Loud OM615 noise
 

So I finally got the old gal running (ish anyways). It makes an incredibly loud noise, almost louder than I'd think a rod knock could be. The strange thing is it still develops over 50 pounds of oil pressure. The valves all seemed to adjust good, and compression was consistent across all four cylinders. When I did the compression test it was on a crappy, and half dead battery, and a cold engine. I never got more than a few revolutions out of it per cylinder. All four were right about at 200 psi. I know there's an exhaust leak where the header attaches to the exhaust manifold, but I can't imagine its enough to make that noise. The only thing I can think of is wrist pin. Any other theories? I'm at a loss

I would get a brand new battery and redo the compression test, I doubt the engine will run at all at 200psi. We will need a video to further assess the situation.

I'll see if I can get a video this weekend.