Whistling noise under heavy acceleration

[Chriso103]

I have an Audi A6 3.0 TDI Avant C6 2010 year. Just recently, there's been a whistling noise under heavy acceleration. It's not there stationery, so not slipping belt. I suspected a leak in an intercooler pressure hose but removed the hose from the second intercooler to the intake on the engine and that was fine. Others look ok too. There's no loss of power or fault codes. Any ideas on what else it might be would be welcomed.

 

[stefdds]

These noise problems are always fun.... (not). How about a video clip during the concern.
Could be a belt tensioner bearing or a accessory belt bearing.

 

[Chriso103]

I thought that to begin with but ruled it out because it doesn't make the noise when revved hard when stationery.

 

[DrPeter]

Hi there, it does sound like a boost pressure leak, 'somewhere'.

I have seen boost leaks from all sorts of components, hoses, pipes, intercoolers, intake manifolds, etc.
Pro tip: Keep an eye out for things like cracked plastic parts (and others) that look fine.. but under boost pressure they will leak.

Best way to help discover these types of leaks are to close off and lightly pressure the system and listen for the leak. Smoke testers generally do not have the ability to test with any significant pressure to reveal hidden leaks.

If it is not a boost leak, maybe an exhaust leak? But a noise under load on a turbo engine, sounds like boost...
I second the motion for a video!

Hope this helps and let us know what you find

drpeter

 

[SaVAGeSoot]

How old is the PS fluid? (and is the level correct)

 

[Chriso103]

Hi there, it does sound like a boost pressure leak, 'somewhere'.

I have seen boost leaks from all sorts of components, hoses, pipes, intercoolers, intake manifolds, etc.
Pro tip: Keep an eye out for things like cracked plastic parts (and others) that look fine.. but under boost pressure they will leak.

Best way to help discover these types of leaks are to close off and lightly pressure the system and listen for the leak. Smoke testers generally do not have the ability to test with any significant pressure to reveal hidden leaks.

If it is not a boost leak, maybe an exhaust leak? But a noise under load on a turbo engine, sounds like boost...
I second the motion for a video!

Hope this helps and let us know what you find

drpeter

I tried to use my dash cam for a video but there's a lot of road noise drowning out the whistle. It's just about noticeable 2 or 3 times in the first minute of the attached. It occurs whenever I kick down the auto box above 3,000 RPM, then dies away.

I've had the bumper off the car today! Checked all the hoses and they seem to be fine, not perished, still flexible and I've checked under the mesh material covering, despite the fact they've been on since 2010! So, probably something else, like you say plastic or metal or maybe intercoolers themselves. On-going project I fear. How would I 'lightly pressure' the system?

 

[Chriso103]

Hi there, it does sound like a boost pressure leak, 'somewhere'.

I have seen boost leaks from all sorts of components, hoses, pipes, intercoolers, intake manifolds, etc.
Pro tip: Keep an eye out for things like cracked plastic parts (and others) that look fine.. but under boost pressure they will leak.

Best way to help discover these types of leaks are to close off and lightly pressure the system and listen for the leak. Smoke testers generally do not have the ability to test with any significant pressure to reveal hidden leaks.

If it is not a boost leak, maybe an exhaust leak? But a noise under load on a turbo engine, sounds like boost...
I second the motion for a video!

Hope this helps and let us know what you find

drpeter

Sorry , how do I send you the video

 

[Chriso103]

How old is the PS fluid? (and is the level correct)

Sorry, don't think it's PS linked

 

[SaVAGeSoot]

Sorry, don't think it's PS linked

No worries... not my issue.
Answering those two would take seconds, but let's see what you find.

 

[DrPeter]

Hello,

How would I 'lightly pressure' the system?

I would say no more than 1 bar (about 15 psi) of pressure, as most turbo charged systems should be able to handle that amount of pressure.

how do I send you the video

Well you could take a video, save it and then find a video hosting service (like youtube) and upload it there and then post a link to the video in this forum thread. There maybe even videos on how to do all this too?

By the way, do or did you ever have any fault codes like this one?

16683/P0299/000665 - Ross-Tech Wiki

wiki.ross-tech.com

Hope this helps,

drpeter

 

[Chriso103]

Thanks, I'll look into it. When I said how do I lightly pressure the system, I meant how do I go about this, what kit do I need etc.

So far I've had no fault codes showing, well none that have triggered a CEL.

 

[Chriso103]

Hello,



I would say no more than 1 bar (about 15 psi) of pressure, as most turbo charged systems should be able to handle that amount of pressure.



Well you could take a video, save it and then find a video hosting service (like youtube) and upload it there and then post a link to the video in this forum thread. There maybe even videos on how to do all this too?

By the way, do or did you ever have any fault codes like this one?

16683/P0299/000665 - Ross-Tech Wiki

wiki.ross-tech.com

Hope this helps,

drpeter

Thanks, I'll look into it. When I said how do I lightly pressure the system, I meant how do I go about this, what kit do I need etc.

So far I've had no fault codes showing, well none that have triggered a CEL.