Ok, here's the issue, i go an 04, mt, with 24,000mi on it. I put a borla cat back on, rest is stock. When im driving and give it about 1/2 to 3/4 throttle in 2,3,4,5 gear it dose this sligt vibration like an aluminium fan blade just brushing the radiator. It wont do it in neutral at all and usualy not 1 or 6 either. It's not the exhaust hitting the diff, i've already fixed that, and it sounds like its coming from up front. And the other day i went for a cruze, i was blasting around for a while, then tried to make it do it driving normal on the way back home and it wouldnt do it then. Seems more noticeable at first. Any ideas guys? To me it doesnt sound like the cat, or waterpump issue, or marbles in a can issue or any of that, mainly cuz it wont happen at all in neutral. Thanks guys

 

Two thoughts, first might be the heat shield bolt rattling, check them. If you replaced the entire exhaust, up to or including the headers you might be hearing the internals of the engine, ie ports opening up... You start to hear different things when swapping parts that are not oem, this might just be one of them...

 

Maybe you're talking about the "Marbles in a Can" symptom?

 

check the exhaust to the shielding above it.. the main muffler section..

give it a very good tug down..

beers

 

I'm also thinking heat shield on the Cat... I just had that problem. Used some large hose clamps to fix that issue.

 

Yea i know it isnt the marbles in a can, blender, sand in a blender thing...also prolly not internal engine noise...also only replaced from cat-back. I did check some heat shields before whan i was under it, but didnt spend much time cuz they felt tight. I will have to jack it up and check the ones tucked up against the car i suppose. Thats pretty much what it sounds like. And i suppose when it gets warmed up, the expand away from whatever they're hitting right? That makes sence to me...Ok now i gotta get motivated to go jack the thing up lol...I'll let you know what i find after i do it. Thanks for the thoughts guys.

 

They also put heat shields around the gas tank.

 

that is about the rpm that the ssv valve opens - maybe a coincidence .....

 

wow,

that jogged my memory..

if you do not have the last flash get it..

it solve that rattle for me a flash or two ago..

beers

 

Humm i dont know what flash it has honestly, i just picked this on up a little bit ago, this is my second 8, I'll have to see if my code scanner can pull that up to see what i got. Is there any easy way to check the flash i got?

 

Well i finaly got the car up in the air this weekend.I checked everything you guys said, nothing is loose, i was under there just pulling and banging on all the heat shields and everything else, and its all tight.So the only thing left is maby the flash is old. I still gotta check that. Otherwise i guess its gotta go in.

 

Ok guys, took the car to the dealer yesterday, they basicaly tokd me they have no idea. Yhe only useful piece of info they gave me is that they realized that it did it at about 7100rpm as well, So any ideas now? Also learned that it has the latest flash and ruled out exhaust noise, the ssv valves since it does it twice, and you can hear the high rpm rattle in the car when its in neutral, where as the 3500 one it was only heard in gear. Soooo is there a possibility that there is a pully going bad or something like that? Anyone got any other ideas? I appreciate the help guys, the damm thing's starting to **** me off