low resonant rumble

Hello
I just picked up a second hand Discovery 2 TDi (auto) today (72000 miles)and while driving it home noticed a speed dependent "rumble". It is a very deep sound a bit like big bass loudspeakers being over driven. The sound seems loudest at about 60mph, not as obvious at low speeds.
I don't think it has to do with the engine because if I put the auto gearbox into neutral at 60mph and coast, the noise is still there and does not change.
My guess is wheel bearings or tyres (supposedly just serviced and mot'd), would prop shaft cause it if not being actively powered by the engine?
Where do you suggest I start looking?
Thanks
Les

wheel bearing?
jack it up and look

Thanks Fanatic, quick response appreciated.
I have just got back from my local tyre dealer and had the two low tread Goodyears on the front replaced with General T2's, all four wheels balanced, and the two back wheels put on the front to swap things around a bit.
One wheel was out of balance and pressures were all over the place but the improvement was surprisingly slight and the vibration is still there.
At lowish (30mph) it seems ok but at 55-65mph there is that distinct deep vibration rather like running over rumble strips at lower speed.
Does this seem as though the next thing to look at is prop shafts?
Thanks again
les

Now running out of ideas.
Just got the car back from my local garage who tell me that the front prop shaft was replaced recently (found receipt dated August 2009) and seems to be ok.
They removed the rear prop shaft and I took it to be checked and it is ok, good bearings and all in balance.
New rubber doughnut thingy fitted on re-assembly as old one a bit soft.
All wheel bearings checked and found to be ok.
So all the easy bits seem to check out ok.
Next bit starts to get expensive (more expensive).
I have a gut feeling that the previous owner had the same vibration, couldn't fix it so traded the car in and got rid of it to the next mug... me.
A pity because apart from this vibration it is a good car.
Does anyone have any suggestions where to look next for the problem?
Les

What about the constant velocity joints

sierrafery said:

What about the constant velocity joints

Click to expand...

If you're on fullish lock and apply power do you get a rythmic knocking sound? That'd maybe indicate worn CVs.

How knobbly are you tyres & what pressures did they actually put in them for you?

I had the same problem - pretty much exactly..... and it was caused by the tyres. All 4 had to be replaced and all noise disappeared. A tyre specialist said is was quite common and that the noise came from the tyre walls as they flexed. I noticed it got a lot worse when I loaded a huge woodburning stove in the back... if you can load up yours and take it for a drive you may be able to identify the problem.

Anyway I ended up buying 4 new (decent quality) tyres and all was well.

John

Hi there,

Have been reading about the low resonance rumble on this thread and it makes you start to listen carefully to your car. But believe me I think you can listen too hard.

Was travelling back home from the supermarket today passing close by Sheffield United's graound when I heard a strange wop-wop noise when I pulled up at lights. Moved off and it went. Pulled up at the next set of lights and wop-wop-wop. Strange I thought,so pullled over just round the corner to see what it was. It wasn't till my wife got out of the car that she noticed the police helicopter a couple of hundred feet above us.

You can get too paranoid reading these threads I can tell you!

Regards