Buzzy tinny rattle @ 3000 rpm

[froggy47]

Started a couple of weeks ago, went under the car with rubber mallet & started tapping.

Right side exhaust about 4 inch back from the header flange the exhaust pipe has some curves/waves/crimps in it (for lack of a better description) I can tap on it & get a tinny/rattle like 2 pieces of metal hitting. Is there anything in there or is it straight pipe back to the cats?

I can replicate the buzzy/tinny/rattle every time in 1st & 2nd at 3k rpm.

THX

[ToolGuy]

I had similar. It turned out to be a broken weld right at the H pipe, the top weld, so I could not see it from below. Sounded like someone was rattling car keys and I could hear it every time.

Replaced the pipe with an X pipe and it was gone. That's when I could see the broken weld too.

Just throwing that out there...

[froggy47]

Thanks, next time I have the car up I will check further.

:)

[LLC5]

Originally Posted by froggy47

Started a couple of weeks ago, went under the car with rubber mallet & started tapping.

Right side exhaust about 4 inch back from the header flange the exhaust pipe has some curves/waves/crimps in it (for lack of a better description) I can tap on it & get a tinny/rattle like 2 pieces of metal hitting. Is there anything in there or is it straight pipe back to the cats?

I can replicate the buzzy/tinny/rattle every time in 1st & 2nd at 3k rpm.

THX

I would imagine that it is double wall construction. If it is possible, try putting some dimples in the pipe at the point of the rattle if you can, and see if it goes away. Honda actually had us do this to certain models of the "B" pipe with a large C clamp, and it worked great. Just be carefull not to damage anything. Good luck with it.

[froggy47]

Originally Posted by LLC5

I would imagine that it is double wall construction. If it is possible, try putting some dimples in the pipe at the point of the rattle if you can, and see if it goes away. Honda actually had us do this to certain models of the "B" pipe with a large C clamp, and it worked great. Just be carefull not to damage anything. Good luck with it.

Interesting, so it would be to contain some heat?

[LLC5]

Originally Posted by froggy47

Interesting, so it would be to contain some heat?

To help heat the cats as fast as possible. A lot of Honda's have their catalytic conveters built into the exhaust manifolds for the same reason.

[froggy47]

I have gone over this again & I think it is actually the matrix in the cat that has started to break loose. What do you think? I have never had one apart, but have actually seen some bits of cat material that blow out the exhaust. Not on my car, but I have seen it on videos where it just disentigrates & blows out the exhaust.


:)

[LLC5]

Originally Posted by froggy47

I have gone over this again & I think it is actually the matrix in the cat that has started to break loose. What do you think? I have never had one apart, but have actually seen some bits of cat material that blow out the exhaust. Not on my car, but I have seen it on videos where it just disentigrates & blows out the exhaust.


:)

It's not impossible, and a cat that is falling apart internally would make that kind of noise. I would be more suspect of heat shields though. This noise could also be your shifter buzz, maybe?

[froggy47]

Originally Posted by LLC5

It's not impossible, and a cat that is falling apart internally would make that kind of noise. I would be more suspect of heat shields though. This noise could also be your shifter buzz, maybe?

I believe it's two different noises, just showing up at the same time. There is the heat shielding, yeah, it seems ok when I go tapping around but it's pretty tight, maybe I'll shove some header wrap up there & see if it goes away.

:)

[ToolGuy]

My car had both of its cats replaced under GM warrenty when my car was inspected my a GM technician. The tech said he saw some cracks, I guess at the welds. However, there was no noises coming form it. So in my case, I knew it was not the cats.

My bets are cracked H pipe welds. Many have had this issue and you will go nuts trying to diagnosis it. Drop the pipe and inspect the top welds.