A double action locking jar is operable to provide a jarring force in an upward or downward direction. A pair of pressure pistons form a pressure chamber in which a Belleville spring stack is located. A metering orifice in one of the pistons serves to provide a delay mechanism for release of a mandrel within the housing. Two collets are located within the housing for mechanically releasing the mandrel when a tension or compression force is applied to the mandrel. The jar may be mechanically actuated only by allowing the pistons to freely move within the housing without hydraulic resistance.