Is it oil or water..???

Hi guys..
Greetings to All Experts,
My MB details are 260/2.6 Lit/6 cyl inline/1991/130K/103 engine....
My Mechanic tuned Air/ fuel ratio and cleaned rotor (front of the
engine camshaft.. near white fan).
After that my MB releasing water at exhaust pipe (rear).
Recently Observed at below the engine (center) there is water or oil leak, where engine mounts (on chassis) there is a pipe inside the silver color metal bush.
This water is coming after I drive 20 KM or more...I smell and touch but looks like rust water from old rusty Iron.
No change in radiator water level.
I am not able to conclude what is that water.. From where it coming? is it good / bad symptom...? Is it need any parts replacement or big fix?
please advice... or recommend...
Thanks in advance.
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