I have a 1985 240dl that for the past couple of years has developed a whistling noise that sounds like metal on metal. At first it was intermittent and seemed to do it mostly when it was colder out. I was more concerned about brake block leakage, and transmission oil leak that has kept myself busy the past 8 months. Now that I have fixed the fore mentioned issues the whistling noise now has 2 tones whistling is more consistent and does not depend on the temperature outside. Hard to tell where the sound is coming from. First thought was on the passenger side, the whistling subsides when I take my foot off the gas a decelerate. Any ideas would be appreciated, I have been scouring the internet and coming up empty.

 

Does the whine change pitch with speed or with engine RPMs? If it changes with speed then I would suspect the center carrier bearing on the driveshaft.

 

does it only make noise when the car is moving?

 

Thank you for the quick reply. Yes, it only makes the sound while moving. Higher pitch when accelerating and lower as I decelerate. I recently had fixed a transmission leak from the tail shaft replacing the bushing/seal. It does make sense that it would be the center carrier bearing.

 

Also, check for any play or unusual movement when the drivetrain is on. If something feels loose or moves oddly, it could confirm that the bearing is indeed causing the problem.

 

Thank you for the suggestion. I moved it in the garage last night to put it up on stands. I will get a chance tomorrow to put her up and check the bearing.