3408 & 3408B DIESEL TRUCK ENGINE Caterpillar


Pistons And Rings

Usage:

Make reference to Guideline For Reusable Parts; Pistons, Form No. SEBF8049; Cylinder Liners, Form No. SEBF8068; and Piston Pins And Retaining Rings, Form No. SEBF8051.

Top And Intermediate Ring

The 8T3150 Keystone Piston Ring Groove Gauge is necessary for measuring ring grooves in keystone style pistons. For correct use of the gauge group, see the instruction card that is with the gauge group.

Install piston rings with "UP" side toward top of piston.

(1) Top ring has the mark "UP-1".

(2) Intermediate ring has the mark "UP-2".

Clearance between ends of piston ring when installed in a cylinder liner with a bore size of 137.16 mm (5.400 in.)

Top ring ... 0.724 ± 0.191 mm (.0285 ± .0075 in.)

Intermediate ring ... 1.080 ± 0.191 mm (.0425 ± .0075 in.)

Increase in clearance between ends of piston rings for each 0.03 mm (.001 in.) increase in cylinder liner bore size ... 0.08 mm (.003 in.)

Oil Control Ring

(3) Install oil control ring with the gap in the spring 180° away from the gap in the ring.

Width of groove in piston for piston ring (new) ... 3.188 ± 0.013 mm (.1255 ± .0005 in.)

Thickness of piston ring (new) ... 3.137 ± 0.013 mm (.1235 ± .0005 in.)

Clearance between groove and piston ring (new) ... 0.051 ± 0.025 mm (.0020 ± .0010 in.)

Maximum permissible clearance (worn) ... 0.15 mm (.006 in.)

Clearance between ends of piston ring when installed in a cylinder liner with a bore size of 137.16 mm (5.400 in.) ... 0.572 ± 0.191 mm (.0225 ± .0075 in.)

Increase in clearance between ends of piston ring for each 0.03 mm (.001 in.) increase in cylinder liner bore size ... 0.08 mm (.003 in.)

Piston Pin Bore

(4) Bore in piston for pin ... 50.815 ± 0.008 mm (2.0006 ± .0003 in.)

Clearance between pin and bore in piston ... 0.008 to 0.028 mm (.0003 to .0011 in.)

Maximum permissible clearance (worn) ... 0.05 mm (.002 in.)

Pin diameter ... 50.795 ± 0.005 mm (1.9998 ± .0002 in.)

Caterpillar Information System:

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