AXLE GP 2616255 - Caterpillar

(4GM, 6PN),
3512B (8RM, 6WN),
3516B (6HN, 7RN) Generator Set Engines;
3508B (2BM, 3DM, 7SM),
3512B (7HM, 8EM, 4TN),
3516B (8CN, 8KN, 9AN) Marine EnginesDescription of Change: A new piston crown has replaced the former piston crown. The new piston crown has four vertical oil drain back holes instead of eight scalloped holes found in the former piston crown. The total cross sectional area available to drain oil from the oil ring groove is the same. This change represents a design improvement.Adaptable To: The new 128-9517 Piston Crown Assembly replaces the former 124-9434 Piston Crown Assembly. The former 124-9434 Piston Crown Assembly has been canceled. See illustration 1 showing the new design, and figure 2 showing the former design. The 125-2782 Piston Skirt has not changed.
Illustration 1. Bottom view (A), new 128-9517 Piston Crown Assembly with 4 drainback holes shown with pointers. Cut-away view (B), shows position of new vertical hole (1).
Illustration 2. Bottom view (A), former 124-9434 Piston Crown Assembly with 8 drainback holes shown with pointers, and cut-away view (B) shows position of former scalloped holes.