C4.4 Engines for Caterpillar Built Machines Caterpillar

Illustration 1	g03120776
Typical example

(1) Top compression ring

The shape of the top compression ring ... Keystone

Ring gap ... 0.25 to 0.35 mm (0.00984 to 0.01378 inch)

Note: When you install a new top compression ring, make sure that the word "TOP" is facing the top of the piston. New top piston rings have a black identification mark. The identification mark must be on the left of the ring end gap when the top piston ring is installed on an upright piston.

(2) Intermediate compression ring

The shape of the intermediate compression ring ... Internal bevel in the bottom edge with a tapered face

Width of intermediate compression ring ... 2.47 to 2.495 mm (0.0972 to 0.0982 inch)

The clearance between a new intermediate compression ring and the piston groove in a new piston ... 0.065 to 0.110 mm (0.00256 to 0.00433 inch)

Ring gap ... 0.65 to 0.85 mm (0.0256 to 0.0335 inch)

Note: When you install a new intermediate compression ring, make sure that the word "TOP" is facing the top of the piston. New intermediate rings have a blue identification mark. The identification mark must be on the left of the ring end gap when the top piston ring is installed on an upright piston.

(3) The oil control ring

Width of oil control ring ... 2.79 to 3.00 mm (0.10984 to 0.11811 inch)

The clearance between a new oil control ring and the groove in a new piston ... 0.05 to 0.10 mm (0.00197 to 0.00394 inch)

Ring gap ... 0.30 to 0.55 mm (0.0118 to 0.0216 inch)

Note: When you install a new oil control ring, make sure that the word "TOP" is facing the top of the piston. New oil control rings have a red identification mark. The identification mark must be on the left of the ring end gap when the top piston ring is installed on an upright piston. The oil control ring is a two-piece ring that is spring loaded. A pin is used in order to hold both ends of the spring of the oil control ring in position. The ends of the spring of the oil control ring must be installed opposite the end gap of the oil control ring.

Note: Ensure that the ring end gaps of the piston rings are spaced 120 degrees from each other.

Piston

Note: An arrow which is marked on the piston crown must be toward the front of the engine.

Piston height above cylinder block ... 0.55 to 0.20 mm (0.02165 to 0.00787 inch)

Width of top groove in the piston ... Tapered

Width of second groove in new piston ... 2.56 to 2.58 mm (0.1008 to 0.1016 inch)

Width of third groove in new piston ... 3.05 to 3.07 mm (0.12008 to 0.12087 inch)

Piston pin

Diameter of a new piston pin ... 39.694 to 39.700 mm (1.5628 to 1.5630 inch)