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buzzing flex section on stock downpipe

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#1
I thought my custom exhaust suffered a failed resonator due to a loud ringing/buzz around 3100 rpm, but I can't find any indication after taking it all apart.
I did notice that even with stock exhaust I can kinda hear the sound (though much less due to less acoustic vibration on the stock exhaust) and it seems to come from the downpipe/flex area. Has anyone ever experienced this? It's like the mesh-y part is vibrating, and I'm hesitant to bother taking it in to the dealer but I am not sure what else to do. Due to my location I cannot swap to an aftermarket downpipe. The flex section is much more flex-y than I expected, too.
 

CanadianGuy

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#2
Well the flexi bit in the downpipe is the catalytic which could be loose but have only seen that in high mileage. If under warranty have it replaced.

Is the sound like a ballon loosing air via a small hole? Reason I say this is maybe it’s not exhaust but the symposer diaphragm is torn. Can sound like a kazoo.

Good luck
 
OP
Clit_Beastwood
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Thread Starter #3
Well the flexi bit in the downpipe is the catalytic which could be loose but have only seen that in high mileage. If under warranty have it replaced.

Is the sound like a ballon loosing air via a small hole? Reason I say this is maybe it’s not exhaust but the symposer diaphragm is torn. Can sound like a kazoo.

Good luck
It's definitely a metal ringing sound - I thought one of my resonators had internally separated but after swapping back to stock I still get a little buzzing around that rpm, though a lot less as the stock system has very little resonance at that rpm.
 

CanadianGuy

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#4
It's definitely a metal ringing sound - I thought one of my resonators had internally separated but after swapping back to stock I still get a little buzzing around that rpm, though a lot less as the stock system has very little resonance at that rpm.
In my experience it is usually a loose heat shield 🛡 somewhere.
 

D1JL

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#5
The flex pipe issolates the exhaust system from the engine.
The steel mesh you see is the reinforcement portion of the flex pipe.
The internal portion is not stranded.
Because this flex pipe is close to the exhaust header it can get very hot.
It has been my experience that when it starts making noise it is usually because of an internal crack or leak.

In my previous life I have run across this many times.
Of course this portion of pipe should and can be replaced.
However, because on many cars, it is located before the cat and part of the same pipe, in many states it becomes a smog violation.
The only legal alternative is to replace the complete down pipe.

I am not the smog police (any longer) so, I don't care what you do. ;)
 
OP
Clit_Beastwood
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Thread Starter #6
The flex pipe issolates the exhaust system from the engine.
The steel mesh you see is the reinforcement portion of the flex pipe.
The internal portion is not stranded.
Because this flex pipe is close to the exhaust header it can get very hot.
It has been my experience that when it starts making noise it is usually because of an internal crack or leak.

In my previous life I have run across this many times.
Of course this portion of pipe should and can be replaced.
However, because on many cars, it is located before the cat and part of the same pipe, in many states it becomes a smog violation.
The only legal alternative is to replace the complete down pipe.

I am not the smog police (any longer) so, I don't care what you do. ;)
Oh I want to keep it on the up and up, I've been fined for catless before years ago and learned my le$$on.
 
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