Whine - goes away when car warms up

[JLF]

Hey folks,

I own a 89 325is. The car had a transmission leak. A private party inspection cited "Rear transmission seals and detent cover." I had this work done at an independent shop. And as a preventive step, i had them install a driveshaft bearing replacement kit and flex disc/gubio replacement kit. Since the work was finished, I have notice a whine that does not go away when engaging the clutch. The whine does go away after driving for 15 mins or so, but returns upon a cold start. Any thoughts? transmission bearing? coupling between drive shaft and transmission? spline nut on the driveshaft? I appreciate your input!

[JLF]

probably does not belong in this forum. Sorry

[AndrewBird]

Maybe the shop didn't top the transmission off with fluid? Might try replacing it with Redline MTL. It will smooth things out and quiet it down.

Could also be a worn diff. Can you pinpoint where the whine comes from? I'm assuming it only makes noise while the car is rolling?

[JLF]

Thanks for your comments, AndrewBird. Checked the diff fluid. No problems there, and you are correct, car only makes noise when rolling. Almost sounds like a whistle. Hear it the most at 20 mph and 50 mph. Seems to go away after driving about 5 to 10 miles. If i let the car sit for a couple of days, it comes back louder. Taking it back to the shop this week, just not sure how knowledgable they are.

[pandaboo911]

Get the car on a lift and put it in gear to pinpoint the whine before you have a shop replace random shit trying to find it

[Kershaw]

turn the radio off, does it go away then?

[JLF]

Hi Kershaw. Thanks for your input. Unfortunately, I have not had the radio on when the car has whined/whistled, so I do not think this is the problem.

[Nesset]

I would check EVERYTHING that the shop replaced. Also, check out those trans' mounts. I know on 2002's they go bad and cause vibrations and noises that people can't seem to explain. Guibo is a good place to look as well. Maybe the seal was installed improperly? Anything is a possibility. Good luck.

-N

[JLF]

Thanks for the help, everyone. The shop diagnosed the sound as the rear transmission bearing. I had read in Bentley that it is very important to tighten the rear transmission bearing nut to specs, and the shop claims that they did. Couple questions: the bearing was not replaced. can tightening to spec harm an old bearing? Also, shop recommends adding a Lucas transmission treatment to try and coat the bearing. Any issues there? Shop said most of my transmission leak is coming from shift rod. Does this sound right? And might the lucas treatment help with this issue. Thanks!!