Rattle from catalytic converter

[HotWheelsBurban]

We replaced the cats and attached pipes on the other 99 Burb, and it wasn't much fun as I recall. 2wd Burb, but on the driveway with the front up on stands, so there was some room, not a lot though.
I think it was all stainless steel, was Walker brand IIRC. But this was in 2009 or so, so not sure. Don't have the Burb or service records anymore.
I'm wondering if the occasional rattle noise I hear sometimes on acceleration is this. Sounds like gravel in a tin can....

 

[someotherguy]

If you're not a transmission wizard, it's easy to confuse catalytic converter rattle with transmission noises (especially if you've had a few 700R4/4L60/4L60E's fail on you and you're paranoid) - in the converters, the insulator band burns out and the core rattles around inside the shell. It sounds like transmission "death rattle" for lack of an official term. (also on the E transmissions don't overlook the heat shield on the passenger side, it can come loose and make a racket; mine is doing so right now because someone NOT ME stripped out one of the two bolt holes for it.)

Aftermarket fit of anything is going to be sketchy so be prepared to curse and hammer and shove. IMO the main issue with any type of aftermarket catalytic converter is how strict are the emissions laws where you live? Do they do a sniffer test or just visual inspection? I've heard tell of some aftermarket converters being lax on precious metals, causing some people a hard time passing the sniffer test. Here in TX nothing gets a sniffer test anymore because anything pre-OBD2 is old enough to be emissions exempt, and anything OBD2 passes/fails simply off noting codes and emissions readiness monitors when they plug it in.

Richard

 

[Macs Garage]

My catalytic converter rattled too. Honeycomb whatever it is made of had fallen apart. I cut it open on three sides on the bottom and pried a now door open. I fished out the pieces and welded it back up. Not legal, but a temporary fix until the muffler shop could get me in. That was two years ago and I never went back. Surprisingly never set off an O2 code.

 

[Dariusz Salomon]

If you're not a transmission wizard, it's easy to confuse catalytic converter rattle with transmission noises (especially if you've had a few 700R4/4L60/4L60E's fail on you and you're paranoid) - in the converters, the insulator band burns out and the core rattles around inside the shell. It sounds like transmission "death rattle" for lack of an official term. (also on the E transmissions don't overlook the heat shield on the passenger side, it can come loose and make a racket; mine is doing so right now because someone NOT ME stripped out one of the two bolt holes for it.)

Aftermarket fit of anything is going to be sketchy so be prepared to curse and hammer and shove. IMO the main issue with any type of aftermarket catalytic converter is how strict are the emissions laws where you live? Do they do a sniffer test or just visual inspection? I've heard tell of some aftermarket converters being lax on precious metals, causing some people a hard time passing the sniffer test. Here in TX nothing gets a sniffer test anymore because anything pre-OBD2 is old enough to be emissions exempt, and anything OBD2 passes/fails simply off noting codes and emissions readiness monitors when they plug it in.

Richard

I'm not sure what criteria they're using here for something as unusual as our trucks tbh. I don't think they know what it should do emission wise.
It's not tranny noises as far as I can tell as it can be clearly heard from the cat. First is I had P160-changed the 02 sensors,thenI had p420 few times,then I was hearing a resonating sound under load when taking off from standing still and now rattle so I believe it's the cat.
But thanks for the input-Imma take it to my friend who's a mechanic and we'll double check.

Another question-anybody tried to replace just one cat-not the while system? Trouble is the damaged cat is the one from driver side bank and it has a kink nearly at the cat inlet so it doesn't leave much space to put something there-like universal cat(these are easily available and using clamps could be an simpliest solution-welding more secure and better in general but not neceserily on old exhaust pipes).