I have a 1999 C230 that sat for a couple of years. Put in a new battery, new starter, but it won't start. It barely cranks - sometimes just a click, other times a brief turn but never really a turn-over. All accessories work, windows, lights, etc. The lights dim when i try to start it. Checked connections I could get to, grounds, etc. and fuses and haven't found anything. I don't suspect the starter itself since its new but I checked it anyway and the starter and solenoid and each seems to work (by connecting the positive directly to the solenoid and to the starter terminal (separately) on stater assembly. I don't have a clue what to check next. Once I get it to crank over i'll change all the fluids since it has sat so long, but I haven't been able to get it to crank, no less start. I appreciate any thoughts.

 

Some of the fluids may have gunked up a bit. You might need to prime the fuel line a little bit. Check the engine oil level and if the spark plugs are in good shape. Also, maybe some of the parts aren't well greased up? Do the belts seem like they are in good shape? Does anything seem out of place? I might try adding some new gas first. But you will still have to prime the lines.