Hi, I am a happy new owner of an "old" '91 300SEL.

The car is fine, but the vacuum system (central locking etc.) needs
quite some care.

I know the previous owner replaced the vacuum pump unit (under rear
seat) recently, but it has already broken again.

It appears that the pump itself was filled with some oily liquid, and
that the rotor of the pump mechanism was physically broken
(splintered), probably because of overload due to the liquid in the
chamber. I looks like the liquid comes from the transparent vacuum
line, which is the manifold vacuum assist line from the vaccum
distribution block and thereby from the vacuum system controlling the
heating and A/C (which does not operate well either).

The car has facelift to W220, and the vaccum control of the headlights
is therefor disconnected. I suspect the leakage may come from there (as
one possibility), and I have ordered a Mityvac to troubleshoot the
complete vacuum system further.

Meanwhile, is there anyone who knows, where the oily substance may come
from?

And not least, does anyone know where to obtain a replacement pump
motor/mechanism (possibly with a worn down motor) or the pump mechanism
itself (instead of the bloody expensive complete unit)?

Thanks in advance.

/Jens (Denmark)

PS: I am new to this group. Please excuse me, if the problem has been
addressed earlier (I couldn't find it in Google)