Something broke lose in catalytic converter?

[GreatDaneHummer]

I went wheeling today and now there is a pretty loud rattle coming from the exhaust pipe by the catalytic converter. If I knock on it you can hear the same rattle. Any ideas what to look for? I can't see any cracks etc off hand. I have read a few things about motor mounts breaking but have never heard what it sounds like. Power seems to be the same and shifts ok. Ideas? And good mechanics in the down town Chicago area that actually knows what a Hummer even is lol?

 

[JPaul]

Which cat? The one at the exhaust manifold or the other cat under the chassis? If it's rattling and it's not a broken clamp or bolt or something, it could be the matrix inside the cat has broken loose. That could cause rattling inside the cat. If that is what it is, then you're probably going to need a new cat soon. It might be ok for a while, but if part of the ceramic matrix inside the cat has broken loose, then it will probably eventually completely fail and possible cause clogging in the cat and kill our power. Or it'll just be noisy until you replace it.

I could also be totally wrong, but I have a hunch that is what it is.

 

[IISPEEDYII]

Or it could be a broken heat shield somewhere. That's happened to me twice now.


Sent from my iPhone using Tapatalk

 

[CaseyS]

Probably the guts of the cat. Mine did that several years ago. Just cut it out and put a piece of straight pipe. You already have a cat on the manifold. It won't throw any codes with that one gone.

 

[Mr_Rich]

It's very common. The catalyst will start breaking down to smaller chunks and start spreading through the exhaust pipe depending on how long you let it go. Find a good muffler shop.

 

[Ryan212]

Remember cats are covered by an 8 year 80k mile warranty on most gm vehicles

 

[alrock]

Probably the guts of the cat. Mine did that several years ago. Just cut it out and put a piece of straight pipe. You already have a cat on the manifold. It won't throw any codes with that one gone.

Correct, for 07 and newer H3s. On the 06 models, the two O2 sensors monitor both cats. On 07 and newer, the second cat is not monitored by O2 sensors. Also, be sure to be compliant with local and federal emissions laws.

 

[scoreh3]

Yes they are , that's how I got them to replace my cracked exhaust manifold after I was out of warranty . The top cat is part of the manifold so that made the manifold a part of the emissions warranty , I got lucky on that one . Oh and they had to replace to 2 broken exhaust bolts in the head too.

 

[GreatDaneHummer]

So with mine being a 2007 should I stop by the (horrible) dealer or go to my local muffler shop?

 

[alrock]

If there's a chance to fix it under warranty, you should check with the dealer. But any work you pay for, you'll obviously get a much better deal locally.

 

[CaseyS]

My 06 did not throw any codes without the rear cat.

 

[GreatDaneHummer]

Would it still pass emissions?

 

[4speedfunk]

Emissions...what's dat?
[emoji1]

 

[CaseyS]

As long as its welded good, it will pass the emissions to the muffler and out the tailpipe.

And even if you change the engine to a diesel, it will still pass the emissions through the same exhaust so you won't have to redo anything.

Time to move to a red state.

 

[GreatDaneHummer]

I am putting together the money now for a SAS and an engine swap to 4BT. I really want to run 37" tires by next year.

 

[Shotgunchuck]

Probably the guts of the cat. Mine did that several years ago. Just cut it out and put a piece of straight pipe. You already have a cat on the manifold. It won't throw any codes with that one gone.

So, mine has a pin-hole (rust) & is leaking condensation. I can literally remove this without computer or smog check issues?

Thanks

 

[brash47]

This just made me think of an interesting question. On my 06, is the cat part of the exhaust manifold? And if so, if I have to replace the exhaust manifold, which I have done twice now, is it covered under a new warranty every time it cracks?

Sent from my SM-G955U using Tapatalk