BMW Repair Questions? Ask a Mechanic for Answers ASAP
This could be a few things but the most likely cause is a bad wheel bearing. The symptoms of a wheel bearing can vary to noise at certain speeds to noise when turning. The first thing I would recommend would be to swap your rear tires to the front to see if the noise moves. This will help rule out that this is not a tire noise issue from irregular wear on the tires or a bad belt inside the tire. If it does move to the front then the tires are the main issue.
You can try to turn tight circles and see if the noise occurs while turning in a circle. This helps to load each side and can help localize which side the wheel bearing may be bad but I have seen both go at the same time. If the noise persists then the next step will be to have it checked on a lift and using a stethoscope the wheel bearings can be checked for noise to localize if it needs one or both wheel bearings.
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Thank you for the replay back.
It is not overly common but I have seen a few drive shafts cause some noise. This occurs in two ways that I have seen. There is an inner sleeve inside the drive shaft that can detach and make a noise under load but this often sounds metallic.
The other item is the center bearing on the drive shaft. I have seen this make noise under load. This center bearing can be replaced separate than an entire drive shaft which is good. The difficulty with a problem like this is that noises in the drive train telescope in the entire system. So what often sounds like a bad differential for example is really a bad wheel bearing or drive shaft. Since the wheel bearings where replaced and replacing the center bearing may be the best step.
I have seen bad wheel bearings out of the box so keep this in the back of your head in case the noise is still present. If you raise the rear axle and drive it with it in the air you can use a long screw driver like a listening device with your ear on the handle to see if the noise is from a wheel bearing or hold the spring and feel for the vibration in the spring which is another good test. If the bearings check out good then the drive shaft would be my next step as well.
I hope this helps.
The noise often can travel (telescope) through the drive train. This is very common and makes noise locating difficult when looking into a noise like this. It would travel down the driveshaft and possibly even into the rear differential. The same is for bad wheel bearings.
To check this in the air, press and hold the DSC button in the vehicle while the car is running. This will disable DSC and allow it to be checked while lifted. This may set wheel speed sensor faults that will need to be then cleared out of the DSC/ABS unit with a scan tool.
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I hope you have been well :)
Do you have any check engine light on or any warning lights coming on? Do you hear any noises during acceleration? Can you explain the first time you noticed this and any other symptoms you have?
Thank for the information. This may be an unmetered air leak, a problem with the DISA flap or clogged air filter to name a few items.
The first thing to check is the throttle boot near the elbow that goes to the idle air control valve. The throttle boot can crack from age and cause a noise and loss of power. The best way to find an unmetered air leak is to have a smoke test performed. This costs about 1 hour diagnosis. Or take a good look at the throttle boot for any signs of cracking. Especially in the folds of the throttle boot.
Here is a DIY for checking the throttle boot that I like:
Also you can check the DISA flap. I have a video of a failed DISA flap I made that can cause problems.
If all this checks out then take a look at the engine air filter and replace if it looks dirty.
If nothing can be found then this may be a bad mass air flow sensor. The best thing to do would be to have the dealer test fit one for you so that you do not have to pay for the part unless you know it fixes the problem.
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Thank you. :)
This is a common failure on the E46. The transmission would often not last past 100k and a replacement is needed. Since you have already checked the fluid level and attempted a repair the next step unfortunately is a replacement transmission or having it rebuilt at a transmission shop.
The internal clutches slip which causes the high rev. I am sorry to hear you have had this failure. I wish you the best with your repair.