819110062 Force SCREW (.250-20 x .625)

Circumstances for Changing the Fuel
Caterpillar 3600 Series Heavy Fuel Engines are designed to use heavy fuels for normal operation. However, it is preferable to operate with distillate fuel before stopping the engine for the following circumstances:
Performance of service on fuel system components such as fuel filters and unit injectors
The engine is shut down for an undetermined period of time without circulation of the fuel through the engine.The following definitions will assist operators in determining the circumstances for changing the fuel:General recommendation - Flush the engine fuel system with distillate fuel prior to performing any maintenance on the fuel system. Flush the fuel system with distillate fuel if the engine is shut down for more than 12 hours. If the jacket water heaters are not functional, flush the fuel system with distillate fuel after every engine shut down.Temporary shutdown - The engine is shut down for 12 hours or less. It is not necessary to change the fuel. The engine can be stopped and started with heavy fuel. Jacket water heaters must be operated in order to maintain the temperature of the jacket water at a minimum of 65 °C (149 °F). Continue to circulate heavy fuel through the engine in order to maintain the temperatures of fuel system components for start-up. The fuel must have the correct viscosity and temperature at all times.Extended shutdown - The engine is shut down for more than 12 hours or for an unknown length of time. Flush the engine fuel system with distillate fuel. Unless cold ambient conditions make the use of jacket water heaters necessary, use of jacket water heaters is not required. Shut off the circulation through the fuel system and the module for cooling the unit injector tips. Purge the pressurized air from the air lines and from the starting motor. Lock the air valves to the starting motor in the OFF position. Space heaters for the generator must be operational.Recommendations for Shutdown and Start-up
The use of proper operating practices is important. The following guidelines are recommended:
For generator sets, operate the space heaters when the generator is not operating. This will help to prevent moisture damage to windings. The space heaters can be controlled with a thermostat or a relay.
A lack of proper temperature control can lead to problems with the unit injectors or other fuel system components. Operate the jacket water heaters when the engine is shut down. This will help to maintain proper temperatures for start-up in the cylinder heads, cylinder liners, and fuel system components. Maintain the jacket water temperature to a minimum of 65 °C (149 °F).
Follow the recommended procedures before starting any engine. Incomplete procedures can lead to system malfunctions that do not allow engine operation. See this Operation and Maintenance Manual, "Engine Starting" topic (Operation Section).
Prior to starting any engine after an overhaul or after servicing the fuel system, ensure that all of the engine protective devices will function. Prepare to use the emergency stop button, if necessary.
Test the engine with distillate fuel after an overhaul or after servicing the fuel system. Perform the test before changing to heavy fuel. If an unexpected problem occurs, distillate fuel is easier to clean up. For example, if a leak develops after starting, cleaning up heavy fuel oil would be more difficult than cleaning up distillate fuel.Fuel Bypass Valve
During normal operation, the valves for the fuel supply lines and the fuel return lines are open. The bypass valve between the supply lines and return lines is closed. When the fuel supply lines and the fuel return lines are closed, fuel does not flow to the fuel filters. The filters will cool. Hours may be required for heating the fuel filters before starting the engine. When the fuel to an engine is changed, the bypass valve must be adjusted in order to maintain the correct fuel system pressure. Adjustment of the bypass valve also maintains the circulation of fuel through the fuel system when the fuel supply and return lines are closed.For sites with more than one engine sharing one fuel oil conditioning module, the fuel pressure to any operating engine will increase when another engine is shut down. When the fuel to an engine is changed, the bypass valve must be adjusted in order to maintain the correct fuel system pressure to any operating engine. Normal supply pressure from the fuel oil conditioning module is 6.5 to 7 bars. This pressure is needed in order to maintain a pressure of 550 to 620 kPa (80 to 90 psi) to any operating engine.Changing the Fuel
The method that is used for changing the fuel depends on the equipment that is used. Different sites may have different equipment. The following methods are possible:
The fuel system can be flushed through the use of auxiliary fuel pump, a separate fuel tank, and fuel lines.
The fuel supply can be switched through the use of a dual source of fuel at the fuel oil conditioning module.A motorized three-way valve with a clock timer is recommended for changing the fuel. This valve can be used with a single engine and with sites that have more than one engine sharing one fuel oil conditioning module. The fuel can be changed during engine operation or after stopping.Changeover From Heavy Fuel Oil To Distillate Fuel During Engine Operation
The preheat temperature for pure distillate fuel must not exceed 60 °C (140 °F). At temperatures above 60 °C (140 °F), distillate fuel loses the lubricating properties. Operating an engine on fuel with insufficient lubricity can damage the unit injectors.
To prevent excessive injection pressures when the fuel is changed to heavy fuel oil, the engine must not be operated at more than 75 percent of rated load.
Operate the engine at reduced load.
Set the timer for the three-way valve to 45 to 50 minutes.
Make sure that all of the valves from the distillate fuel line to the fuel booster module are OPEN.
Change the fuel selector switch on the control box for the fuel booster module from heavy fuel oil to distillate