banging noise

[lukbrw]

This is a goofy one. For the last couple of months, while driving we've been hearing this noise that sounds like a loud bang on a metal garbage can. The recently, when parked in the garage, out of the blue I will hear it again.

Did the same thing last night. Pulled the truck into the garage for a wash, about five minutes later, bang. Sounds ilke it's coming from behind the cab under the bed someplace. Gas tank??

It's a 2000 Silverado 1500. Z71. 180,000 miles.

[kaycee]

Catalytic convertor, maybe

[lukbrw]

The cat was a thought also, but from what? Pressure? It's just wierd when the truck is parked in the garage not running and then five minutes later....bang. LIke someone is under the truck with a hammer.

[straitnate14]

mabey the honney comb is loose in the cat and moves around with the expanding and contracting of the metal ?

[Josh]

Muffler heat shield most likely, take a look at it for broken spot welds. The spot welds break because the metal the muffler and the heat shield are made out of expand and contract at different rates... GMs fix and the only thing that does work is installed a long worm gear clamp over the spot welds to help hold it in place or to cut off the shield and clamp a new one on.