I believe I see item 68, which is a right-angular bracket the supports the
front of the oil pan.  There appears to be a rubber shock isolator there.
I doubt I'll remove that now, but thanks for the tip.

I am amazed at how much this engine vibrates.  Regardless of engine mounts,
I would expect any properly tuned engine to run more smoothly, but I am
inexperienced in diesel engines.  Can you offer an opinion?  Should a
4-cylinder diesel engine vibrate badly?

I suppose anything would vibrate at its resonant frequency.  I suppose that
even a V-8 gasoline engine should vibrate, if its idle rate were low enough.

The vibration decreases DRAMATICALLY as soon as the engine speed is raised a
little bit.  There is an obvious resonance phenomenon at work, here.

I suppose, if the shock isolators are dead, then there is nothing to dampen
vibration.

I have a CDROM describing some mechanical features of this '80 240D, and
quite a number of other models.  I notice that a more expensive auto model,
the 1985 300D, has two "engine shock absorbers."  There is no picture, but I
expect these resemble fluid-type shock absorbers common to all automobile
suspension systems. This tells me that 4-cylinder diesel engines naturally
vibrate, and various shock-absorption methods are employed to dampen the
effect on passenger comfort.  I have never heard of anything like this on
the 4-, 6-, and 8-cylinder gasoline engines I have worked on during my
lifetime.

Any comments welcome.

Thanks.

The dimmer one also resets the trip meter when you push it in, and the
other one sets the clock when you push it in and turn it.  ...or so it
is on my '79.

Probably.  You can look in the engine compartment, it goes through the
firewall and arcs in toward the STOP lever, connecting to that linkage
just below where STOP is printed.  You could fiddle with it on that end,
to see if anything is obviously wrong there.

-tom!

--

that is the idle control.   It only moves ~180 degrees on mine.  I do
have the orig owners manual I can check if you need any info