COVER AS-ACCESS 4744110 - Caterpillar

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
G3600 Engines with the 204-6114 Piston or with the 240-4641 Piston have had some piston seizures within the 1000 to 34,000 hour range of service. The seizures result in expensive repairs and in downtime for the end user. The seizures have occurred in most regions of the world. These engines have a compression ratio of 9:1. The engines are used in applications for gas compression.Solution
The strategy that is used for applying the engine load is a significant contributor to the seizing of pistons. The main cause is the application of a heavy load before the temperature of the engine oil and the jacket water reaches 50° C (122° F). The Operation and Maintenance Manuals provide temperature requirements for loading of the engines:
Before you apply a load up to 49 percent of the rated load, the minimum temperature of the jacket water is 38 °C (100 °F). The minimum engine oil temperature is 10 °C (50 °F).
Before you apply a load between 50 and 100 percent of the rated load, the minimum temperature of the jacket water is 50 °C (122 °F). The minimum engine oil temperature is 50 °C (122 °F).Recommendations
The following guidelines are recommended for all G3600 Engines.To reduce the chance of a piston seizure, allow the temperature of the jacket water and of the engine oil to stabilize at a minimum of 50 °C (122 °F) before application of a load that is over 50 percent. Allowing the temperature to reach 60 °C (140 °F) will further reduce the chance of piston seizure.Train the operators to monitor the temperatures of the engine oil and of the jacket water. Keep the load to a minimum during the period of engine warmup.For an engine that operates with a programmable logic controller, program the logic for the requirements of the temperatures into the controller.Maintenance of the coolant and of the thermostats is also a critical factor in reducing the risk of piston seizure. If a thermostat fails in the open position, the temperature of the jacket water can become less than the temperature of the engine oil. This action causes a condition with a hot piston in a cooler cylinder. Follow the recommendations for cooling system maintenance in the Operation and Maintenance Manuals.For engines with the ADEM 3 Electronic Control Module, programming the setpoints for the "High Oil to Engine Coolant Differential Temperature" parameter can also reduce the risk of piston seizure.
For the warning level, program the differential temperature to 1° C (33.8° F).
For the shutdown, program the differential temperature to 3° C (37.4° F).