High pitch engine noise under load

[fonyod24]

Hi
On my Volvo XC90 D5 Momentum 2016 (85.000 miles on the clock) I have developed a high pitch noise from the engine area which comes on only under load/ during acceleration (at about 2500-3000 rpm) and then disappears again at higher revs.
It is more pronounced uphill and when the car is fully loaded.
I never seem to get it when the car is cold.
It started about 9 months ago and is slowly getting worse.
I originally thought it might be from the Turbo system and brought it to Volvo but they said they could not find anything wrong with it but they also said they could not hear the noise.
No smoke. No increased diesel consumption. Power seems to be ok all but that I think I have lost some top end speed (around 20mph on German motorways).
I have an audio file of the noise and will try to find a way to upload it.
Can anybody help?
Many thanks
Chris

[neilgorin]

I have a similar noise that started around the same mileage on a D4 V60.

It sounds like an electrical noise (can't really describe it better) - high pitched and only under hard acceleration in higher RPM, so rarely hear it.

A couple of garages have looked at it with the "we can't find it guv" response. No error codes or anything so I've ignored it for now.

[fonyod24]

thanks neilgorin
I did ignore it for some months now.
My worry is that it gets worse and I do not want to miss a slowly failing turbo.
I will try to upload an audio file or place a link to google drive to share the noise and see what people think.

[rhd443]

Have you checked for any evidence of black spot around the exhaust manifold? This screams to me you have a small leak on the gasket between the block and the manifold.

[fonyod24]

Here is the audio link as promised:
https://drive.google.com/file/d/1SV6...w?usp=drivesdk
The noise is quite subtle and best heard at 5 secs and then again from 7 secs.
Yes, I thought of the exhaust manifold too and cannot find any signs of leakage there.

[fonyod24]

Anybody an idea what it could be?

[Haldex]

The clip “requires permissions from the owner”.. Try uploading to yt.

[KentXRS]

it can be PowerPulse hose, as you have D5 engine

[fonyod24]

Originally Posted by Haldex

The clip “requires permissions from the owner”.. Try uploading to yt.

Sorry.
It should work now.

[Haldex]

To me it sounds more like hissing.. a cracked PP hose possibly?