Singing E53
 

Just developed a multi pitch high whine at 30 to 40 mph. 2001 220K. Is it just old age or am I getting transanoia? Any help would be appreciate.
Thanks
Mike

Ours has a whine from either a water pump bearing goibg out or the lash is wrong on the front diff. It sounds like we have a supercharger but it's been this way since we bought it and nobody has ever found the source.

Perhaps record it and see if we can help you after hearing it.

May be time to grease the front drive shaft splines at the transfer case. You can also change front diff fluid without too much effort.

Recording or guessing, your call.

Will it "sing" without a load (stopped in park) at various RPM or only under way at steady road speed/rpms?

Not affected or changed by road type (asphalt, cement, etc)?

Noise only when moving 30 to 40 mph

And the sound is regardless of being on the gas or coasting? If it's only when on the gas then points to driveline (tranny, t case, engine) if it's regardless could be a wheel bearing or another constant moving part. Does the sound change with brakes applied or when turning?

I was going to side with wheel bearing as well. Is it louder in cold temps while moving at that speed?

Just for clarification, no whine until 30-40 mph and then goes away or does it continue as you accelerate beyond 40?

Helpful diagnostic tests:

Have a passenger in the back seat move fully left to right to listen for relative loudness to attempt assessing left/right position. I use an iPhone app FFT to scan the sound signature.

Take a similar constant left vs constant right turn (or lane change) to help in left/right assessment. That test will almost always lock in if it's a bearing.

It's very possible that the tires have worn to a point where they are hitting a harmonic of suspension parts. Recording / FFT will help helpers help you.


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