52035 Mercury LOCK RING, PISTON PIN

Recommended Actions
Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.Diagnostic Codes and Event Codes
Certain diagnostic codes and/or event codes may cause poor performance. Connect the Caterpillar Electronic Technician (Cat ET) and check for active codes and/or logged codes. Troubleshoot any codes that are present before continuing with this procedure.Injector Trim Codes
If any of the injectors or the electronic control module have been replaced, ensure that the injector trim codes have been reprogrammed to the correct values. Refer to Troubleshooting, "System Configuration Parameters" for additional information.Starting Aids
Cold Mode
Use Cat ET to verify that the engine has exited cold mode. If the engine is operating in cold mode, an indicator will be displayed on the top of any of the status screens on Cat ET. Cold mode operation may slow throttle response.Air Inlet Heater (If Equipped)
Ensure that the air inlet heater is programmed to "On". Ensure that the air inlet heater is functioning properly. Refer to Troubleshooting, "Air Inlet Heater Circuit - Test" for additional information.Oil Grade Plugs (If Equipped)
Ensure that the correct oil grade plug is installed. Refer to Operation and Maintenance Manual, "Engine Oil and Filter - Change" for additional information.Throttle Signal
Monitor the throttle signal on Cat ET. Verify that the throttle is operating correctly. Refer to Troubleshooting, "Throttle Position Sensor Circuit - Test" for additional information.Electrical Connectors
Check the J1/P1 ECM connector, the J2/P2 ECM connector, the J300/P300 unit injector connector, the connectors for the throttle position sensor, and the associated wiring for damage, abrasion, corrosion, or incorrect attachment. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information.Unit Injectors
Perform the Injector Solenoid Test on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
Perform the Cylinder Cutout Test on Cat ET in order to identify any injectors that might be misfiring. Refer to Troubleshooting, "Injector Solenoid Circuit - Test" for the proper procedure.Injection Actuation Pressure
Check the engine oil level. Engine oil is used to activate the high pressure hydraulic pump.
Ensure that the engine oil meets the recommendations. Refer to Operation and Maintenance Manual for additional information.
Crank the engine and monitor the injection actuation pressure and the output of the injection actuation pressure control valve. The high pressure oil system is operating properly if the pressure output is a minimum of 6 MPa (870 psi).Fuel Supply
Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.
Check the fuel tank for foreign objects which may block the fuel supply.
Check for air in the low pressure fuel supply system if any of the following procedures have been performed:
Replacement of the fuel filters
Service on the low pressure fuel supply circuit
Replacement of unit injectorsNote: A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel. Refer to Testing and Adjusting for more information.
Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.
Purge air from the low pressure fuel supply circuit. Refer to Operation and Maintenance Manual, "Fuel System - Prime" for the correct procedure.
Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Special Instruction, SEBD0717, "Diesel Fuels And Your Engine".
Check the fuel pressure after the fuel filter while the engine is being cranked. Refer to Testing and Adjusting for the correct pressure values. If the fuel pressure is low, replace the fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve. Refer to Testing and Adjusting for more information.Turbocharger Outlet Pressure Sensor
Monitor "Fuel Position", "Rated Fuel Limit", and "FRC Fuel Limit" on the Cat ET status screen while the engine is operating under full load. These parameters should reflect the information below.
Table 1
"Fuel Position"="Rated Fuel Limit"    
"AND"    
"Fuel Position"<"FRC Fuel Limit"    If "Fuel Position" equals "Rated Fuel Limit" and "Fuel Position" is less than "FRC Fuel Limit", the electronics are operating properly. Otherwise, proceed with the next step.
Monitor the status of "Turbo Outlet Pressure", "Boost Pressure", and "Atmospheric Pressure" while the engine is operating under full load.
Monitor the status of"Turbo Outlet Pressure", "Boost Pressure", and "Atmospheric Pressure" while the engine is operating at low idle.
Turn the keyswitch to the OFF position. The engine should be off. Turn the keyswitch to the ON position.
Monitor the status of "Turbo Outlet Pressure", "Boost Pressure", and "Atmospheric Pressure" for normal operation on Cat ET. When the engine is not running, "Turbo Outlet Pressure" should be equal to "Atmospheric Pressure". When the engine is not running, "Boost Pressure" should be 0 kPa (0 psi).Air Inlet and Exhaust System
Check for an air filter restriction. Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual for additional information.
Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Testing and Adjusting, "Air Inlet and Exhaust System" for additional information.