e38 740il whining issue (with video)

[Jormotors]

Hello, i recently purchased a 1997 e38 740il. Car runs and drives great but makes a loud whining noise in correlation with RPM's. When i first heard it it reminded me of how a transmission whine sounded on my e32 740i but if I rev the car in neutral or park it makes the same noise and the transmission always shifts smooth and easy. I'm thinking it could be a pulley, or alternator pulley, or something similar but don't know. I read the service engine light and it came back as torque converter solenoid, but don't know that is relevant to this issue. Here's a Quick video of the noise. Any help would be appreciated.
https://youtu.be/17MSGIoMp30

[psjr]

It does sound more like transmission than anything else, but you can always take off the belt to check if it's a pulley.

[cazal740i]

PULLEY!!....Pull the belt off like PSjr said and spin each pulley 1 by 1 . They should all be smooth and free spinning.

[Jormotors]

Thanks! will do.

[Al750i]

I had a similar sound before on mine last year...as the RPM, the same sound could be heard. Like you, the Transmission shifted pretty smoothly. In the end, I decided to get a genuine kit from BMW for the transmission service and did an oil change for the Transmission with a new filter and gasket. The sound never returned again.

If your car hasn't had a transmission fluid change, maybe you may look into doing that also.