COUPLING-PERM 4384678 - Caterpillar

of Change: A new oil control piston ring is used in the 3300 Family of Engines. The new ring has narrower rails and increased unit pressure. This allows for better conformability to the cylinder liner walls and inhibits excess oil from reaching the crown of the piston and igniting. The former piston ring had less unit pressure which allowed more oil to bypass and burn, increasing oil consumption and reducing overall efficiency.Adaptable To: The new 7E6047 Piston Ring is a direct replacement for the former 9L6934 Piston Ring which has not been canceled. The new piston ring can be used in both keystone and rectangular ring pistons. No modifications need to be made to the piston groove to use the new rings. This change is effective with 3304 (07Z25068, 12Z35965), and 3306 (08Z54776, 10Z18207, 13Z20739) Vehicular Engines, and 3306B (63Z17804) Truck Engine.