3406E Truck Engines Caterpillar

Refer to Guideline for Reusable Parts, SEBF8049, "Pistons" and Guideline for Reusable Parts, SEBF8051, "Piston Pins and Retaining Rings".

Illustration 1	g00514913

Thoroughly lubricate the outer surface of the piston and the piston rings with clean engine oil before installation in the cylinder block.

(1) Piston crown assembly

(2) Piston skirt

(3) Top piston ring

Install the top ring with the side marked "UP-1" toward the top of the piston.

When the piston ring is installed in a cylinder liner that has a bore size of 139.66 mm (5.498 inch), the clearance between the ends of the piston ring is the following value. ... 0.50 ± 0.10 mm (0.020 ± 0.004 inch)

(4) Intermediate ring

Install the intermediate ring with the side marked "UP-2" toward the top of the piston.

When the piston ring is installed in a cylinder liner that has a bore size of 139.66 mm (5.498 inch), the clearance between the ends of the piston ring is the following value. ... 0.83 ± 0.15 mm (0.033 ± 0.006 inch)

(5) Oil control ring

The spring ends of the oil control ring should be assembled 180 degrees from the ring end gap.

Width of the groove in a new piston for the oil control ring ... 4.033 ± 0.013 mm (0.1588 ± 0.0005 inch)

Thickness of the new oil control ring ... 3.980 ± 0.010 mm (0.1567 ± 0.0004 inch)

Clearance between the groove and the new oil control ring ... 0.053 ± 0.023 mm (0.0021 ± 0.0009 inch)

Maximum permissible clearance between the groove and the oil control ring after use ... 0.15 mm (0.006 inch)

When the oil control ring is installed in a cylinder liner that has a bore size of 139.66 mm (5.498 inch), the clearance between the ends of the piston ring is the following value. ... 0.450 ± 0.150 mm (0.0177 ± 0.0059 inch)

For each 0.03 mm (0.001 inch) increase in the cylinder liner bore size, the clearance between the ends of the piston ring increases by 0.08 mm (0.003 inch).

Note: The rings should be positioned with the gaps of the rings approximately 120 degrees from each other.

(6) Piston pin bore

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

Bore in the piston crown bearing for the piston pin ... 55.0355 ± 0.0055 mm (2.1667 ± 0.0002 inch)

Bore in the piston skirt for the piston pin ... 55.020 ± 0.005 mm (2.1661 ± 0.0002 inch)

Diameter of the new piston pin ... 55.000 ± 0.005 mm (2.1654 ± 0.0002 inch)

Length of the piston pin ... 113.20 ± 0.15 mm (4.457 ± 0.006 inch)