Rumble noise from the engine at certain speed

Hello, boys.

I have a little question for experienced screwdrivers: I drive an S6 with AEC engine and have
This is the case for a long period of time. Vibration noise in the interior between 1200
and 1400min-1. This noise is noticeable when the engine is turned off and driving at a slower speed
because the idle is slightly increased there in this speed region. Of course, you can provoke the sound,
In this case, the idle speed as stated approx. between 1200 C.E. 1400min-1 stops. Notice
would be that the noise only occurs with the warmed-up engine.

Now I've gone after it, removed the engine bearing bridge at the front right, and found that
the noise is transferred into the interior, disappearingly less (kaum mehr audible). I'm sorry.
have shaken the engine vigorously, and finally re-installed the storage because I externally
no defect could be detected. But this action should not solve my problem, the noise
was to be heard in previous intensity.

Now I've grabbed the stetoscope to listen to the engine and its aggregates. The first time I am
I got stuck with the oil cooler, the sound of resonance was loud, it had to somehow
come from the oil pressure system. I tracked the oil connections and landed at the oil pan. When I did this,
==References====External links== In the middle of it almost burst my eardrum when the sound came.
I now had to find that the oil tub floor oscillates of certainly several
Tenth of a millimetre, you could feel it with your hand.

Now my question is: Has any of you ever had anything like this before? I don't feel like it now.
Needless to say, unscrew the oil pan, new seal, oil etc. buy, look in and then
nothing to see, to rebuild everything and to continue with the sound :-)

I would be very happy about relevant tips, experiences or tips!