"marbles in a tin can" sound coming from muffler

[DavidT]

Hello everyone! I haven't been here in a while, but I'm still enjoying the SHO.
I recently noticed this rattling noise. It starts about one minute after startup, and lasts for a few minutes. The noise only comes from the PASSENGER muffler tip only. Could it be broken up cat. converter pieces, or could it be the muffler itself. I have Flowmaster 40's. They are only about 30K-40K miles old. My exhaust cutout has been capped for the last 6 months. Has anyone with Flowmasters had a similar problem? I haven't noticed any power decrease...

 

[1993MTXSHO]

id say it sounds like a cat broke up flow masters last wayyyy more then 40k miles, take a hammer and hit your cat decently hard but not real hard and see if you hear any pieces rattling around inside. If you do your cats are shot

 

[ShoREV]

I get that sound too from cold engine for a few minutes then it goes away. Another member told me that's common and he got it too. I'm unwelded so noises scare me.

 

[DavidT]

interesting... well, if it makes you feel any better, my sho has welded cam sprockets. Is yours just out of the passenger muffler tip too?

 

[midnightauto]

with the engine off just hit the bottom of the muffler with your hand if it is a busted cat you should hear the parts rattle around in the muffler. second option could be as the muffler heats up and expands a broken weld inside the muffler may be causing the noise until it expands just a thought