Combustion Rings May Fail on Certain C175 Off-Highway Truck Engines {1214, 1439, 1718} Caterpillar

Off-Highway Truck/Tractor

793F (S/N: SND1-UP; SSP1-UP; SXP1-UP; D3T1-UP; RBT1-UP)

794 AC (S/N: MN51-UP; MT51-UP)

795F AC (S/N: ERM1-UP)

795FAC XQ (S/N: SNT1-UP)

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

Introduction

The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.

Problem

A combustion ring failure can result in an exhaust leak, external coolant leak, oil leak, or coolant leaking into the cylinder. A combustion ring failure is typically caused by an over-pressurization in the cylinder. There are multiple issues that can cause an over-pressurization event such as electrical wiring issues, fuel system contamination, injection timing issues, and fluid in the cylinder.

Solution

To mitigate risk of combustion ring failures, if any of the codes below are logged or active, Caterpillar recommends taking action at the first available stoppage to investigate and resolve the issue.

• 190-8 Primary Speed Sensor Abnormal Signal

• 1797-3 Rail Pressure Sensor Voltage Above Normal

• 1797-4 Rail Pressure Sensor Voltage Below Normal

Note: A new rail pressure sensor is available and can be applied. Refer to M0081293 for additional information on the new sensor.

Investigate both sensors and wiring to ensure that all harnesses, sensors, and connections are in good working order.