vibrating noise...

[AlmondRocca]

I have an aftermarket muffler, but stock cat. When im in low gears in low rpms, theres this loud annoying rattling sound... like the muffler is loose or something. I took to to they guy that put it on and he said they muffler wasn't loose. So do yall think the stock cat is the problem?

[Silv6]

Re: vibrating noise...

if you have ramps, use them and check and see how close the exhaust is to the body or something else it could contact, might try and shake it alittle(the exhaust). mine does this too and i just need to get the time to fix it.

having the stock cat shouldnt effect anything as long as the exhaust was installed right.

[dmw319]

Re: vibrating noise...

could be many things. i suggest the same as Silv6. check under there and see if any pipes or anything are close to the heat shields or if there is anything you can see visually that might be causing it to vibrate/rattle. shake around the pipes and see if you notice anything too. might just be a loose bolt or something somewhere that needs to be tightened up. also, a good way to see if the cat is whats causing your noise.. is to bang on it a little and see if you hear stuff rattling around.. if you do: time for a new cat.

[WarmMachineME]

Re: vibrating noise...

I had the exact rattling noise problem you're describing, a rattle or buzzing sound in lower gears. I took my bird to the mechanic just yesterday for them to check it out.

They told me today it is in fact the cat. He believes there's a broken ceramic fragment inside rattling around. I'd suggest you start by checking out your cat.

[AlmondRocca]

Re: vibrating noise...

cool. im gonna take a look under the car tommorow. What makes me wonder though is that when i first got the muffler put on, it didnt make that noise... and when i floor it... it REALLLY rattles.

[Ace]

Re: vibrating noise...

Dont forget if your have less that 80K miles or your car is less than 8 years old GM has to replace your cat free of charge. Its the law.

[AlmondRocca]

Re: vibrating noise...

Dont forget if your have less that 80K miles or your car is less than 8 years old GM has to replace your cat free of charge. Its the law.

its a 98 with 112,XXX.....:(

[bah]

Re: vibrating noise...

i have a rattle too, but its in my muffler, so something in there is broken, so i'm just redoing my entire exhaust with a rumbler and catco, slowly but surely i am getting there, i think there is a flowmaster on there now, was on when i bought the car

[Ace]

Re: vibrating noise...

its a 98 with 112,XXX.....:(

Damn just missed.

[Bonemaro]

Re: vibrating noise...

I had the exact rattling noise problem you're describing, a rattle or buzzing sound in lower gears. I took my bird to the mechanic just yesterday for them to check it out.

They told me today it is in fact the cat. He believes there's a broken ceramic fragment inside rattling around. I'd suggest you start by checking out your cat.

The same happened to me too. Eventually. a large chunk of ceramics broke off and completely blocked the exhaust. The car wouldn't rev past 2000 RPM and I could only use first gear, as it wasn't enough engine speed to shirt.

On a funny note, the mechanic that was looking at it told me it was the clutch going out. I told him, :bs: , a bad clutch wouldn't make it not rev past 2K. He said, "sure it will; it's slipping." I said, "Slipping would cause it to tach way up without moving." He then said, "Who's the mechanic here?" to which I answer, "I'm wondering that myself."

[Scott90]

Re: vibrating noise...

well since your going to be in the market now for a cat, you should just start looking for a hi-flow cat while your at it.

[AlmondRocca]

Re: vibrating noise...

that would be my best bet! Do yall know any good brands? or a good place to get one? TIA

[WarmMachineME]

Re: vibrating noise...

As others kindly pointed out to me not long ago, a fine Magnaflow hi-flow cat can be found on eBay for ~$50-$60.

Otherwise, the distributors listed in the sticky up top sell them, particularly Summitracing, but it's the same cat essentially as on eBay, so...

[Fireball27]

Re: vibrating noise...

Hmm.. maybe i should check my cat out as well...

[00FlowCamaro]

Re: vibrating noise...

See, I still have the noise I was mentioning in my thread, but i had a gotten a couple suggestoins like exhaust leak or a backpressure problem. Still havent figured it out. So it could be one of many things ><