I have a 2001 325Xi with about 59K on it. The rear end hums above 50 mph and only gets worse above that. It seems to be coming form the center of the car. The rear wheels are new and the tires are new. The brakes were changed and did not change anything. It is not a tire balance issue, I have had them checked and rotated. It seems to be a bearing noise, and does not change even when cornering. Anyone have any experience with this sort of issue?
Mine has had a hum ( '01 325i Steptronic) from the diff since I took delivery off the truck. Back in the day when it was months old, a tech rode out with me, and kept saying it was the tires. The car now has 65K miles, and the noise has not changed, even though I have different tires on the car now.
Diff noise Just a thought, but have you had the differential/transfer case serviced recently? If so, perhaps the incorrect fluid was used. I see the Xi portion and guess that it is all wheel-drive?
Hello, I have 2001 330Xi with 141000 miles and I had the same problem, I change the transfer case fluid, and help a lot, you have to use MTF- LT-2 from BMW or Red Line MTL, the problem is that only takes .2 of a qt. I will change too the front and rear diff fluid too, that one takes Red Line 75w-90 sintetic. Good luck
My 2003 325xi has the same type of noise. It hasn't changed since I bought the car at 39000 miles, and now it has 57000. I actually checked the musical pitch of the noise and related it to the frequency that the driveshaft turns, so I've been guessing out-of-balance driveshaft -- but that's just a guess, and I haven't done anything about it, since it isn't changing. I'll try the fluid change for the transfer case when I take it in for the "big" maintenance in a couple of thousand more miles!
