Technical Pulsating humming/buzzing noise when going 110-130 km/t (dissappears when clutch is depressed)

[panda81]

Dear forum members.

Recently I noticed this annoying issue with my wife's Fiat Panda (1.2L, manual, year 2008, 280kkm).

The other day I was driving on the highway and noticed that at approx 110 kmh there is a noticable deep sounding humming noise and it is not constant but more like pulsating:

BZZZZZ----BZZZZZ-----BZZZZZ----BZZZZZ

it gets quite loud at 120-130 kmh. I dont think the pitch changes, but I am not totally sure.

When I depress the clutch the noise immiediately disappears.


Driving under 100 kmh there are no sounds or anything - the car drives perfectly.

I dont feel any balancing issues or pulsation in the steering wheel.


I changed front wheel bearings recently as they were bad, steering was aligned afterwards. So bearings should be ruled out. I also changed the outer joint on the driveshaft some years ago.

Any suggestions as to what is causing this issue. Could it be bad clutch or release bearing (the car is still on the original).

Please any advice would be appreciated. thanks.

 

[koalar]

Sounds like the release bearing or input bearing

If you leave in 3 gear does the sound start to happen at a lower speed

Is there any oil in the gearbox

While it's making the noise shift to neutral and release the clutch does it still make the noise in neutral