Fixed my odd noise coming on boost

[mcandmar]

Ever since i got the Avant it has made a very odd noise coming on boost, whenever you dial up more than .5 bar boost it makes a metallic sounding chah chah chah noise. Always sounded like the right frequency for the waste gate to me but never figured out why.

Had another look at it today for signs of gaskets leaking on the manifold and noticed this little arrow on the wastegate flex hose pointing towards the waste gate. Intrigued by this i dug out a spare and low and behold the little arrow is an airflow direction, no wonder i was hearing wastegate noise the damn pipes the wrong way around in the car

3 hours later after rounding off a few nuts i have it swapped around, and no more strange noises on boost. Time will tell if this is why the car never felt as strong top end as others i have driven.

Worth noting all the same, the pipe will fit in either way around, and unless you ever had a need to remove the link pipe you would never know if its wrong. Pure chance i happened to spot that little arrow

[S2central.net]

Thats one to remember.

[prj]

I think I got the same issue, will check tomorrow.
Thanks so much.

[Tonks4x4]

Me too on one of mine, will remember to check that. Good find that man!!!

[newsh]

I've seen one like this recently, you can also tell by the discolouration as the exhaust gas goes down behind the liner and heats up the flexy more than it should.

[Big Lee M]

Great find fella this should be a sticky so no one has this problem agian.

[UrS4boy]

Good find. In *fact* IF you look in the AAN workshop manual you will find this (Figure 4 page 26-5):



NOW I have to go check mine.

[UrS4boy]

Dear Mr. McAndmar, I have taken the liberty of using your photos in a consolidated post on my home forum so others can fix their's properly (if it has been installed in correctly). Hope you approve:

http://forums.quattroworld.com/s4s6/msgs/116238.phtml

[macspring]

Macanmar,

Good one !

Must check the silver car.

Kind regards.

[Billman]

Nice find man. Must check it out on mine also!

[quattro84]

Dual liner flexi's can reduce noise up to 5dB.
Found that out in a test cell facility after acoustic measurements showing that the dual wall flexi was welded flipped around between flanges...

[als2]

another one going for a check, never could find that noise! And your right, always sounded like the wastegate!!
Heres hoping my arrows the wrong way round and itl sort it!!!

PS. does it effect the drive? Boost? at all?

All the best

AL

[als2]

Buuggger! Mines pointing the right way!
Back to the drawing board...........

[s2_wot]

Nice observation Mark, I must check the 6 to see if it's ever been off.

[macspring]

Good one !

Must check the silver car.

Kind regards.

Mine is correct. Presumably never been touched, so if so, the arrow is visible at the 12 noon position on the corrugated pipe and should be easily seen by just looking closely for it.

HTH others.