noisy engine
 

My 1994 Euro C180 with 196000kms is making quite a bit of noise esp when cold and the sounds are coming from the rear of the engine at N. sounds very diesel type noise and sounds like loose things inside or is it normal for this W202 4cyl 1800cc engine? I have been listening to many other car types and they don't sound like this. Sounds more like the whole mech parts inside are actually loose or not running smoothly although I am using Mobil 1 and service only a few months ago. Can my engine be heading for total kaput or need overhaul? If so, can I have the engine changed to the newer version say 1998 onwards with a quieter engine maybe updated, which is cheaper, replace used engine or total overhaul? Trouble is with new engine, maybe needs new other things like harness and maybe ECU too? Give relative cost if possible including labour time involved thanks. The car was wired up to the computer diagnoser, but did not show any codes to link to engine going to collapse.