Bought this yesterday, no problems on test drive, pulled hard in all the gears. On the way home from dropping of seller, warmed up and under hard acceleration, this screeching noise can be heard from the engine bay.

Noise is loud, happens under hard acceleration at first and then normal acceleration, until you keeps the revs low for a while, then it will accelerate normally again without the noise.

There is a dip in power when making the noise. Without the noise it picks up speed very good.

No black smoke.

Any ideas? I'm worried i've bought a dud. I'm hoping it's a pulley, but power is affected so maybe it's the turbo?

Edited 28 March, 201511 yr by Yaris

Dude, that's a quiet whistle at worst, probably a very slight boost leak, don't exaggerate so wildly.

Just hope you don't get a stone caught in rear brakes, that makes a screeching noise.

But as above does sound like a boost leak.

Sent from my Nexus 4 using Tapatalk

It's louder outside of the car, but I never recorded that as there would be too much wind noise. It doesn't sounds like air leaking sounds more mechanical, like a bearing/pulley noise

Check your alternator pulley. You may see some very fine metal filings around that area.

Had a similar issue with mine although I didn't have any loss of power, it got worse and worse until it completely disintegrated and threw the belt off.

If you are experiencing loss of power, then you'll want to follow the advice above and check for boost leaks. It's not uncommon due to the inter cooler pipe work couplers wearing over time allowing the joints to flex.

Check drive belt and pulleys easy to spot if badly worn. Quite easy to replace

It only has to be the slighest tear or pin hole in pipes to lose power and makes sounds

Pipework can work its way loose over time

I have found with a dieing alternator pulley it tends to chatter at idle and sounds loudest when you lift off. Also the aux tensioner tends to vibrate at idle. If it is the pulley then change the belt and tensioner too.

Sent from my Nexus 4 using Tapatalk

I'll have the necessary pipes and pulleys/belts checked next week. Cheers guys. Had a reassuring chat with the seller and i'm confident it's nothing major, the car has simply had a good spanking for the first time in a long time which has flagged up this issue.

Will update the thread once diganosed.

That sounds like what I've got when I accelerate, it's like a whooshing sound on foot down accelerating and I've had the alternator bearing pack in with the fine metal fragments last year so new alternator belt and idle pulley it was.

If's not belt or pulley related as the power is compromised when the noise starts, and when it stops the car starts pulling again.

Booked in for next Friday

Mine does that but only if it's cold n I boot it. When things have warmed up, it's all good. Skoda themselves assured me it's just because it's cold and there is no friction on the alternator belt.that's my issue anyway. Yours could b different but it sounds the same.

If's not belt or pulley related as the power is compromised when the noise starts, and when it stops the car starts pulling again.

Booked in for next Friday

Sounds like belt is slipping to me. If when the noise stops theres power again

Sounds like belt is slipping to me. If when the noise stops theres power again

Why would a slipping aux belt cause a loss in engine power?

Sent from my Nexus 4 using Tapatalk

Why would a slipping aux belt cause a loss in engine power?

Sent from my Nexus 4 using Tapatalk

I was wondering that?

I'm no mechanic but as belts and pulleys are driven by the engine, and not the other way around, a loss in power must mean the fault is with the engine/turbo system.

Edited 4 April, 201511 yr by Yaris

Why would a slipping aux belt cause a loss in engine power?

I misread. Thought it was a charging issue

I believe the problem here is pretty standard with the VW engine turbos. My previous Fabia did this a lot. My Golf used to do this from time to time. 

What I THINK it might be is the VNT 'lagging' slightly or getting stuck and the noise is turbulent air inside the turbo housing.

 

It's hard to remember but I think I fixed it for a while by replacing the 90 degree boost pipe next to the intercooler, but it slowly started to come back. I'm not sure if it was a result of less boost leak causing the boost to build quicker or just the boost leak making the noise itself!

If my new Fabia starts to make this noise (which I really hope it doesn't because it does seem to happen when there is power loss), my plan will be to replace the N75 valve and to clean the VNT like crazy.

Failing that I will trace for boost leaks. 

Other than that it's a real mystery why they do it because I tried a few higher mileage Fabias and they did it, but a lower mileage one does not seem to do this. 

Cheers for your input lads. As long as it's not a problem with the turbo itself.

Garage plugged in a diagnostic machine and took the car out for a good thrash (with me in the passenger seat holding the £6500 Bosch computer) and I watched the expected boost and actual boost displayed in a real time graph, and there weren't any real discrepancies, sometimes with actual boost more than expected.

Garage thinks it's a very small split somewhere and even a smoke test could not find a leak with the car on a ramp, a rolling road would be needed.

It's not the turbo anyway, and basically i've chose to wait until the noise is worse, therefore easier to pinpoint, as opposed to taking apart all pipework related to intake in a bid to find a split/hole somewhere.

They also removed the undertray and inspected the intercooler pipework, no visible problems.

Edited 11 April, 201511 yr by Yaris

So did you find out what this screeching was in the end as that is what mine is doing 

On 19/11/2020 at 23:24, Rhys123 said:

So did you find out what this screeching was in the end as that is what mine is doing 

@Rhys123 did you find the answer as to why yours does it?