Hi all,

This is a follow-up of my previous post wherein I detailed some whistling noises while driving (see https://www.youtube.com/watch?v=9Q7npcWBJCs )

After a lot of confusion and a lot of research, I'm beginning to think that the same issue may be causing several symptoms that I'd previously thought to be unrelated, namely:

• The car makes a rhythmic rubbing noise when starting at very cold temperatures (we're talking below 35F or so). This worsens as ambient temperature decreases but inevitably subsides as the car warms up. On warmer days (40F+) this doesn't appear at all.
• There's a slight throbbing vibration when driving right around 60-65 mph on the highway. It isn't particularly violent or loud, but it is consistent , low, and noticeable.
• The very intermittent whistling/whining (whatever you want to call it) that's shown in the YouTube video linked above. Mannys9130 suggested that it could be a worn differential, but everything I've read/watched about differential whine suggests that the noise would typically subside when coasting and return under throttle (this isn't the case here BUT also feel free to correct me if I'm wrong). The sound also doesn't seem to explicitly come from the rear, though it's been very difficult to pinpoint. This seems to occur completely at random, independently of ambient temperature, whether the car is "cold" or "warm", payload, etc.
• Occasional clunking when the car downshifts.

Visual inspection of the flex discs yielded no red flags (no cracks--they look pretty new actually), but I'm beginning to suspect that the center driveshaft bearing/support may also be a (the?) contributing factor along with the diff. Knowing my luck, both will need to be replaced.


The next step will be to send the car to the indie to try and pinpoint the exact cause of the issue(s), as this is a lot to address without having the ability to safely lift the car and inspect (all I have is ramps).



I'm interested in hearing if anyone here has had a similar collection of symptoms and if so, what component(s) ended up being to blame. Can a failing center driveshaft bearing produce a loud whining noise as well as some or all of the symptoms described above?



I'm also considering sidelining the car (was originally planning on driving to Boston this weekend) until all of this has been addressed. On the other hand, it's covered several thousand highway miles whilst intermittently exhibiting these symptoms without any of them growing worse, but the gripping fear of catastrophic driveline failure is making me reconsider this. Having the center bearing support let go at speed seems like it could really ruin my day.



All input appreciated.

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1) Rubbing noise in cold - could be uneven brake pad wear/warped rotor, out of round or blemished tire(s)?

2) Noise at 60-65 mph - probably unbalanced or out of round tire(s)?

3) Whistling/whine noise - dried or malpositioned seals in U-tube (connecting air clearer to turbo inlet)? Bad weatherstripping

Those are the most likely suspects.

For 1) and 2) try rotating the tires and see if the symptoms change, also check if there is evidence of any wheel weights recently gone missing.

The exact cause of errant noises is sometimes very difficult to pinpoint.

Hope it is something simple.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Flex discs?

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UK spec Mercedes W210 E300 Turbodiesel wagon - OM606.962 with 722.6 transmission - rust free!

I chased a similar sound, rarely drive the car in the winter but it always makes a rhythmic dragging/whoosh-whoosh type of sound when I first start out on a very cold day. A couple of miles and it clears up. It also gets quiet when I lift the throttle, comes back with light throttle.

The driveshaft center bearing is the only thing that hasn't been done in that car, and I am reasonably certain that it is coming from the tunnel area between the front seats, not from the rear (which in a wagon, is fairly easy to tell with a passenger behind you listening for you).

I have the bearing, it's on the list when time allows, but as I don't drive it much in the winter it has gotten low priority. The car has been driven ~30k miles since I first heard it without any change, ... still only when it is very cold.

Ironically the SD (which I DO drive in the winter) also has a much more evident sound, coming from the center of the car / tunnel area, more of a whirring sound that occurs when it is below ~25F. Louder and easier to place, must be in worse shape, an $8 bearing IIRC, will order and replace this week. In the case of the SD ('93), it is so much easier to place the noise in type and location, partially due to the massive sound-deadening on this car / quiet cabin, and partially due to the more obvious bearing sound.

The frequency of the sound will tell you if it is wheel-end or trans-driveshaft-diff as the wheels turn more slowly, the driveshaft turns 2.65x for each wheel rotation.

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Gone to the dark side

- Jeff

If you are handy with a soldering iron, get one of these FM Audio Surveillance Wireless Microphone FM Transmitter Frequency 85 115MHz G | eBay , add a small 3 V Lithium button battery, set it up as a contact mic with a strong magnet. This thing is small and light enough to put anywhere under the car so you can move it around and localize the source of the noise. Light enough to put on the drive shaft temporarily (add a counterweight if you are concerned about balance). I would not rely on the magnet alone if it is spinning and add tape to further secure.

It looks so useful I just bought one.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked