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Table of Contents
- 1 Table of Contents
- 2 General Information
- 3 Specifications
- 4 Dimensions and Clearances
- 5 Assembly Torques and Special Tools
- 6 Engine Troubleshooting
- 7 Service and Maintenance
- 8 Exhaust System
- 9 Cooling System
- 10 Fuel System
- 11 Governor System
- 12 Oilsystem
- 13 Starting System
- 14 Engine Disassembly
- Download this manual
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Table of Contents
Related Manuals for Onan MDJC
Summarization of Contents
General Information
INTRODUCTION
Manual overview, purpose, and use of sections.
ENGINE MODEL REFERENCE
How to identify and interpret engine model and specification numbers.
Assembly Torques and Special Tools
SPECIAL TOOLS
List of specialized tools available from Onan for service.
Service and Maintenance
PRE-STARTING
Preparations before initial and additional engine starts.
Recommended Fuel
Guidelines for selecting and using diesel fuel types.
Bleeding Fuel System
Procedure for bleeding air from the fuel system.
PRE-HEATING AND STARTING
Procedures for preheating and starting the engine in various conditions.
IF ENGINE FAILS TO START
Procedure and checks when the engine fails to start.
VENTILATION
EXHAUST
Requirements for piping exhaust gases outside and avoiding bends.
BATTERIES
Maintenance checks for starting batteries, connections, and electrolyte.
DUST AND DIRT
Procedures for keeping the engine clean from external contaminants.
HIGH ALTITUDE
Effect of altitude on engine power output.
OIL FILTER CHANGE
OIL DRAIN EXTENSION
Procedure for installing an oil drain extension for service convenience.
OUT-OF-SERVICE PROTECTION
Returning a Unit to Service
Steps for preparing an engine after a period of storage.
Cooling System
INSPECTION
Standard maintenance checks for the entire cooling system components.
IMPORTANCE OF REGULAR MAINTENANCE
Guidelines for yearly cleaning and flushing of the cooling system.
DRAINING COOLING SYSTEM
Procedures for opening drains and removing plugs to drain the system.
CLEANING AND FLUSHING THE COOLING SYSTEM
FILLING COOLING SYSTEM
Procedure for filling the system with a 50/50 antifreeze and water mixture.
MARINE COOLING SYSTEMS
Heat Exchanger Filling
Steps for filling the heat exchanger with coolant to prevent overheating.
Heat Exchanger Cooling System
Explanation of how heat exchanger cooling systems work.
Keel Cooling System (Or Skin Cooling)
Description of keel cooling systems attached to the boat hull.
Direct Cooling System
Description of direct sea water cooling systems used in marine applications.
TYPICAL INSTALLATIONS
WATER FLOW
Checking water flow in marine cooling systems for adequate cooling.
Sea Water
Requirements for continuous sea water flow and cleaning filter screens.
WATER COOLED EXHAUST
Design of marine exhaust systems for heat dissipation and water injection.
SIPHON BREAK
HEAT EXCHANGERS
Information on front and side mount types and their components.
Sea Water Side
Inspection and cleaning of heat exchanger sea water side and zinc pencils.
KEEL COOLERS
Option for DJ-series generator sets, including installation and maintenance.
MARINE WATER PUMPS
Captive Water Pump
Checking captive water pump for wear, leakage, and shaft seal.
Sea Water Pump
Checking sea water pump for shaft seal leakage and impeller condition.
THERMOSTAT
Testing
Procedure to test thermostats for proper opening and closing.
Fuel System
FUEL RECOMMENDATIONS
Guidelines for selecting and using good quality diesel fuel.
FUEL SYSTEM
Components of the fuel system and how fuel is delivered.
FILTER SYSTEM
Description of sediment bowl, primary, and secondary fuel filters.
Nozzle Spray Pattern
Injection Nozzle Tester
Procedure for testing and adjusting injection nozzles with a tester.
NOZZLE REPAIR
NOZZLE INSTALLATION
Steps for cleaning mounting surfaces and installing injection nozzles.
FUEL SOLENOID
Description and function of the fuel shutoff solenoid.
FUEL INJECTION PUMPS
Details on American Bosch fuel injection pumps used on DJ series.
Method 1-Timing by Calculation
Method 2-Flow Timing Injection Pump
Procedure for timing injection pump using flow method when dimensions are lost.
SHIM SELECTION
PSU OR MODEL 50 INJECTION PUMP
Description of PSU or Model 50 pumps used on 2- and 4-cylinder engines.
Pump Cutaway View
Metering Sleeve Operation
Explanation of how the metering sleeve controls fuel delivery.
Delivery Valve Function
TIMING BUTTON CODE
Information on timing button codes corresponding to dimensions.
TIMING BUTTON THICKNESS
Procedure for determining the correct timing button thickness.
TIMING PSU OR MODEL 50 INJECTION PUMPS
Method 1-Timing by Calculation
Procedure for calculating timing button thickness using dimensions.
Method 2-Flow Timing Injection Pump
Procedure for timing using flow method when dimensions are lost.
BRYCE/KIKI FUEL SYSTEM
Nozzles
Information on Diesel Kiki or C.A.C. throttling-pintle type nozzles.
High Pressure Injection Lines
Guidelines for installing high pressure fuel lines.
Bleeding Fuel System
Procedure for bleeding air from the fuel system.
BRYCE/KIKI FUEL INJECTION PUMPS
INJECTION PUMP ADAPTER
Description of the adapter assembly for mounting the injection pump.
Removal
INJECTION PUMP ADAPTER
Procedure for cleaning and preparing the adapter assembly.
TIMING PSU OR MODEL 50 INJECTION PUMPS
Installation
Steps for installing the injection pump onto the adapter assembly.
Torque Instructions
Specific torque values for Bryce/Kiki injection systems.
TROUBLESHOOTING PUMP PROBLEMS
Visual Check
Inspecting nozzle valve, pintle, and body for damage or carbon.
Slide Test
Procedure to check nozzle valve seating using diesel fuel or test oil.
THROTTLING PINTLE NOZZLE TESTS
Tests for nozzle conditions using a manually operated test stand.
OPENING PRESSURE
Leakage Test
Procedure to check for fuel leaks from the nozzle tip.
Chatter Test
Testing nozzle operation by listening for a chattering sound.
SPRAY PATTERN
Assessing the spray pattern for compact and atomized fuel delivery.
Testing Nozzles with Hand Operated Tester
KIKI NOZZLE ADJUSTMENT
Adjusting opening pressure for Kiki type nozzles.
YANMAR-AMERICAN BOSCH NOZZLE ADJUSTMENT
Adjusting opening pressure for Yanmar/American Bosch nozzles.
BLEEDING FUEL SYSTEM
PREHEATING CIRCUIT
Description of the 12-volt circuit for manifold heaters and glow plugs.
Governor System
GOVERNORS
How constant-speed governors maintain engine speed.
Maintenance
Periodic lubrication and inspection of governor linkage.
Adjustments (MDJB, MDJC, MDJE, and MDJF)
Procedures for adjusting governed speed and sensitivity.
Sensitivity Adjustment (Begin Spec R)
MDJA Governor System
Adjusting speed and sensitivity on MDJA engines.
Oil System
OIL PUMP
Description of the oil pump, its mounting, and drive.
LOW OIL PRESSURE CUT-OFF SWITCH
CENTRIFUGAL SWITCH
Description and adjustment of the centrifugal switch for oil pressure.
CRANKCASE BREATHER
PULSATION DAMPER
Function of pulsation damper in reducing intake manifold pulsations.
Starting System
MAINTENANCE
Periodic checks of the starting circuit wiring and starter components.
TESTING
Troubleshooting poor cranking performance related to motor, battery, or circuit.
Armature
Field Coils
Checking field coils for grounding or open circuit.
Bearings
Procedure for replacing worn bearings in the starting motor.
Brushes
Checking brushes for wear, seating, and tension.
Over-Running Clutch
Cleaning and checking the over-running clutch for proper operation.
Shifting Solenoid
Checking continuity of solenoid coils and plunger movement.
PRESTOLITE STARTER REMOVAL AND DISASSEMBLY
PRESTOLITE STARTER ASSEMBLY
Reassembly procedure for the Prestolite starter motor.
MITSUBISHI STARTER REMOVAL AND INSTALLATION
MITSUBISHI STARTER DISASSEMBLY
Steps for disassembling the Mitsubishi starter motor.
Lever Assembly Installation
Pinion Gear Installation
Installing pinion gear and stop ring onto the pinion shaft.
Pinion Gap Adjustment
Adjusting pinion gap by changing fiber washers on solenoid mounting.
Engine Disassembly
ENGINE REBUILDING
General considerations for engine disassembly and rebuilding.
Disassembly
Suggested order for disassembling engine components.
Assembly
General steps and considerations for engine assembly.
ASSEMBLY SUGGESTIONS (Things to Keep in Mind During Engine Assembly)
Tips and special tools for engine assembly.
TESTING AND ADJUSTING ENGINES
Preparation
Checks before testing and adjusting the engine.
Maintenance
Regular maintenance including valve seat cleaning.
Valve Clearance Adjustments
Procedure for adjusting valve clearances on J-series engines.
CYLINDER HEADS, VALVES DISASSEMBLY
Repair
Cleaning and refinishing valves, checking valve guides.
Valve Guides
Checking valve guide to valve clearance and replacement.
Valve Seats
VALVE AND HEAD ASSEMBLY
Procedure for assembling valves, springs, and cylinder heads.
VALVE ROTATOR CLEARANCE
MDJA DECOMPRESSION RELEASE
Adjusting the decompression release mechanism on MDJA engines.
INTERNAL DISASSEMBLY
FLYWHEEL
Removal, replacement, and timing mark procedures for the flywheel.
REPLACEMENT
Flywheel replacement and timing mark determination.
Ring Gear
Procedure for removing and installing the flywheel ring gear.
GEAR COVER
Removal of the gear cover and governor speed-adjustment nut.
Governor Shaft
Removal and replacement of governor shaft and bearings.
Gear Cover Oil Seal
Procedure for replacing the gear cover oil seal.
Assembly, Gear Cover
Assembly steps for the gear cover.
RINGS
CONNECTING RODS
Cleaning and checking connecting rods and bushings.
CONNECTING ROD BEARINGS
Inspecting and replacing connecting rod bearings.
ASSEMBLY AND INSTALLATION
CAMSHAFT
Removal, repair, and installation of the camshaft.
CRANKSHAFT
Removal
Steps for removing the crankshaft.
Inspection
Cleaning and checking crankshaft journals for wear and dimensions.
Crankshaft Grinding
Procedures for machining and shot-peening crankshaft journals.
Main Bearings
Replacing main bearings if clearances are excessive or bearings are worn.
Rear Oil Seal
Procedure for installing a new rear oil seal.
Installation
Steps for installing crankshaft, bearings, and related components.
Crankcase
Break-In Period
Procedures for running in a new or rebuilt engine.
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