3412C Engine Caterpillar

Illustration 1	g00368752

Illustration 2	g00368754
Positioning the piston pin bearing

(1) Bore for piston pin bearing

Dimension ... 55.436 ± 0.013 mm (2.1825 ± 0.0005 inch)

Tight fit between connecting rod eye and piston pin bearing ... 0.05 to 0.10 mm (0.002 to 0.004 inch)

To install the piston pin bearing, the connecting rod must be heated. Do not use a torch to heat the connecting rod.

Maximum temperature for heating of connecting rod ... 177 ° to 260 °C (350 ° to 500 °F)

(A) The bearing junction and the locating hole are angled 180 degrees from each other. The bearing junction and the locating hole must be assembled within area (A).

(X) Tolerance for installation of bearing junction and locating hole ... 5 ± 1 degree

(2) Bore

Bore in the connecting rod bearing after torquing of the connecting rod bolts ... 103.500 ± 0.013 mm (4.0748 ± 0.0005 inch)

(3) Dimension

Distance between center of bearings ... 261.62 ± 0.05 mm (10.300 ± 0.002 inch)

(4) Piston pin

Bore in new bearing for piston pin ... 50.830 ± 0.008 mm (2.0012 ± 0.0003 inch)

Diameter of new piston pin ... 50.795 ± 0.005 mm (1.9998 ± 0.0002 inch)

Maximum clearance between bearing and worn piston pin ... 0.08 mm (0.003 inch)

(5) Crankshaft bearing

Bore in bearing for crankshaft ... 97.119 to 97.175 mm (3.8236 to 3.8258 inch)

Clearance between new bearing and crankshaft ... 0.071 to 0.168 mm (0.0028 to 0.0066 inch)

Maximum clearance between worn bearing and crankshaft ... 0.25 mm (0.010 inch)

Illustration 3	g00368755

(6) Connecting rod nut

The tightening procedure for the connecting rod nut follows:

1. Put clean engine oil on the bolt threads and on the contact surfaces before assembly.

2. Tighten the nuts.

   Torque for nuts ... 82 ± 8 N·m (60 ± 6 lb ft)

3. Place a mark on each nut and on the end of each bolt. Refer to Illustration 3.

4. Additionally tighten each nut.

   Angle (Z) ... 120 ± 5 degrees

Illustration 4	g00786947
Cross section of connecting rod

Note: When the connecting rod and the piston are installed in the engine, make sure that surface (C) is adjacent to the thrust surface of the crank pin. Surface (B) faces the rod that is on the same crank pin. Be sure to install the connecting rod and the piston with this orientation.

Side clearance between two connecting rods on same new crankshaft pin ... 0.28 to 0.84 mm (0.011 to 0.033 inch)