I'm having the same exact issue, main dealership technician told me this was normal for the W210 as they age and it'll stay like this for a long long time, nothing critical. But i'm not fully convinced, it sounds like it's tied to wheel revolution making a "wooooow wooooow wooooow" sound in that same exact speed range and it started doing it right after I replaced both flex discs replaced.

I'm not sure if I want to go in and replace the central bearing boot, bearing and rubber support but I suspect this might be it, technician told me if it were the bearing or the boot the sound would be much more pronounced.

That's just my 2 cents on the matter, same boat as you are in My 97 E200 has 240K Km and never had major suspension work done.

 

Yeah that sounds like exactly like the same sound i'm experiencing. I'm guessing you don't have trans/shift issues? I replaced both flex disks and the central bearing a while back didn't have any sounds since last summer. I think if you're going to go through all of the flex disks and central joint it's also worth it to start looking into changing the u-joint as well, that is the only thing I haven't replaced on the car and I hear they generally go back above 250k

 

Here is are 2 videos of the sound. I tried to get the phone as close to the shifter as possible, you can hear the groaning in the background.

Car is somewhat warm -

Car is cold -

 

Jeremy,

Yes, it is possible it is the propeller shaft center bearing. Check for loose bearing, but the reality is it can be the bearing, yet sadly you have to get it out to inspect it.

Springs....Valve springs-well I would change this guy:

https://www.sonnax.com/parts/2313-regulating-pressure-control-valve-spring

Your transmission being a 99, may have an updated valvebody, so it may not have the regulation spring above, but it may have have this one:

https://www.sonnax.com/parts/2325-tcc-damper-valve-kit



Oh yea a conductor plate can be at fault too, so check the speed sensors for hairline cracks with a magnifier...

It can be a black regulation solenoid(s) too, but my suspicion would indicate the problem would be when the transmission is hot, yet not cold...

I'd even inspect the transmission filter for it falling on the pan, or the element getting restricted....

I'd would not rule out a very rare possibility of cooler failure.

Orrrr.... no flow of the transmission pump, and for this you can disconnect the drivers exit cooler line going to a the radiator, and the flow should be like 15 to 20 seconds per quart while the engine is running in park.

This what comes to my mind, so I hope it helps..

Martin

 

Jeremy,

Your transmission being a 99, may have an updated valvebody, so it may not have the regulation spring above, but it may have have this one:

https://www.sonnax.com/parts/2325-tcc-damper-valve-kit

Checked the old photos I had. Does not have a damper spring.

 

If the diff is a possibility, i'd certainly check that out first. You say the noise is present in neutral so, could be a possibility. Have you done a diff fluid swap, or opened up the cover previously?

Not* present in Neutral. The fluid was changed probably 2 years ago. Cover was never opened.