A little help? getting a rattling noise

[eyuras]

So, I recently joined the club and bought a v6 firebird, its a 2000 and in very good condition.. but the only thing I am having problems with is this noise. I have checked all of the exhaust (a flowmaster American thunder), and the heat shield seems to be tight and in place, I also replaced the hangers which stopped the noise completely for about a week, now if I push the passenger side exhaust tip in any direction the noise stops (same for the drivers side one but it requires more force to do so) the noise does go away after the engine warms up but does come back when the engine is revved.

Does anyone have any ideas of what is causing the noise?

Video: http://www.youtube.com/watch?v=dEHYPZzTb8A

any help would be greatly appriciated!

[Meatyshells]

Re: A little help? getting a rattling noise

maybe there's something stuck in your muffler?

[whitdog54]

Re: A little help? getting a rattling noise

Your CAT maybe. I heard people having their stock cats rattle, I guess because there is 2 layers of metal and over time they get loose and bang against eachother. I think heard about this on this site, so maybe someone can chime in. Are you positive its coming from the exhaust?

[eyuras]

Re: A little help? getting a rattling noise

Thanks for the reply's!
I think it may actually now be from the exhaust rattling against the car itself (there seem to be some very tight spots where if the exhaust were to move at all it would hit the frame)
I am going to loosely attach some left over dynomat to those places and see if it prevents it from rattling.

[Mark42]

Re: A little help? getting a rattling noise

Cat systems have heat shields that can vibrate and make noise as they age (read rust off). This is a very common condition, especially on an older exhaust system. If possible, reach under the cold car and bang the exhaust pipes with your hand and listen for a rattle. If it is a heat shield, depending on the design, some can be re-attached using stainless band clamps or drilling holes and using stainless sheet metal screws. If you don't use stainless hardware, you will be fixing it again in a few months.

If its not a heat shield, check for damage that may have bent pipes or hangers and let the pipes rattle against the under body.

I am going to loosely attach some left over dynomat to those places and see if it prevents it from rattling.

This is not such a good idea, because the exhaust can cause the dynomat to burn. Best to fix the cause of the pipe being out of its normal location.

Good luck and post back what you find/fixed.

[eyuras]

Re: A little help? getting a rattling noise

Thanks Mark,
The heat shield seems to be in fairly good condition, I wasn't able to make it rattle or move at all (its on very tight to the under body)

Banging on the exhaust only made.. well a banging noise at it bumped up against the body

I removed all the dynomat after my test (It didnt help me find the source of the noise at all)

I am starting to think the hangers I bought were just not any good (they have started to stretch by about a good 1/2 inch)

Passengers side, seems fine


Drivers side is very stretched looking

(ignore the second hanger on that part its off now i had just been testing if the bar was touching the exhaust and it was :cry:!)
(if i physically move the exhaust up a little while its making the rattle noise it stops) (obviously not using my hands)

I am starting to think who ever installed this exhaust must have had no clue.. (not unlike me)

[Mark42]

Re: A little help? getting a rattling noise

If you think the donut has stretched out, pick up a couple of new ones and see what you can fit in that is a better fit.

You can also try putting a stainless band clamp around the old donut and tighten it up to see if shorting it gets rid of the rattle.

From watching the video, (great idea, btw) it looks to me like the passenger side pipe is too close to the car on the far right side of the pipe.

[insaneABOT]

Re: A little help? getting a rattling noise

Try to press down on the passenger side exhaust tip. If the noise goes away then you need to check to see if the weld on the pipe that comes over the other pipe is broken.

[jarashto]

Re: A little help? getting a rattling noise

It could also be your "Y" pipe itself. I'm not for sure about previous models, but the 98-02's have a dual layer y pipe. Same thing happend to me and I had my exhaust shop just weld through both layers to attach them again. If the noise goes away when the car is warm then that would explain it. The inner layer is expanding to cause less of the noise.