importfanatic

What's good 'Driven? I have an 01 BMW 325i with an intermittent loud humming noise from the rear (primarily the passenger rear). The car just recently began to make the noise after I had a blow out on the passenger rear. I swapped my spare tire on (OE size) and the noise started shortly thereafter. After replacing both my rear tires, the noise is still there. It comes and goes and doesn't seem to be mph or rpm related, it's just seems to be at random. I've had the rear lower control arms replaced as well (bushings were bad), and obviously that didn't help either (didn't expect it to). The noise seems to be growing in intensity but I still can't pinpoint the issue. I figured if it was a wheel bearing/axle the noise would be consistent, maybe I'm wrong. I just need some input before this turns into a money pit...and nobody likes money pits. Lemme know whatcha got.

couped

recent alignment? sounds to me if you confirm not a bad wheel bearing its probably rear toe out cause chopped rear tires which will make that loud noise..
those beemers are famous for that..

importfanatic

Tires had no unusual wear before I aligned it. Just aligned it after I installed the lower control arms. The sound is intermittent, so I'm ruling out tires.

Fabrik8

Wheel bearings will often tend to be frequency and load dependent, so may not behave the same way all the time. Does it change when you go around corners?

If its a wheel bearing, it will start to make noise all the time as it gets increasingly worn.

importfanatic

I haven't heard the noise while cornering. Normally when the noise occurs it only lasts for about 3-5 seconds tops. I'm leaning more towards the wheel bearing over the axle. Moving back to VA at the beginning of the month, so I'm thinking about pulling the trigger on the hub assembly before taking the trip.

FLiPrayZin240sx

Did you check the rear shock tower? From what I've read, its pretty common on E46s.

importfanatic

No offense, but I've never heard of shocks/struts or the mounts vibrating a day in my life. Besides, shock/strut problems are RARELY intermittent.

Archer

it's hard to say without being able to hear it in person. did they check the condition of the trailing arms and bushings when they replaced the control arms? could be a wheel bearing, you can't necessarily hear them all the time when they're in the early stages of going bad.

snarf

diff mount bushing/guibo maybe?

Niburu

I'll second that, it sounds like the guibo to me