RING-WEAR 8T6744 - Caterpillar

D398 And D399 EnginesReference: Service Magazine, June 24, 1985, Page 9, "New Part Numbers Designate Crankshaft Use".Many marine, marine auxiliary, and petroleum engine customers require marine society approval for their engines. In order for these engines to receive society approval, additional inspection procedures are given to the crankshafts for these engines. To better document and control the procedures, a new part number was released for the marine crankshaft. Now all crankshafts in marine engines receive the necessary certification inspection.
All crankshafts have a shielded "S" stamped on them; however all marine crankshafts have a "K" following the shielded "S".After the crankshafts are given the additional inspection processes, a "K" and a shielded "S" are stamped on the center crankshaft cheek and on the end flanges (see illustration). It is also possible that some of the industrial (part number) crankshafts may have also received this inspection procedure and have a "K" and shielded "S" stamped on the center crankshaft cheek or on the flanges.
End of crankshaft flange (marine engine).Occasionally, industrial or generator set engines are reconfigured for marine use and marine society approval is requested. In order to obtain society approval, the engine crankshaft must be inspected to determine if it has had the necessary inspection processes. If the crankshaft qualifies for certification, it will have a "K" and a shielded "S" stamped on the center cheek or on the flanges. If the crankshaft has these marks, they should be documented by photograph and the crankshaft can qualify for certification. If the engine crankshaft does NOT have a "K" and shielded "S" or a marine engine part number (4W7615 or 4W7719), then the crankshaft must be replaced with a marine crankshaft to obtain society certification.