Turbo whistle or not?

[WhiteGTI]

Upon only WOT, i can hear what can be described as a very high pitched whistle coming from the engine bay. It stays at the same tone regardless of the revs, but only occurs during full throttle. It is pretty faint, but loud enough to hear and distinguish.

There is no whistle until about 3.5-4K revs. So during low down torque the whistle does not occur.

I've only noticed it recently, but because its so quiet it could have been occuring before.

The car is performing as per normal.

Normal? If not, any ideas?

Muchos gracias!  

[RedRobin]

....

Have you changed air intake system recently, Chris?

Or changed to aftermarket engine mounts?

[WhiteGTI]

To be honest, I first noticed it after I took my Carbonio/engine cover off a few weeks ago.

So i figured that it was a slight air leak where where the airbox connects down to the throttle body or something.

But last weekend I took the engine cover off again to reposition it incase there was an air leak, and then put the Carbonio back on, but still the whistle is there!!

hmmmmm......

[RedRobin]

....

I'm just thinking aloud here and you already know I'm not an expert on car mechanicals, but..........

It's possible that the sound was there all the time - The brain easily shuts off constant sounds - But you became aware of it when you removed the engine cover. When you refitted things your brain was then on full alert for the sound and so you homed in on it.

Methinks that if it was a leak, you might feel it via the reduction in performance even if only slight. The other way to check for leak effects is logging (I think!).
 

[WhiteGTI]

^^ True yes!

I may see if the legend that is DomT is around one evening soon to do a quick log for me! 

[RedRobin]

....

As ever, it's a process of elimination and always thinking positive - You'll always 'win' that way.

Do let us know what unfolds.

[bacillus]

I know it's happened to Gaz with his S3 but is the rubber ring still on the plastic piping that fits into the airbox at the maf side? In Gaz's case it was "lost" when he removed his air box.

[bacillus]

Here's a pic of the O ring I refer to courtesy of SteveP.

[WhiteGTI]

You may have hit the nail on the head there Bacillus....

When I took the engine cover off that O ring fell off and it wouldn't reposition correctly - I think because the engine bay was hot and it's shape became deformed. Anyway,it was a tight fit but I managed to reconnect the piping around the O ring. I did have a suspiscion that the noise was to do with that.

But since I've refitted the engine cover I positioned the O ring perfectly and because the engine was cold it fitted well. But alas, the noise is still there!!

So what does turbo whistle sound like? Does it change with revs?

Thanks,
Chris.  

[Phil Mcavity]

^^ True yes!

 The legend that is DomT is around one evening soon to do a quick log for me! 

make sure he wipes up after he's finished

[Poppa Dom]

Chris, am about tonight if you want to do some logging for piece of mind. By the timing of when you have heard the whistle and how it has coincided with your carbonio I reckon that there is a good chance that it is down to a poor seal on that o-ring. The negative pressure produced is probably pulling in air around the seal creating the noise. Give us a buzz this evening if need be.

[WhiteGTI]

No problem at all with the car!

According to the logs, it is running sweet as a nut! No/very low correction factors, good intake temps and requested / actual boost being met.

Thanks all.
Chris. 

[MitchGTI]

You worry to much! I told you it was fine mine sounds exactly the same! : p havin secret meet ups without me again lads?! Lol

[xxx_mojo_xxx]

For what its worth, my car kind of whistles when acellerating hard, only briefly at a particular rev range...I think its part and parcel of how the engine sounds.

[WhiteGTI]

You worry to much! I told you it was fine mine sounds exactly the same! : p havin secret meet ups without me again lads?! Lol

LOL!!!!!!

True you did say that! I just wanted to be sure, because the noise was still there even after I refitted the O Ring and Carbonio.

But it was also good to log the car as the temperature is getting lower - as the last time we logged the car it was in the middle of the summer!

Nono, not secret meet-ups, another last minute decision. We should organise something soon though mate. Are you coming to that Reading VAG meet in a couple weeks, and also the Rolling Road in Chobham in November??