Fabia VRS turbo screech sound (cold engine)

[mauri]

Good evening everybody and thank you in advance.

I had a crack on exaust manifold of my old (remapped) Fabia VRS, so the original turbo unit (Borg), has been replaced with a regenerated one (Garrett), already a few months ago.

Since the beginning, when the engine is cold (I mean the car stopped for several hours) the new turbo unit makes an high pitched strident cry, in the range of 1500-1700 rpm.

This "terrifying sound" takes place if you short shifting with gears (reaching 1500 slowly). On the opposite, reving a bit the gears (1st gear), that sound is so short it's diffcult to hear.

I suspect this "screech", which totally disappears when engine is "just out of cold", has something to do with variable geometry external blades, which doesn't change their inclination unless the gases (stream) has some power and the unit temperature is "ambient".

Do anyone confirms, or-and has a more technical explaination?

The car already made some 3000 miles with the "new" turbocharger, the power looks as it was with the original Borg turbocharger, if not more, as well as acceleration.

Can I keep this "effect" because isn't really dangerous, or it's better I require a replacement?

(The turbocharger unit is under warranty, but work to replace will be at my expense)

 

 

[jamwatn]

I'd contact the supplier who sold you it. I'm pretty sure it shouldn't screech. At worst there should be a mild whistle!

[jamwatn]

Ps:

Check the turbo has a decent oil supply first. You haven't managed to bend the feed pipe slightly have you?

[mauri]

Thank You for comments.

I'll contact the refurbished turbocharger supply as soon as they come back from holyday.

Concerning the turbo replacement, I don't think mistakes have took place, because the work has been performed by a professional with a great knowdledge ad experience, who follows VW training courses.

Moreover, I think a poor lubrication should produce problems at higher rpm and long runs, rather for a few seconds ad start (from cold). Anyway, I take your suggestion checking the pipe.

The problem worries ad intrigues me at the same time, I'd like to understand what's the reason of one short high pitched strident cry, only at cold engine.

[AshVrs]

I wouldn't keep driving it mate until you know what the cause of your noise is, last thing you want is bits of turbo in your intercooler and boost pipes if the turbo fails in dramatic fashion.

Can you upload a sound clip?

Are you mechanically minded enough to take the turbo intake pipe off and have a look at the compressor wheel?

Also is it a reputable company you bought the reconditioned turbo off?

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