Exhaust rattle is driving me insane

Hi everybody. I have searched the forums for this and I can't seem to find anybody who has had my exact problem.

I have a 2.7 4x4 with about 130K on the clock. There's a metallic rattling noise that happens when I'm in gear and OFF the throttle. It's hard to reproduce while in neutral and coasting. It sounds like it's coming from the rear of the truck. The rattle has persisted since I bought the truck at 99K. Here's some history and things I've tried:

-Checked all the heat shields and clamps, including the exhaust manifold shield. Everything is tight with good clearance. I can't find any loose or rusted clamps, there is really no rust on this truck. Doesn't seem like rocks are caught behind any shields.

-Tapped on components with a mallet. Cats seem fine, I don't suspect the honeycomb. It seems like the only thing with significant vibration that produces a similar sound is the muffler. Both rubber hangers are in place and seem fine, the rattle almost sounds like it's coming from inside the muffler.

-I replaced the clamp on the inlet side of the muffler. Rattle seemed to get better for awhile and came back.

-Ran a full tank of premium to rule out pinging/detonation. Rattle was still there.

-Took off stock skid plate. Rattles with or without skid plate. Replaced stock plate with Skid Row plate. Rattle is still there.

-I lifted the truck with an OME lift at 112K. I installed the OME exhaust hanger. It rattled before and after the lift.

-Replaced spare tire at 112K. Looks like the tire winch was done under warranty. Doesn't seem to be coming from the spare.

Has anybody had this issue or have any ideas? It's driving me nuts, I can't drive with the windows down without hearing my truck constantly buzzing! At this point I'm wondering if I should just try replacing the muffler.

Thanks!

 

Just a thought if everything else has been ruled out.

I had a friend that was driven just about crazy with a noise no one could find.

Turns out interior welds broke inside the muffler .

Now it was only found when the exhaust system was replaced when for giggles we cut the muffler apart.

 

I currently have a rattle coming from my oxygen sensor when on and off the throttle. The little plate on there rattles because of rust on the mid pipe. Just a thought

 

This is where I've arrived at. I guess I'll have to suck it up and buy a new muffler

 

Sounds kinda familiar. I’ve had a metal “rattle” for two weeks now. It sounded like it was in the engine compartment. I went under the truck the other day and basically right where the driver sits an exhaust clamp rusted through and broke. At idle or really slow speeds it rattles like crazy. Anyone know if that’s a piece that’s welded or can I replace it myself without welding?

 

I had a very similar rattle in my 4runner; in gear, no throttle, rear exhaust section making contact with the cross member I believe. New motor and transmission mounts ended up fixing mine. Good luck

 

All good suggestions, my better intuition would tell me that it is a now defective muffler which is damaged or has broken pieces on the inside based on the information you have given. There isn't a whole lot back there so it narrows it down quite substantially.

Now if I could just find where my god forsaken metallic rattle at random speeds is coming from myself. I get the feeling they are the secondary shock remote reservoir mounts which are rattling ever so slightly at speeds, as I could had swore I duplicated the issue as I was attempting to wiggle them one day.

These trucks just rattle themselves into oblivion unfortunately. 1st 2nd and 3rd gens, they're all the same.

 

Dang. How did you drill it down to the mounts? That sounds like a big job.

 

I had a failing flowmaster cat rattle on me. The internals separated from the walls.

 

Mine only happened once the engine was warm, so at first I thought it was an open loop/tune up issue. Eventually it clicked that it might not be the engine running rough, but rather play in the mounts causing excess vibration, that then traveled down the exhaust. A nice tight powertrain fixed it for me.

 

https://youtu.be/g_4DiywsSbk

I just did my transmission mount last weekend. Similar to the one they take out in the video- mine had cracking near the edges of the rubber isolator, but it did help improve (but not completely solve) my driveline vibration.

 

You have shrouds that have "maneuvered" Exhaust shroud at the head and exhaust shrouds underneath. They seem to rattle at a set resonance. A quick tack on with a welder fixed the rattle that I had on my exhaust shroud at the head on a Gen 2.

 

I thiiiiiink it’s the “shield” around what I think is the catalytic converter. The one bold rusted through and snapped and the bolt holding a clamp on rusted and broke and the clamp is off. So now the shield is just rattling like a mad man. Easy fix though.

 

Was under the truck today and had a look at the transmission mount. Looks solid with no cracks. Haven't looked at motor mounts.

I'm pretty convinced it's the muffler, I can hear things moving around in there ever so slightly if I tap it with a mallet. Maybe internal welds broke loose or something.

 

For me had a rattle at 146k when I was going 35~40 mph....

Pretty sure it was the cat slowly falling apart..sounded like metal rattling around inside metal can....after couple hundred it quit....
problem solved.....

 

Finally following up to this thread. I went ahead and ordered a Walker OEM-style stainless exhaust. While waiting I checked the motor and transmission mounts. They are in good shape.

Just dropped the stock exhaust and sure enough, it rattles when I shake it. Probably an internal weld failed, as others have mentioned.

Bolting up the new exhaust now, hopefully this resolves the issue for good! It was not a fun job separating the mid-pipe and muffler flange...

 

Glad you figured it out. I had a pebble lodge itself in my rear o2 sensor shield once and it drove me crazy figuring it out…

 

Aaaaand fix confirmed!!!

I can actually drive with my windows down!

 

I have had this exact issue for months now. Glad you have found a fix that works for you.