What is the whining noise coming from the rear end of the car?

CHRISTOPHER SA

MEMBER
1993 BMW 320I
2.0L
6 CYL
2WD
MANUAL
117,066 MILES

I am not sure when the whining or droning noise started but it has become very noticeable recently. It is coming from the rear end of my car and gets to be noticeable above 25-30 miles an hour. I have uploaded two audios that I took with my iPad4 while it was resting on the armrest between the front seats with the microphone pointing towards the back of the car.

You can hear the noise as a constant moaning/droning/whining that goes up in pitch when going faster and lower in pitch when going slower. I have made two short audios of about 2.5 minutes each.

Is it the wheel bearings or the differential? Or something else?

Note: Please allow mp3 files to be uploaded as otherwise I have to convert mp3 files to the mp4 format with an image, which is a real pain to do. You do not allow mp3 files to be uploaded at the moment.

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3 Replies

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Hi,

I do hear it. It is more noticeable in the second video. The sound can be an axle bearing, a carrier bearing in the differential or even the result of tire wear.

First, check the tires for cupping or feathering.

Take a look through this link to check tires:

https://www.2carpros.com/articles/how-car-tires-work

Also, I attached two pics from the link below that are specific to what can cause this type of noise.

If the tires are smooth, evenly worn, and have no high/low spots, then I need you to pay attention to see if the sound changes when making turns.

Also, check where the driveshaft attaches to the front yoke on the rear differential for evidence of an oil leak.

Let me know what you find. Also, the 320 isn't offered in the US. But I will try my best to help.

Take care,

Joe

See pics below.

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Thursday, October 27th, 2022 AT 8:37 PM

CHRISTOPHER SA

MEMBER
206 POSTS

Hi again!

The tires are very new and have only about 1,800-2,000 miles on them, if that. I have checked the tire tread within the last few days and no unusual wear pattern is evident. I have not noticed any change in the sound when going around corners.

Yes, I thought of the yoke too but forgot to mention it. I will see if I can find out if there are any oil leaks in this area (I say it this way because my car jack has broken so I will have to get another one or come up with another way of looking under the car in this area).

One of the projects I had on the to-do list was the rear axles and bearings. If it's the carrier bearing in the differential or the differential itself, how will I know for sure without taking it apart? By eliminating the other potential causes?

The 323 is basically the same car but with a bigger engine.

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Thursday, October 27th, 2022 AT 9:08 PM

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Hi,

Sounds like a plan. As far as locating a bearing issue, if you have a bad one, usually you will see a leak at one of the seals.

Other than that, a tool designed to let you hear each wheel area, one at a time, is made. You can block one side at a time to only hear a specific area. However, most people don't own one.

Let me know if you notice any leaks at the differential. Also, if you haven't already, make sure it is full of gear lube.

Take care,

Joe

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Friday, October 28th, 2022 AT 9:28 PM