Loud Tapping, Rough Idle, Had to Tow

[kalikar85]

Last week my 1985 300CD wouldn't start. I determined it was the Neutral Safety Switch. Ive been starting it with a coat hanger, jumping it at the terminal near the battery to get around until I get a new NSS.

I was also chasing an oil leak yesterday and drained some of the oil because I found it was over-filled. I did a diesel purge at this point also to make sure it was healthy and nothing else went wrong in the meantime.

I went to drive it today and it started making a loud clicking noise from the engine and idling shaky. Also, the oil pressure gauge started trembling as it went up which has never happened before.
The clicking noise sounded like metal hitting the crank case from the inside, happens once each rotation (i watched the rotation inside the oil fill), and just gets faster with acceleration.

I tried driving the few miles back home but it persisted and even worsened to the point of it sounding like something metal being tossed around. I had it towed home.

I did a valve adjustment back at home but none were unusually over tight. It was unusually difficult to get the engine to turn over using the power steering bolt. The belt kept slipping on the crankshaft. (In the past the engine turned over more easily by hand.)

Still have to put the valve cover back on and see if its still tapping. Feels like Im in over my head here. What are the possibilities? Broken crankshaft? Chain tensioner spring? Injector? Alternator shaft bearing?

Plz help. Im definitely fearing the worst. How do I diagnose?