C7 Marine Engine Caterpillar

Piston and Rings

Usage:

C7 C7D

Steel Piston

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Illustration 1	g01375097
(6) Connecting rod

(A) Height of the tall piston ... 87.17 ± 0.10 mm (3.432 ± 0.004 inch)

Note: Assemble the rod and steel pistons with the marking "front" on the piston body in the opposite direction of the part number on the rod assembly. Install the rod and piston group in the engine with the part number on the rod assembly to the rear of the engine. The rear of the engine is the flywheel end of the engine. Lubricate the rod and piston group with clean engine oil before you insert the rod and piston group into the block.

(1) Piston body assembly

Lubricate the entire piston in zone (A) prior to assembly into the cylinder block. Use clean unused engine oil.

Piston Rings

Top Ring

(2) The top ring has the mark "UP-1".

Install the piston ring with the side marked "UP-1" toward the top of the piston. The colored stripe faces to the right of the ring end gap.

The ends of the piston ring have a clearance when the piston ring is installed in a cylinder with a specific bore size.

Reference cylinder bore size ... 110 mm (4.3 inch)

Clearance ... 0.40 ± 0.10 mm (0.016 ± 0.004 inch)

The piston ring has an increase in clearance for each 0.03 mm (0.001 inch) increase in the cylinder liner bore.

Increase ... 0.09 mm (0.004 inch)

Intermediate Ring

(3) The intermediate ring has the mark "UP-2".

Install the piston ring with the side marked "UP-2" toward the top of the piston. The colored stripe faces to the right of the piston ring end gap.

Thickness of the new piston ring ... 2.980 ± 0.010 mm (0.1173 ± 0.0004 inch)

The ends of the piston ring have a clearance when the piston ring is installed in a cylinder with a specific bore size.

Cylinder bore size ... 110 mm (4.3 inch)

Clearance ... 0.60 ± 0.10 mm (0.024 ± 0.004 inch)

The intermediate piston ring has an increase in clearance for each 0.03 mm (0.001 inch) increase in the cylinder liner bore.

Increase ... 0.09 mm (0.004 inch)

Oil Piston Ring

(4) The oil piston ring has a spring that is installed with the ring. The gap in the spring should be a distance of 180 degrees from the ring end gap when the oil piston ring is assembled. The light green colored portion of the spring must be visible at the ring end gap.

Thickness of the new piston ring ... 3.985 ± 0.010 mm (0.1569 ± 0.0004 inch)

The ends of the oil piston ring have a clearance when the ring is installed in a cylinder with a specific bore size.

Cylinder bore size ... 110 mm (4.3 inch)

Clearance ... 0.45 ± 0.15 mm (0.018 ± 0.006 inch)

The oil piston ring has an increase in clearance for each 0.03 mm (0.001 inch) increase in the cylinder liner bore.

Increase ... 0.09 mm (0.004 inch)

Note: After the piston rings have been installed, rotate the piston rings so that the end gaps are 120 degrees from each other.