Inspection and Repair Procedure to Replace the Studs for the Rocker Arm Shaft{1102} Caterpillar

Articulated Truck:

735 (S/N: B1N1-UP)

740 (S/N: B1P1-UP)

Engine:

C15 (S/N: BXS1-UP; MXS1-UP; NXS1-UP)

Introduction

Read this procedure and understand this procedure completely before attempting any of the repairs that are described within the article.

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Removal Procedure

Remove the rocker arm and shaft. Refer to Disassembly and Assembly, RENR9403, "Rocker Arm and Shaft - Remove" for the serial number prefixes S/N:MXS, and ; S/N:NXS on C15 On-Highway Engines. Refer to Disassembly and Assembly, SENR9693, "Rocker Arm and Shaft - Remove" for the serial number prefix S/N:BXS on C15 On-Highway Engines. Refer to Disassembly and Assembly, RENR8261, "Rocker Arm and Shaft - Remove" for 735 and 740 Articulated Trucks.

Inspection Procedure

1. Fix the indicator and the surface probe to the 90° holding block. Find the area that is unworn between the saddle of the rocker shaft and the rocker arm shaft. Remove the burrs by lightly filing the edges at the top of the saddle on the rocker shaft. Set the indicator on the milled face of the head over the saddle of the rocker shaft. Locate the lowest point of the saddle by moving the block back and forth. Ensure that the block is perpendicular to the axis of the camshaft. Zero the indicator. Move the indicator back and forth in order to recheck the zero. If necessary, reset the indicator to zero.

2. When the indicator is reset, move the indicator to the worn portion of the saddle of the rocker shaft. Again, move the block back and forth in order to make sure that the block is perpendicular to the axis of the camshaft. Record the lowest negative number as the maximum amount of wear. The lowest number will be the lowest point.

3. Repeat the procedure to measure the worn portion of the saddle at both edges of the support for the center of the rocker arm shaft. And measure the worn portion of the saddle at the opposite end of the rocker arm shaft.

   Note: The guideline for replacing the cylinder head for the fretting of the rocker arm shaft is 0.5 mm (0.019 inch) of wear difference. To calculate the wear differences, subtract the wear number of the end of the rocker arm shaft saddle from the wear number for the center support saddle. If the cylinder head is less than 0.5 mm (0.019 inch), the cylinder head is reusable.

Illustration 1	g01284520
Move the gauge back and forth in order to zero the gauge and measure the wear depth.

Illustration 2	g01284619
Places to measure

Installation Procedure

Illustration 3	g01284648

1. Position the rocker arm shaft assembly (4), valve rocker arms (3), and electronic unit injector rocker arms (1) as a unit with the lifting bracket on the cylinder head.

2. Install the bolts and studs (2) .

3. Refer to Disassembly and Assembly, RENR9403, "Rocker Arm and Shaft - Install" for the torque procedure.

Installing the Variable Valve Actuator

1. Refer to Disassembly and Assembly, RENR9403, "Valve Actuator (Variable) - Install" for C15 On-Highway Engines.