(1.9 JTDm - 6 manuel gears - 70.000 miles)
I'm desperately trying to find the source to a low-frequency rolling noise
- It is heard most clearly between 30 mph and 60 mph, not loud but always there when rolling.
- Noise is very homogeneous, sounds like "wuuuhhhhhhh" ... can't record it - difficult to describe
- It is heard from the engine compartment - think it is something related to transmission line
- The frequency changes as a function of the speed of the car
- The sound does not change regardless of which gear it's run in.
- It does not matter if the clutch is activated or not
I have checked wheel bearings but can not provoke changes in volume/noise by turning the wheels - eg. at roundabouts.
I have changed gear oil without it has changed the noise
The gearbox seems healthy.
The gear selector does not vibrate when driving.
No 5. or 6.gear spec. noise
Power steering was previously changed (oil reservoir and fluid)
Brake discs are brand new so the noise does not come from a hanging brake.
New tires, same noise as the old ones
I wonder if theres one or more bearings on drive shafts that might fail?
Any good ideas where or what to look at?