Mercedes Benz repair: 1983 Mercedes 380 SE wont start, mercedes 380, auto help

Question
It makes a loud clicking noise and the engine does turn, but very slowly and will not turn over. Except for an oil leak it was running ok, maybe a little fast. I added a stop leak product to stop the leak but it did not seem to work. In fact it seemed to work worse, so I parked it over the winter. It would not start without charging the battery, then not at all. I replaced a bad battery but no change.

Answer
What happens if you place a good battery in the car . Turn on the headlights and then crank the vehicle. Do the headlights dim? Go off ? or nothing at all?
It worries me the noise you heard.
I suggest that someone try to manually crank this engine to make sure that the engine has not locked up/
Let Me know
Ralph
Miami Auto Help Inc