Rattle Diagnosis, hollow tapping sound at idle

[ExpeditionEnvy]

Trying to identify the source of a rattling coming from my 2000 Land Cruiser (USA, 2UZ-FE). It is only really at idle, and actually usually instantly stops if I touch the throttle at all. It is very inconsistent, appearing at random times seemingly unrelated to temperature, ambient or engine.

I would describe it as what you would expect tapping on a hollow pipe/tube ~tens of times a second. In the cab it is sorta muted and sounds like it would be coming up from vents. But the frequency of taps seems too low to me to be from something being struck by a fan and is unrelated to the a/c or heat being on. Tough to search for related threads by describing the sound, the "best" seems like it might be heat shielding on the cats, but I'm not sure.

Here is a video I managed to snag, it sounds a lot louder with both the window open and the wall next to me reflecting the sound. Any insight is greatly appreciated, Thanks!

 

[Trunk Monkey]

Could be the cat shields, somewhat common. Lay under the truck while it's idling to pinpoint where it's coming from.

 

[Mike NXP]

^^^ Rusty heat shields rattling for sure..... If you popped it in neutral right when you hear that noise it would prob go away as RPMs change ...

See what you can find on your own by looking around below. Start at your tailpipe and work your way forward...Sometimes the cage and weight on the back of the muffler rot out...Other times like mentioned heat shields around your cats can rattle...You can usually bend / tweak it to make it get quiet rather than needing to replace ...

Get a friend you trust who doesn't want to run you over. Have them man the drivers seat and work the engine a bit while you poke around.

 

[excessive]

sounds like a heat sheid rattling, probably the midpipe clamps have rusted

 

[rexington14]

I had a similar noise. It was my engine cover. Foam was deteriorated and I suspect it wasn't sitting right. I removed it.

 

[ExpeditionEnvy]

Thanks for the replies. I haven't been able to locate the source yet, but at least your responses give me the confidence that the rig isn't about to explode.

I was never able to find an audio recording of a similar noise, only descriptions so hopefully the video can help others too. The sound is way too inconsistent and brief to be reproducible or easily recorded.