2009 S3 Exhaust blowing

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shandyhaggis

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Afternoon all

this might be a common issue, please let me know if so.

I bought my 2009 S3 from Audi a couple of months ago. It has an exhaust blowing noise that has got worse. I assumed at first it was just a sporty exhaust note, but its def not right.

Popped it on ramps today at a local garage and it seems that the middle section of the exhaust (with the cat) has a tube from the cat that then splits into 2. 1 section goes into a box the other section bypasses the box before joining together again into a single pipe. The bypass section has a gap in the exhaust system filled with a rubber flex hose (about 3 inches). Its this bit thats blowing.

Any ideas as to what its for ? or if its repairable? Id hate to think Id need a new middle section exhaust with cat etc... Seems a stupid design.

The cars still under warranty but I suspect the exhaust system typically isnt covered!

The guy at the garage doesnt know what its for either and has suggested just cutting the flex tube out and welding a new pipe in its place. Seems a bit drastic but then if the flex tube serves no real purpose then why not!

Any thoughts would be appreciated.

thanks
Andrew
 
i think its to do with sound regulations in some places the box is a resonator, when you full throttle it opens both pipes, the fumes then go thru the less restrictive non resonated part, more power, more noise.

but again i might of just made that up lmao so confirmation from someone who knows something lol.
 
Thanks I thought it would be something to do with the sound / valve of some sort.

Can anyone confirm? Do I need it?

thanks
Andrew
 
There is an Eu regulation flap in the left-hand side pipe... Only opens at something like 3k rpm...

Perfect excuse to buy a BCS turboback exhaust imo... Wish mine would start blowing ha...
 
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thanks for that:)

its on the drivers side pipe so I guess thats LHS when you look at the car.

Ill take it to Audi next week and let them have a look at it. Im hoping there is a simple fix otherwise it could be expensive :)
 
Hi...
This is a common fault on the oem system, but don't worry its a simple fix that will cost you around £50.00 (Audi full front assembly £1k)



All that is required is for the flexible bellows section to be cut out and a new section welding in its place. We would be happy to help if you can't find anyone local to do the repair. Cheers
Nige
 
Brill thanks for that

any idea what its for? Does it serve any purpose?

I was quoted around 300 to have it cut out and a section added. It was a spur of the moment quote but I guess its to cover taking the exhaust off / welding and refitting.

Ive spoken to 6 or 7 people in audi and non are prepared to tell me anything with out seeing the car, Ive booked it in for a couple of weeks time. I suspected it was a common fault it just screams of being a weakness waiting to fail.

Thanks, whereabouts are you Nige?
 
Hey bud
The flexible bellows section is to accomodate the expansion in the thinner material in the resonator silencer end plates next to it. If the resonator silencer was not in the system then the bellows wouldn't be required. This is in no way connected to the flexible transverse torque de coupler in the down pipe.
The weakness is in the material which is only 0.4mm thick this is further work hardened by the welding process which compromises its original strength and makes it an inevitable failure - the mesh coat is to protect it from stone strikes - such is its flimsyness.
In terms of the repair, the down pipe needs to be un coupled from the rest of the exhaust - again a simple excersise as it is on its own remote connector not a slip joint that would require the rear section to be pulled off the down pipe. Next the front pipe mount (just visible on the right) needs to be un bolted... Once this has been done the down pipe will flop down on the flexible joint low enough to be able to cut out the offending part and create enough clearance to put the new section into place and weld up (including getting over the top of it to complete the weld...
We are in the North West in Haydock...
Hope this helps bud - don't get stung
Cheers
Nige
BCS Automotive Limited
 
Are these common Nige? Might be the excuse I need to tell the wife for coming to see you if mine goes.
 
audi upgrades
To be honest Kev - the majority of DP's fail either on the front flex or the bellows... it seems to be an inevitabilty on this design :sign_unfair:
Cheers
Nige
 
Very I have had to had mine done but bcs have sorted something else for me now
 
thanks Nige

Im assuming then that removing the flexible bit with a rigid bit doesn't cause any other issue. Is there enough flex elsewhere to make up for the expansion?

Also am I right in thinking removing the bellow wont improve performance..
thanks

A
 
Ideally the replacement section should be a flex preferably longer than the OEM one, to achieve a permanent solution - however, a ridgid replacement would serve a s a good cheap fix and should give a minimum of 5 years worth of regular use...
No performance gain to be had by swapping the fex for a ridgid section.
Cheers
Nige
 
BCS Nige said:
Ideally the replacement section should be a flex preferably longer than the OEM one, to achieve a permanent solution - however, a ridgid replacement would serve a s a good cheap fix and should give a minimum of 5 years worth of regular use...
No performance gain to be had by swapping the fex for a ridgid section.
Cheers
Nige
Click to expand...


Ill have a little dig around to see if I can find a flex pipe option that would work. If not then I'll give you a call to arrange for the section to be repaired.

If I do find something Ill let you know what it is and if it works!

thanks again

Andrew
 
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