Noise under acceleration

[PenguinGTI]

Hi guys, looking for some advice about the car:

The problem

Some times when I am accelerating the car makes a funny sound. I don't quite know the word to describe it but it's almost like a squeak. It occurs only when I throttle.To narrow it down I've been keeping my foot on the throttle at various revs and the noise occurs just before the whistle of the turbo spooling.

At first I thought it was maybe the throttle but I can accelerate without the noise occuring. I don't know if it is the turbo or not but it definitely happens immediately preceding the turbo whistle.

Now my immediate concern is that the turbo might be going. I'm not experienced mechanically so I don't really know but my mind has jumped to the worse.
I woul expect however that if the turbo was going then I would experience power loss and also that the noise would happen every time. The noise is intermittent and sometimes I can go a few days without the noise happening.
Here are my questions:

Has anyone else had this noise?
Is this a sign that the turbo is going?
Is it perhas a belt or something that just needs lubricated?s
My car has now covered 40k miles

*EDIT I've been reading some on the internet who say that the turbo going usually produces smoke. There is NO smoke coming out my car if this helps with any advice.

[Buck]

I can only share my experience of when the turbo on my Audi was going and it sounds more 'dry' and rattley if that makes sense?

Certainly wasn't squeaky.

[PenguinGTI]

Yeah it's definitely not rattley.

The noise itself I woud say is more akin to a belt or pulley squeak but it only happens when the turbo is about to spool.

[The Doc]

Could be anything - what boost pressure are you running? bhp? Mods?

[GolfTi]

It's not the faint hissing sound is it?
On acceleration - 2 - 3 k lasts for less than half a sec.

Normal if it is.

[WILLS]

i get a hissing/metallic rattle between 2  - 3k i've been told this is normal

[PenguinGTI]

Doc, No idea what boost I'm running. Horsepower is around 260 odd with a stage 1 map.

There is definitely no power loss so I'm not entirely convinced it is the turbo.

I do know the hiss you are describing which if I am correct is the standard noise of the turbo spooling up.

The sound I sometimes get is altogether more like a squeal. It very much sounds like a belt squeal and I would assume it to be such were it not for it only occurring immediately before the turbo spools.

That having been said, drove home tonight and it didn't make the noise at all... just one of those typical niggles that only does it sometimes.   

[RickS]

Yeah it's definitely not rattley.

The noise itself I woud say is more akin to a belt or pulley squeak but it only happens when the turbo is about to spool.

Penguin, you mention the "whistle of the turbo spooling". I've had several cars with turbos and none of them whistled, I don't think you should be able to hear the turbo from inside the car if it's working correctly, unless you've done a mod to make it audible.
I certainly can't hear it on mine.

[Snoopy]

Does it also make it if:
Your in neutral. You rev the car to ~3K then take your foot off the pedal?

[Exonian]

Any chance of recording the noise on your phone and uploading it so we can hear it? Would be easier to diganose that way.
I'll assume you don't have any uprated engine mounts or any other mods (dump valve etc)?