Series 60 engines currently use two types of pistons. Non-premium engines use pistons with cast iron domes and skirts and open-end connecting rods. Premium engines (identified by the letters “PK” or “BK” in the fifth and sixth positions of the model number) built on or after March 16, 1998 use pistons with forged steel domes, aluminum skirts, and closed-end connecting rods. High torque engines (identified with “FK” or “HK” in the model number) also uses a steel piston, but of a larger diameter (14L).
Note: Steel and cast iron cylinder components must not be mixed in an engine.
The cast iron cross-head piston is a two-piece piston consisting of a dome and a skirt. The dome and skirt are held together by the piston pin. Ring grooves are machined in the piston dome.
| 1. Piston Pin | 5. Oil Ring Expander |
| 2. Piston Skirt | 6. Oil Control Ring |
| 3. Three-piece Bushing | 7. Compression Ring |
| 4. Piston Dome | 8. Fire Ring |
