Wierd low frequency drone making me deaf in one ear!

[MPETT]

I bought myself an e36 328i last weekend and it drives sweet (Mreg 71k). However I noticed that when pulling off first thing in the morning there was a grinding noise that went away after 10 secs. I suspected the slightly corroded discs, but after a 400 mile journey my left ear felt like it had been at a rock concert. (dull drone). I thought it was my cold again, but after work I turned off the radio and there was a low rumbling noise. I tried the following actions to stop the noise:
- brakes on and off, varying pressure
- put auto in neutral
- varied engine speed (not obvious at low speed, but always present over 15mph)
- tried swerving to make noise louder/stop

None of these made any difference.

My thoughts are that it could be the prop bearing, the diff or the wheel bearings. Does anyone have an oppinion?

Cheers,
Martin

[< FORZA WEST]

Sounds like a differential problem,but before you go down that route what sort of tyre have you got (avons,kleber) are they directional.Also check the wear pattern,has it stepped on the inner edges.

[derin100]

I'd jack the car up and check the wheel-bearings first...that noise can become unbelievably loud and droning in my experience.

[Talkwrench]

I'd go with wheel bearings as the most likely bet.... and I'd suggest near side rear. Front usually exhibit the better/worse pattern as you change direction but rears are not so prone to exhibiting this tendency. Jack each wheel up and see if there is any play present. This would be a giveaway as there should be no play whatsoever (the bearings are not adjustable).
Unlikely to be the diff at this mileage and propshaft noise tends to reverberate through the car. You'd be deaf in both ears!
Tyres are certainly a possibility. I has a pair of dreadful Avon ZZ3's on an 850 for a while and was convinced I had worn rear wheelbearings. All noise disappeared when I threw them away. (Never buy any. Theyre dangerous!)

[MPETT]

I've had it up on a lift and the mechanic checked all the bearings. There was a ticking noise coming from the diff. Has anyone else heard this noise in their diff? Sounded more like the pinion rather than bearings. The mechanic advised me to try some friction modifier from Jeep to see if that would smooth things out. I'll need to do 200miles before I know if it sorts it. Whilst I has there however, I noticed the rear tyres are budget. I don't een recognise the brand! Has anyone experienced noise related problems from cheap tyres??

Cheers,
Martin

[RS4john]

derin100 said:

I'd jack the car up and check the wheel-bearings first...that noise can become unbelievably loud and droning in my experience.

Yep seconded. Lightly use the hand break whilst driving and see if it damps it out, if so it's w/bearing.

[< FORZA WEST]

MPETT said:

I've had it up on a lift and the mechanic checked all the bearings. There was a ticking noise coming from the diff. Has anyone else heard this noise in their diff? Sounded more like the pinion rather than bearings. The mechanic advised me to try some friction modifier from Jeep to see if that would smooth things out. I'll need to do 200miles before I know if it sorts it. Whilst I has there however, I noticed the rear tyres are budget. I don't een recognise the brand! Has anyone experienced noise related problems from cheap tyres??

Cheers,
Martin

Yes (as above)we get an awful lot of issues with tyre noise which gives off a noise very much the same if not louder.Avons,Kleber and so on are some of the worst.As are runflats on the latest models.
Aftr a thoughrough check over,I would then be tempted to swap the rears to the fronts to see if the noise changes pitch and postion.