Quote:
Originally Posted by Brian Carlton
The determination of "differential" or "wheel bearing" can be assisted if the following question can be answered:

Does the noise almost go away entirely when the drive shaft is unloaded?

The drive shaft is unloaded when you are cruising along at a steady speed and you lift your right foot ever so slightly so that the vehicle just begins to slow down. If you lift too far, the shaft will load up in the opposite direction and the noise may return.

Please attempt to reduce or eliminate the noise via your right foot, in the manner described, and report back."

I saw this post in the diesel forum and I think it might pertain to my car. I have an 1982 380SL with an honest 52k miles on it. It makes a whirring or whining noise that starts around 60-65 mph a gets a bit louder as the speed increases. If I lift on the gas pedal the noise will go away until the car slows down and it comes back when I think the drive shaft is loaded again. I have checked the wheel bearings and the diff level is correct. Any Ideas?

Thanks Steve Dabney

Check the diff oil level and change it, if it looks as though it hasn't been changed for a while. . It's not unusual for the W126 to have whining diff at one speed level . Normally around the speed you mention

The level is correct but I think I'll drain the Lucas synthetic and replace it with Swepco which is what I run In my 911 race car.

Thanks MM

I recall having a similar noise on my '72 SL, but darned if I can remember what it was. I have never had any work done on the drive components, so not that. Might have been tires or maybe something to do with a stuck rear caliper.

On my 300D, I have had similar situation twice. Once it was the drive shaft support bearing. It would develop a harmonic at some point and really roar! Other time it was the driveshaft flex disk after engine had been out.

It might also just be something loose underneath, like an exhaust hanger or heat shield vibrating. If you take mercmad's advice and get the diff oil changed, it may be a good time to inspect the underside for loose items as well as have a look at the u-joints, flex disk and the mid-shaft bearing. This link has a picture of your driveshaft:

http://www.driveshafts.com/pages/mercedes_pictures.html

__________________
Graham
85 300D,72 350SL, 98 E320, Outback 2.5

each time an engine has been out,get the car sitting on it's wheels before tightening the center bearing housing and slip joint. This preloads the bearing correctly. It's even more important to do this on W111,108's etc where the cross member is designed to float. Center bearings can be bought cheap any where and the rubber center support needs changing every 10 years. Although i have 2 finny's in at the moment which still have good support rubbers after 40 years.

I think the W107 diffs of the 70's era had the whine and was determined that it was design, I actually have a newer ( kinda) diff on mine and the whine is gone

__________________
Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace