Strange high pitched whistle sound upon warmed up engine.

[TLondon]

Hi - just joined to see if anyone can help me with this strange engine noise->

Hi all, new joiner here to the forum. Can anyone help with this engine issue? Happens after 30 mins of driving without fail, stops if i tap the accelerator and when it starts the idling revs become very erratic.

I’ve just spent £200 at a local garage trying to fix it, but it remains. They replaced some pipes that had erroded but its not fixed it. Back into there after the weekend.

Does anyone recognise it?

[Clarkj93]

Sounds almost like some belts about to die.... but weird it only happens when warmed up? A fan belt is under a 10er so could try replacing just to see if it makes any difference, probably what id try first but I'm not totally sure sorry pal. Someone more technical will have a pop soon im sure 

[TLondon]

Thanks for the response - hopefully someone else can chip in also. I have read it might be the diverter valve also.

[TLondon]

Having checked looks like this thread identical ->

https://www.mk5golfgti.co.uk/forum/index.php/topic,51453.msg587574.html#msg587574

Is the PCV the same as the diverter valve?

[Clarkj93]

No the pcv valve and diverter valve are very different things. Neither are very expensive however if either are the issue.

[TLondon]

Here is the work I had carried out this week.