I have a small crack on my block and it looks like it is only leaking small amounts of oil out when running

Years ago I had an engine that threw a rod and cracked the crankcase wall. After repairing the mechanical damage I repaired the crack using JB Weld and drove the car for several years without a problem. When using the JB Weld for this purpose I'd suggest the crack area has to be absolutely, positively, perfectly clean, void of any oil residue. I cleaned the crack area with an old toothbrush and either a spray can of carburetor cleaner or brake cleaner... I forget, but It was some sort of solvent/cleaner. Then I mixed up the JB Weld and forced it into the crack with my finger. I also put a built-up layer over the crack area, extending about an inch all around the crack. Good luck!