I'm kind of puzzled over a recent sound that i have been noticing on an 06 hemi. It's the same sound when you go for a trip, turn your truck off, and you hear a metallic tapping sound from your exhaust manifold, as the metal cools.

In this case; however, i get an irregular tap, and I say tap, because i never hear two clicks consecutive, but i hear it when the truck is on, driving, and in park. It's not in sync. It may tap 10 secs apart, or 15-20 secs apart. I just recently starting hearing it, or I could have just started noticing it.

Any ideas? It really sounds like a manifold cooling off, but the truck is still on, and temperature outside can be 20 degrees, or 50 degrees.

 

The ticking is coming from the left catalyic converter. what could possible cause a ticking from it?

 

My Silverado had the same exact "tick" from the exhaust at random times while the engine was warm and coming from the same spot in the firewall, almost like someone was flicking the firewall with their fingernail and the firewall was a coffee can. I never paid it any attention. I just drove and figured it was just the exhaust and it was never gonna go away. i hot used to it and never noticed it after a while.
Maybe the exhaust was super tight and was just expanding from an improper mold????

My guess....It's the heat guards on the manifolds making the noise.

 

this is common with many heat shields