Should be on the block, check right behind the alternator on the Block. If not there then check on the datacard that came with the vehicle. You could also try the dealer, as they have a complete record on all the cars from that period.
behind the engine
By this I assume you mean the amount of oil that will fill the engine to the maximum oil guage level when the engine is empty. For the 190E 2.6 it is between 6 and 7 lts (1.5gallons)
By using a tool box open the location and remove it to replace it with a new one
For a 190E 1984 Model, it is about 60Litres, this is 13 Gallons(UK) or 16 Gallons(US). For a 190E 1993 Model it should be the same +/- 5Litres.
There is no filter:)
Where and how do you change the fuse for the dash bord lighting sytem in the 1993 190e 2.3l
well if it has the same engine layout as my 1993 190e in the front of the engine there is a fan, and that fan has a clutch integrated into it, to engage when the engine starts to over heat, and they do wear out which means you can stop the fan with your hand while the engine is running. not recommended to try doing with your fingers.
16 gallons
There is a number on the recoil starter and the back of the engine .
under the sprocket on the left of the motor
my 1993 190E 2.3 is doing the same thing. just replace the switches...they tend to not last
the nmber one spark plug in all way to the right of the engine block with you standing in front of the car.