funny noise on 20v turbo s2, s4 , s6 engines

100turbo c · 20-05-09, 04:44 PM

hi my s4 aan has a funny noise like a wrring noise , it sounds like a turbine on a plane spinning , it does it between 2 and 3500 rpm and is a lot louder from cold when its warm you can barely here it, its not the turbo itself as its always done it and i ve just rebuilt it and got the balance really low on it , but it comes from the turbo area, i have a theory tht it might be a slight crack in the turbine housing which creates the sound and then when warm seals, however i a m only guessing , i would just like to know if anyone else with a 20 v turbo is hearing this on theres, any advice would be interestring to know

burny · 20-05-09, 05:25 PM

a friend of mine who worked for Garrett told me it is not the turbo itself, but could be a part closed to the turbo coming into resonance

SteveT63 · 20-05-09, 08:18 PM

I have the same identical thing on my S4AAN and thought the a
same as you, but having had a chat with the 5pot 20vT engine meister Mr BW2309, we now think it could be a boost (not a Cadburys one, they are slightly rippled with a flat underside!) leak from the back of the engine on a VAC pipe???.

john johnson · 20-05-09, 08:26 PM

and i bet you've munched a few of them too

PeterB · 20-05-09, 08:33 PM

Could it be a noisy Viscous fan coupling?

quattrokid · 20-05-09, 09:18 PM

my S4 sounds like a big hoover from standing start acceleration, or to put it sucking through a straw but obviously louder. A turbine spooling up sounds like a good comparison.

I wonder if my engine MOT failure is a result of a boost leak? (high hydro carbon emissions) seems to not pick up as it should acceleration wise, kick down seems hesitant to activate so it feels like overtaking in top gear instead of droping down a cog, have to push hard and quickly to get it to drop down.

100turbo c · 20-05-09, 09:40 PM

hmm , intersting i will get to the bottom of it, not tht its a problem , but things like this really irritate me

SteveT63 · 20-05-09, 09:40 PM

Rich, its identical on mine, Hoover with your hand over the end, or something else that doesnt quite cover the end of the pipe!!

100turbo c · 20-05-09, 09:44 PM

yep, hoover good comparison , more turbo charged hoover sound!

quattrokid · 20-05-09, 09:44 PM

Eltee popped over to the car for me today, so he is going to return and vag com it, see if any codes comes up.
at least that will give me a clue if a sensor is on the way out.

dont know why but its the last of my problems at the mo.

20-05-09, 08:18 PM	#3
SteveT63 Senior Member Classic Audi Club Member Join Date: Sep 2008 Posts: 3,045	I have the same identical thing on my S4AAN and thought the a same as you, but having had a chat with the 5pot 20vT engine meister Mr BW2309, we now think it could be a boost (not a Cadburys one, they are slightly rippled with a flat underside!) leak from the back of the engine on a VAC pipe???. __________________ Peace...........through superior acceleration! T85 1985 90quattro I5 20vT T81 1983 80 Sport Red T81 1983 80 Sport Silver

20-05-09, 08:26 PM	#4
john johnson Moderator of sausages Classic Audi Club Member Join Date: Sep 2008 Location: sheffield Posts: 13,331	and i bet you've munched a few of them too __________________ Mr OCD http://s159.photobucket.com/albums/t144/jsquatts/ Daily rs4 b7 with buckets that play havoc with my piles And if you are reading this as James may would say ' you're a cock '

20-05-09, 09:18 PM	#6
quattrokid 4 ring whore! Classic Audi Club Member Join Date: Nov 2007 Location: Ayrshire Posts: 9,654	my S4 sounds like a big hoover from standing start acceleration, or to put it sucking through a straw but obviously louder. A turbine spooling up sounds like a good comparison. I wonder if my engine MOT failure is a result of a boost leak? (high hydro carbon emissions) seems to not pick up as it should acceleration wise, kick down seems hesitant to activate so it feels like overtaking in top gear instead of droping down a cog, have to push hard and quickly to get it to drop down. __________________ RS4 B5 (wife's / ours now ) S3 8L Imola Yellow S3 8L Nogaro blue UrWR SOLD UrS4 saloon (SOLD again) S4 Cabrio (SOLD) A4 cabrio 2.5 V6tdi (SOLD) 80 cabrio 2.6 V6 SOLD 90 quattro 10v SOLD 100 2.2e SOLD FOUNDING MEMBER the 200,000 Plus miles Club

20-05-09, 09:40 PM	#8
SteveT63 Senior Member Classic Audi Club Member Join Date: Sep 2008 Posts: 3,045	Rich, its identical on mine, Hoover with your hand over the end, or something else that doesnt quite cover the end of the pipe!! __________________ Peace...........through superior acceleration! T85 1985 90quattro I5 20vT T81 1983 80 Sport Red T81 1983 80 Sport Silver

20-05-09, 09:44 PM	#10
quattrokid 4 ring whore! Classic Audi Club Member Join Date: Nov 2007 Location: Ayrshire Posts: 9,654	Eltee popped over to the car for me today, so he is going to return and vag com it, see if any codes comes up. at least that will give me a clue if a sensor is on the way out. dont know why but its the last of my problems at the mo. __________________ RS4 B5 (wife's / ours now ) S3 8L Imola Yellow S3 8L Nogaro blue UrWR SOLD UrS4 saloon (SOLD again) S4 Cabrio (SOLD) A4 cabrio 2.5 V6tdi (SOLD) 80 cabrio 2.6 V6 SOLD 90 quattro 10v SOLD 100 2.2e SOLD FOUNDING MEMBER the 200,000 Plus miles Club

20-05-09, 05:25 PM	#2
burny Grown up member Join Date: May 2008 Location: France Posts: 94	a friend of mine who worked for Garrett told me it is not the turbo itself, but could be a part closed to the turbo coming into resonance

20-05-09, 08:33 PM	#5
PeterB You absolute shower! Classic Audi Club Member Join Date: Jul 2007 Location: The Chester Posts: 1,444	Could it be a noisy Viscous fan coupling?

20-05-09, 09:40 PM	#7
100turbo c Grown up member Join Date: Feb 2008 Location: hampshire in new milton Posts: 350	hmm , intersting i will get to the bottom of it, not tht its a problem , but things like this really irritate me

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