Camshaft Thrust Washer Torque on C175-20 Off-Highway Truck Engines {1210} Caterpillar

Off-Highway Truck:

797B (S/N: JSM1-UP)

797F (S/N: LAJ1-UP; WSP1-UP)

Introduction

Caterpillar is aware of the issue, but there is not a solution at this time.

Problem

A new 417-5558 Camshaft Gp began production on new C175-20 engine builds on 01October 2012. The new camshaft group modified the thrust washer mounting bolts from a hexagonal head bolt to a higher strength 9X-8271 Bolt (12-point). The torque on these bolts was also increased from a standard torque of 55 ± 10 N·m (41 ± 7 lb ft) up to a new special torque of 73 ± 12 N·m (54 ± 9 lb ft). The SIS web documentation was never updated to reflect the 12-point bolt change or the increased torque.

Solution

Any engine that is currently in process of component rebuild should be checked to ensure the 9X-8271 Bolts (12-point) are being utilized and torqued to 73 ± 12 N·m (54 ± 9 lb ft). At this time, Caterpillar does not recommend taking any action on any engine that has already completed component rebuild with high strength 9X-8271 Bolts (12-point) and low assembly torqued of 55 ± 10 N·m (41 ± 7 lb ft). Analysis of the bolted joint is underway to determine if further action will be needed.

This change is effective for the engine serial numbers listed in Table 1.

Illustration 1	g03892468
(1) 9X-8271 Bolts