C3.4B Engines for Caterpillar Built Machines Caterpillar

Illustration 1	g01155119
Typical example

(1) Top compression ring

Width of top compression ring ... 2.068 to 2.097 mm (0.08142 to 0.08256 inch)

Ring gap ... 0.112 to 0.157 mm (0.00441 to 0.00618 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

Width of intermediate compression ring ... 1.970 to 1.990 mm (0.07756 to 0.07835 inch)

The clearance between a new intermediate compression ring and the piston groove in a new piston ... 0.06 to 0.16 mm (0.00236 to 0.00630 inch)

Ring gap ... 0.060 to 0.100 mm (0.00236 to 0.00394 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 ... 2.49 to 2.51 mm (0.09803 to 0.09882 inch)

The clearance between a new oil control ring and the groove in a new piston ... 0.015 to 0.05 mm (0.00059 to 0.00197 inch)

Ring gap ... 0.050 to 0.090 mm (0.00197 to 0.00354 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.

Illustration 2	g02659840
Typical example (4) Piston (5) Cylinder bore

Measure the piston height above the cylinder block. Refer to Systems Operation, Testing and Adjusting, "Piston Height - Inspect" for the correct procedure. Refer to table 1 to select the correct gasket.

Width of top groove in the piston ... 2.21 mm (0.08701 inch)

Width of second groove in new piston ... 2.05 to 2.07 mm (0.08071 to 0.08150 inch)

Width of third groove in new piston ... 2.54 to 2.56 mm (0.10000 to 0.10079 inch)

Piston pin

Diameter of a new piston pin ... 35.996 to 35.999 mm (1.41716 to 1.41728 inch)