Perkins wont turn over

"Hi
My worst fears are being

"Hi
My worst fears are being realized. Ran My engine (Perkins 4107) about month ago but after it stopped, it would not crank. I removed the starter and had it checked all ok, Bought new 4/O cable and connected direct to battery. I can crank engine by hand on nut at front of pulley. When starter was removed ring gear inspected and looked ok. I can crank engine about 180 degrees with no resistance and then it gets hard to turn. If I crank it back by hand and then try to start it turns to that resistance point. I am thinking of removing injectors to take all compression off engine and then trying to crank. Help and ideas appreciated."

So next day tried to start and

So next day tried to start and by God it started right up. Ran for a while noticed oil pressure only at 20lbs usually at 40. After running for a period oil pressure dropped to zero and I shut it down. Checked oil it had all blew out. Put more oil in and watched as I ran it. It was gushing from behind starter. Took Starer off and saw leak at sump engine gasket. Do you think this leak and not being able to start are related?