2006 CDI car vibration or resonance?
 

Need some ideas as to what may be the problem. The car resonates or vibrates at stop when in drive. If I put the tranny into N then the resonance or vibrations goes away. It normally happens when the car is cold. When the car is warm then it happens sometimes. Engine mount changed 20k ago. I thought it may be the tranny mount and it was changed but didn't fix it. I haven't checked the flex disk yet. Any suggestions?

Engine mounts?

Check the alternator freewheel pulley and see if it is starting to seize up.
If is is going bad it will behave the same as a solid pulley and give vibration.
https://youtu.be/4EXYP1CmL9Q

I will take a look. But it doesn't explain the vibration or resonance goes away if I put tranny in neutral or frequency is much less after car warms up.

Motor mounts for sure. Putting the transmission in neutral removes almost all the torque from the engine against the body.

When the car warms up, the rubber softens in the mounts and makes them more absorbent.

Did you get a genuine trans mount or aftermarket?

Exact same issue has started in my W211 OM642 this winter. I am curious if you find the cause but also suspect motor mounts. It is not my top priority because it only happens when cold outside and it still feels like fall here in TX!

Engine mounts are one of those things... you’re not sure how bad off it was until you go ahead and get new ones. Then you’re like... WoW, I should have done this sooner.

Absolutely! Just had the mounts redone on my 2013 E350 (Still under CPO warranty, FTW!)

It was starting to sound and idle like a Massey Ferguson tractor.

I could tell the difference even before I got in it when they pulled it up into the service area for me to take home.

It’s almost silent at idle now. I keep looking at the tach to make sure it hasn’t died…

I second looking more closely at the mounts.

Check the mount height from the crossmember. I did a couple of cars this year where the mounts looked fine but a side by side comparo with new mounts showed how worn they were. Big diff too after they were changed out

Is the motor mount identical on left and right? I plan on changing them. One has a heat shield but apart from that are they the same?

The problem was the mount. They were changed out in Dec, 19. I looked at the old and new and found I was conned by the eBay vender. I buy Mercedes original this time and the mounts have different part number, left and right. The old one I bought was marked 202 240 49 17, same # for both left and right. The 202 and 211 mount looks identical but the 202 is a bit shorter so I didn't notice. Basically I overlooked it, my fault.