C7.1 Engines for Caterpillar Built Machines Caterpillar

Illustration 1	g01363510
Typical example

(1) Top compression ring

The shape of the top compression ring ... Keystone with a barrel face

Width of the top compression ring ... tapered

Ring gap ... 0.30 to 0.45 mm (0.0118 to 0.0177 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 an identification mark which 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 chamfer in the bottom edge with a tapered face

Width of intermediate compression ring ... 2.470 to 2.495 mm (0.0972 to 0.0982 inch)

Clearance between the intermediate compression ring and the piston groove ... 0.065 to 0.110 mm (0.0026 to 0.0043 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 an identification mark which must be on the left of the ring end gap when the top piston ring is installed in an upright piston.

(3) Oil control ring

Shape of oil control ring ... a two-piece coil that is spring loaded

Width of oil control ring ... 2.97 to 2.99 mm (0.1169 to 0.1177 inch)

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

Note: 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 ... 0.41 to 0.55 mm (0.01614 to 0.02165 inch)

Width of top groove in piston ... Tapered

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

Width of third groove in piston ... 3.02 to 3.04 mm (0.1189 to 0.1197 inch)

Piston pin

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

Diameter of the bore for the piston pin ... 39.709 to 39.715 mm (1.56334 to 1.56358 inch)