E46 Rumbling Noise

[FurtiveFreddy]

Thoughts please on what a low frequency rumbling noise could be from my 2001 E46 330i Touring.

It's there most of the time on all road surfaces but pitch of the sound doesn't increase with road speed.

It sounds like it's coming from the rear more than the front.

I've just jacked the car up on all 4 corners and all the wheels spin freely with no play and no unusual noises, so doesn't appear to be a wheel bearing unless it's only happening under load.

What else should I check?

[cuprabob]

It could be the tyres.

[duff]

I've had similar on a Z4 and Mini, in both cases it was the runflat tyres.

[crossy67]

The E91's are prone to noisy diffs, I can't see the E46's being much different. I had a customer ask me to change one as the noise was really bad, I went for a test drive but really couldn't hear what he was on about but then it wasn't my car and I wasn't used to it's normal noise.

I changed the diff and he was happy again for awhile, now he says he can hear the new diff making a rumbling.

[s m]

Obviously I've not heard the noise but there were a couple of TSBs from BMW on noise from the rear diff area.

Might get worth checking to see if you've had TSB330200 applied on yours. Can be more noticeable on a 330 Touring or Coupé.

My cousin had it on his 330

[iSore]

E46 diffs are nowhere near as bad as the small case E90 units. They eventually get whiny but never get to the Stuka dive bomber level the E90 (and 116i-120i-118d) can.

Rumbling can be a prop centre bearing or a wheel bearing. the latter is most likely.