AD 51-26-03

51-26-03 CONTINENTAL: Applies to All Continental Model E185 Engines Serially Numbered 2600 and Below Which Have Not Been Major Overhauled Since November 1, 1947, by Continental Motor Corp., or July 1, 1948, by Field Overhaul Agencies. To be accomplished as soon as possible, but not later than January 1, 1952. To preclude valve failures as caused by partially deflated hydraulic valve lifters, the engine must be inspected and modified, if necessary, to assure proper oil flow to the lifters and zero valve lash under all operating conditions. This will require either a partial engine disassembly or a special test as outlined below: (1) Partial Disassembly Method: Remove the cylinders and the hydraulic units of the valve lifters. Check each valve lifter guide bore for proper position of the oil feed hole. (2) Special Test (Alternate Method): By application of air pressure to the crankcase oil galley lines after removal of each rocker arm, determine the number of degrees of crankshaft rotation that the oil groove on each valve lifter in registration with the oil feed hole. A minimum of 145 degrees registration is required. If any oil feed hole is shown by the method chosen to be drilled incorrectly, the end of the hole must be enlarged. As lack of oil flow to the rocker boxes also can result in valve mechanism malfunctioning, the diameter of the pushrod holes should be checked. If 1/32-inch diameter replace with push rods incorporating 1/16-inch diameter holes. (Continental Motors Corp. Service Bulletins Numbers M48-12 and M51-2, Supp. No. 1, cover this same subject and describe both of the above compliance methods.) This supersedes AD 51-08-01.