PIN 1428793 - Caterpillar

3508 (95Y, 68Z),
3512 (49Y, 65Z),
3516 (27Z, 71Z) Industrial;
3508 (6TJ),
3512 (2WK),
3516 (9KF) Locomotive;
3508 (96Y, 69Z),
3512 (50Y, 66Z),
3516 (29Z, 72Z) Marine;
3508 (23Z, 70Z),
3512 (24Z, 67Z),
3516 (25Z, 73Z) Generator SetThe 9Y-4124 Piston Body Assembly was previously manufactured with an anodized layer on the top of the crown and a phosphate-graphite coating on the skirt. The 7C-2431 Piston Body Assembly was previously manufactured with a phosphate-graphite coating on the skirt. The anodized layer is a chemical surface hardening process for aluminum. The phosphate-graphite coating is a dry lubricant.
The purpose of the anodized layer is to protect the combustion bowl against excessive heat and pressure. The purpose of the phosphate-graphite coating is to protect against piston scuffing during the break-in process.
Due to recent structural improvements to the oil galley and the piston crown, the anodized layer is no longer necessary. Field and laboratory data have also demonstrated that there is no need for the phosphate-graphite coating.
The 9Y-4124 Piston Body Assembly is now manufactured without the anodized layer. The 9Y-4124 and 7C-2431 Piston Body Assemblies are now manufactured without the phosphate-graphite coating.
These piston body assemblies are adaptable to the above Caterpillar 3500 Engines. The new 9Y-4124 Piston Body Assembly, without the anodized layer and the phosphate-graphite coating, and the new 7C-2431 Piston Body Assembly, without the phosphate-graphite coating, can be interchanged with the earlier made piston body assemblies that contain these two features. There is no noticeable difference between the coated and uncoated piston body assemblies other than a difference in color. The color difference has no effect on the usability of the piston body assemblies.