C12 Marine Engines Caterpillar

Illustration 1	g01524159

(1) The piston is symmetrical with a center crater.

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

(2) Top piston ring

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

The ends of the piston ring have a clearance when the piston ring is installed in a cylinder liner with a bore of 130.000 mm (5.1181 inch). Clearance ... 0.4 ± 0.1 mm (0.0157 ± 0.0039 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)

(3) Intermediate piston ring

Install the piston ring with the side marked "UP-2" toward the top of the piston. The two white stripes face to the right of the piston ring end gap.

Width of groove in new piston for intermediate piston ring ... 3.053 ± 0.013 mm (0.1202 ± 0.0005 inch)

Thickness of new intermediate piston ring ... 2.98 ± 0.01 mm (0.1173 ± 0.0004 inch)

Clearance between groove and intermediate piston ring ... 0.05 to 0.096 mm (0.0020 to 0.0038 inch)

The ends of the piston ring have a clearance when the piston ring is installed in a cylinder liner with a bore of 130.000 mm (5.1181 inch). Clearance ... 1 ± 0.125 mm (0.0394 ± 0.0049 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)

(4) Oil control piston ring

The ends of the oil control piston ring should be a distance of 180 degrees from the ring end gap when the oil control piston ring is assembled. The green colored portion of the piston ring must be visible at the ring end gap.

Width of groove in new piston for oil control piston ring ... 4.052 ± 0.012 mm (0.1595 ± 0.0005 inch)

Thickness of new oil control piston ring ... 3.98 ± 0.01 mm (0.1567 ± 0.0004 inch)

Clearance between groove and oil control piston ring ... 0.05 to 0.094 mm (0.0020 to 0.0037 inch)

The ends of the piston ring have a clearance when the piston ring is installed in a cylinder liner with a bore of 130.000 mm (5.1181 inch). Clearance ... 0.45 ± 0.15 mm (0.0177 ± 0.0059 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)

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

Piston pin bore diameter that is in the bearing of the body assembly ... 53.25 ± 0.01 mm (2.0965 ± 0.0004 inch)

Thoroughly lubricate the piston pin with clean engine oil prior to assembly.