70-80 mph on leaving the throttle I hear a very faint but definitely present whining sound coming roughly from the front passenger side. Goes away on acceleration comes when I leave the throttle. Does not seem to come from engine as I have put in park and revved up to no ugly sounds from engine. It is an AWD car and recently got the tires rotated when I began to notice this. Since then I have checked the tire pressures, changed brake rotors and pads (they were due) and no change at all. I haven't changed the oil in the tranny yet and was thinking of getting it done aroung 60-65K miles. All shifting is smooth still and never had any issues. No other symptoms or problems.

Should I be investigating the tranny, front differential/transfer case or rear differential etc??
Any clue or guidance??

I did search and did not find anything similar to what I am hearing .. etc.

TIA

 

I detect the same whine under similar conditions on my 2006 530XI Touring. I replaced all drive-line fluids at 98k miles. Then again at 135k I changed the Transmission fluid, both differentials, transfer case, and the CHF 11S power steering fluid. The whine is very faint and I do not always notice it. My car now has 152,000 miles and is going strong.


FYI, the changed fluids were dark but had no debris or grit. The fluids were slippery and fulfilling the duties of the Tribology specifications set forth by BMW.


tri·bol·o·gy
trīˈbäləjē/
noun
noun: tribology

1. the study of friction, wear, lubrication, and the design of bearings; the science of interacting surfaces in relative motion.

Anyhow, I believe the whine in my car emanates from the Transfer Case. Since the transfer case is relatively inexpensive compared to the price of a new 530XI, I am not too worried.


My advice is keep the fluids clean.

 

When you change the transfer case fluid, you need to have something in the transfer case recalibrated.

 

No calibration needed. I have changed the fluid twice and never experienced a single error code. No "DSC 4X4 Failure" ever and I drive 400 to 800 miles every week. Bentleys does not mention a calibration on the transfer case, however, the automatic transmission is an intelligent system and adapts to my driving style. The transmission can be reset via the accelerator and key in position two type procedure.


The Bentleys manual does state that after the Transfer case fluid fill the car should be driven 100 to 200 feet then topped off with fluid again. This allows for the fluid to be sucked up into the clutch discs. I do not perform the refill procedure because on the 530XI Touring (Wagon) requires the exhaust to be dropped to access the fill/drain ports. First fluid change was at 98,000, and the second was at 135,000. Current mileage is 152,000.


Note: You must use the BMW transfer case fluid for $55 per quart. No Substitutes.

 

Regarding the whine on my car; there is a chance that the whine could be the bearing the supports the drive shaft. I do not think it is likely the "driveshaft center bearing assembly" because there is no vibration detected. If that bearing was whining I think the noise would continue to get louder and there would be a detectable vibration.

 

I don't exactly remember all the details, but I found this online after a couple minutes:

"Transfer Case Oil and Monitoring:
Oil Monitoring is performed by the VTG control module to determine when a service (change) is due. The VTG calculates transfer case and clutch wear based on the amount of slip, engagement pressure (torque), speed and mileage. This calculation accounts for normal "dry" road driving, "adverse" road driving and "other" road extreme driving. Depending on individual vehicle use - driving styles and driving conditions, the transfer case oil service interval will vary. When a service is due, this will be indicated by a Fault Code and additional details are available using the DISplus/ GT1. Service functions provide directions on changing the transfer case oil and updating the VTG control module with the necessary reset and adaption procedure. This is extremely important for CBS."

I don't know if that means that you need to "reset" after any oil change or just after the CBS says to change the oil.

 

That is a good point. The independent shop did not indicate there was any concern regarding the VTG or CBS. Below is what the Bentleys manual states. I hope this is the answer and that there is not a reset required.


" Because of mechanical tolerances in production, the characteristic curve of the multi-disc clutch locking torque varies slightly. At the factory, once the actual locking torque is measured on the clutch test bench, a resistor is attached to the clutch actuator. The resistor value (classification) determines clutch locking torque characteristics.
Each time the engine is started, the transfer case control module measures the resistor value once and selects the optimum program map for transfer case engagement."


Since the test bench measurement was taken with clear pristine fluid, I would assume the torque characteristics are closer to the factory settings than when it tests itself with worn out black fluid.


By the way the fluid was as black as tar the first time I changed it at 98,000 miles.