Technical What is this whining noise?

[DoctorPetrol]

Hey everyone! Happy Friday. My 2007 Panda 4x4 is making a strange whining noise. It's only there when I'm going 25-35mph and is most present when the car is cold. It is there in any gear within this speed range, and is also present when coasting at this speed in neutral. Any guesses what I'm looking for to replace here? Thank you very much!

 

[koalar]

I don't think it will be

But being a viscous coupling 4x4 it's best to check this first, driving with it lock stress the system

I will try and find a video, basically from cold lift a rear wheel and try and turn it, there should be some resistance but not locked solid

Hopefully it will be okay and we can move on

Here you go

 

[koalar]

Assuming the VC is okay

We will need to start to narrow it down

Check the tyre pressures

If you rev the engine is there any change, I guess not as it only happens between 35-50

When safe to do so you can move the steering wheel left and right to load up the wheel bearing differently, left to right side, if the noise alters it's almost certainly a wheel bearing

Does it sound front, back or centre

The microphone on the phone is pretty sensitive, you can record pointing back at a rear wheel then try the other and see if oneside sounds louder

 

[koalar]

At around the 4 second point the tone lowers,

What alters acceleration, deacceleration, a speed change