Bearing Noise (road speed related)

[Robho]

I have a 2006 1.6HDi. 

An unwelcome recent addition is a 'thrumming' bearing noise which starts around 40mph and gets more noticeable at 50mph and above. 

The osf wheel bearing seemed a bit noisy when tested stationary, so just replaced it today...unfortunately no real difference. 

Having driven the car afterwards, my local independent garage thinks it is likely the diff bearings.

Any way to test this? 

And what is involved (and the options, if any) for resolution would be greatly appreciated pls. 

It doesn't cover a large mileage - my wife uses it for local markets, but we do need it to be reliable. Any views on longevity (noise started less than 1k miles ago) if we can tolerate the noise?

Cheers.

[SinsBird]

Check the gearbox oil level first. It might last a reasonable amount of time without repairing it but there would be less parts to replace if done soon.

[Robho]

Check the gearbox oil level first. It might last a reasonable amount of time without repairing it but there would be less parts to replace if done soon.

Thanks.. Its a manual gearbox, is it a case of removing the filler plug to check the level (and where is it if so)?

[Robho]

Found this Youtube, showing fill/drain plugs

https://www.youtube.com/watch?v=95QarTgx4mI

[cancunia]

Check the gearbox oil level first. It might last a reasonable amount of time without repairing it but there would be less parts to replace if done soon.

Thanks.. Its a manual gearbox, is it a case of removing the filler plug to check the level (and where is it if so)?

I'd double check your gearbox looks like the attached but from memory it looks correct. You can refill the correct amount via the breather at the top or via the level plug. Have a search around on here for the correct oil type.

[Robho]

That's an excellent and very clear document - thanks.

Must admit, I'm kicking myself for not thinking of the gear oil myself. There's no sign of any loss, so hopefully, the level will be OK.

Would you expect a change of gear oil would make a significant difference? I.e. should I get the oil and just do it anyway?

and any comments on what is involved if the problem is due to the diff bearings would be great.

thanks again

[cancunia]

You should find that the gear change is a lot easier.

I'm no expert when it comes to diff bearings, so will leave that to others.

[SinsBird]

Lower viscosity = less force required for gear to engage, higher = more.

[Robho]

OK, tried changing the gear oil, not really made any difference to the noise (as you'd expect really)..so it looks like a gearbox job...I'll start a new thread.

[brodfather11]

Is there an intermediate bearing on the offside drive shaft on yours.? They can sometimes run rough.