898101751 Mercruiser VALVE, Blow-by

Probable Causes
Active engine derate
Throttle signal from the throttle position sensor
Electrical connectors
Low injection actuation pressure
Fuel supplyRecommended Actions
Active Engine Derate
If an active derate occurs, the warning lamp will flash. "Engine Derate" will also appear in the first engine status box on any status screen of Caterpillar Electronic Technician (ET). Verify that the set points for "Derate" that are in the programmable monitoring system have been programmed to the values that are correct. An SPN-FMI code will appear for an active derate on a J1939 receiving device that will display SPN diagnostic codes.Throttle Signal from the Throttle Position Sensor
Verify that the "Top Engine Limit" and "High Idle" are programmed to the values that are correct. Monitor the parameters for the throttle on the Cat ET. Refer to table 1 for the values of the parameters.
Table 1
Throttle Parameters "Desired Engine Speed" "Throttle Position"
"Low Idle" Programmed to "low idle" 0%
"High Idle" Programmed to "high idle" 100% The "Desired Engine Speed" and the "Throttle Position" should increase linearly. Both parameters should increase steadily to the programmed "High Idle". The "Desired Engine Speed" and the "Throttle Position" should decrease linearly. Both parameters should decrease steadily to the programmed "Low Idle". Refer to Troubleshooting, "Throttle Position Sensor Circuit - Test" for additional information.Electrical Connectors
Use Cat ET to check for the CID 168-FMI 02 diagnostic code. If this diagnostic code is logged, refer to Troubleshooting, "Electrical Power Supply Circuit - Test".
Inspect the battery wires from the Electronic Control Module (ECM) back to the battery compartment. Refer to the Electrical System Schematic. Inspect the wires and the power relay. Check the power and ground connections to the ECM. Refer to Troubleshooting, "Electrical Power Supply" for more information. Low 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 of the Operation and Maintenance Manual.
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).
Connect the electronic service tool and check for the CID 164-FMI 11 diagnostic code. If this diagnostic code has been logged recently, refer to Troubleshooting, "Injector Actuation Pressure System-Test".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 the 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.