Shinick

Hello! I have a 2001 Lexus LS 430 with 160k miles. Recently I start to notice a strange ticking/rattling/scratching noise (I don't know which word best describes the noise lol) that seems to come from the engine bay whenever I put my foot down and the RPM reaches over 2,000. Internet search results range from a loose heat shield to a cracked exhaust manifold, so I'd like to get some expert opinion in this forum to help me better pinpoint the problem.

Attached is a video (https://youtube.com/shorts/wsfB0_Wnp5s?feature=share) of the noise. I'm sorry for the bad sound quality but the noise should be noticeable in the latter half of the video.

BigBoomer

I couldn't hear anything. To trouble shoot issues like that you will need someone to press the throttle whilst you walkaround the car and listen everywhere.
These cars are so well sound-proofed that trying to identify a noise from inside the car is all but impossible, unless the cause is in the cabin.

Duck05

Could be a worn serpentine belt and bad alignment. Had those same exact symptoms a few months back. Relatively inexpensive repair (around $150).

Not too far off from a full (TB, water pump, thermostat and parts) timing belt service, though. If you do not know when or if the TB has been addressed might be best to get it all done at once. Figure $1200-1400 at a reliable independent shop (don’t go any where near a dealership).