As Webby says. I've stopped drilled exhaust sleeves and cones in the past (A340/CFM56 from memory). Can't remember if that was an approved temp repair in the manual or a "dispensation" with repeat inspections from the technical department based on length & depth of crack, proximity to any frames or fasteners etc.
Would be helpful if we knew if it was piston or jet engine, and actual component with the crack..