? It's a short 16 second video - YouTube

So looking at the comments, could be some bolts, or the cat itself?

Rock auto has those for $140 or so it looks like https://www.rockauto.com/en/catalog/toyota,2001,4runner,3.4l+v6,1375163,exhaust+&+emission,catalytic+converter,5808

Looking at the video, the exhaust isn't shaking at all so my guess is the substrate in the cat has broken away and is really loose or something has broken away inside the muffler. All the external stuff can be easily found and ruled out.