Bad Catalytic Converter?

[Doubeleive]

Ok, so the noise happened right after the manifold was removed to replace the bolts? I reckon that there is a broken stud or bolt in there making that noise and if not removed soon it will take out the cat.

ya that's a possibility too, might have to cut the cat off, take out the material and weld it back on

 

[02Z71Raven]

go by any muffler shop and see if they can tell if the cat heatshield is broken anywhere if so they can weld it, also a experienced employee may know right where to hit it with a hammer to stop the noise, your issue is not entirely uncommon. just annoying

Careful when you say ANY muffler shop, lol
There's some in my woods I wouldn't trust to put a clamp on.
I do agree though, that could be a break in a connecting point on the shield, but I ain't no expert and that's just a sound file on the internet, so....

 

[nick0789]

Thanks for the replies everyone.

I’ll be making a stop by the exhaust shop that did the manifold bolt job and let them figure it out.
once I know what the deal is I’ll provide an update.

 

[nick0789]

So the exhaust shop said it was a vibration coming from the flange where the down pipe meets the exhaust manifold. The solution was to grind down the triangle flange.

The problem? The noise is still there, and now the flange is all jacked up.

 

[OR VietVet]

That diagnosis makes no sense at all coming from them. The flange may be ground down but if still seals there, it will be ok. What did they say about the noise still there?

I am still not convinced that the noise is the catalytic converter broke loose inside. It sure sounds like an external rattle. Did you ever see if the rattle changes at all when in gear?

 

[nick0789]

They told me the catalytic converter was fine. They also said it was good to go when I picked it up: I didn't notice the sound immediately, only after it got hot so I don't blame them for that.
I'll check the noise when I get ready to leave work for sound level between gears and report back shortly.

 

[OR VietVet]

I am talking about idling in gear. Driving, the noise cannot be heard, right?

If a catalytic is broken loose inside, you can have the engine off and bang on it from underneath and hear the rattle of what is broke loose in there.

We may have talked about some of what I just said but I am lazy and did not want to go back in the thread posts and see.

 

[nick0789]

Noise levels were relatively constant between P, R, N, and D at idle (parking brake applied). There seemed to be a slight increase in reverse but that settled out in a couple seconds so that isn't something I'd rely on to tell me anything.

Being able to hear the noise while driving would be tough because I have a flowmaster installed. That said, I had a coworker apply a little throttle to it while I was under the tahoe and the noise went away. Once the engine RPM went back to idle, the noise came back.

With the engine off I can smack the catalytic converter and hear a vibration-sounding buzz (first video I posted) but that's it.

 

[OR VietVet]

Need to have a MORE QUALIFIED tech look at it and show you what he finds.

 

[nick0789]

Yea, I was hoping the owner of the shop was going to be the one working on it but instead I got a couple other guys. Luck of the draw sometimes.
It’s going back to the same place tomorrow since I paid and I’m going to make sure the owner looks at it.