Service parts for the 15.0MDJF-3CR
Grouped by system, with how many of each the parts manual calls for.
Air intake
1 requiredFuel system
1 requiredOil system
1 requiredPrices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.
Specifications
| Fuel | diesel |
|---|---|
| Frequency | 60.0 Hz |
| Standby power | 15 kW |
| Oil capacity | 6.2 L |
| Alternator | solid state voltage regulated (4-pole) |
| Voltage options | 125 V, 64 V |
| Phase | 3 |
| Rated current | 15.0 A |
| Power factor | 1 |
| Circuit breaker | 189 A |
| Battery group | 1H |
| Battery voltage | 6 V |
| Battery quantity | 2 |
| Starting system | 12 V DC |
Engine
| Oil capacity | 6.2 L |
|---|---|
| Coolant capacity | 2.0 L |
| Displacement | 2.3 L |
| Aspiration | naturally aspirated |
| Rated speed | 1800 rpm |
Filters & service parts
model family| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | 140-0606 | Amazon eBay | |||
| Fuel filter | 122-0325 | 600 hr | Amazon eBay $75.00 NAPA $35.18 | ||
| Oil filter | 122-0185 | 100 hr | Amazon Amazon eBay $19.55 eBay NAPA $12.88 | ||
| Battery | SAE group 1H, two in series, 12 volt source; 105 amp-hr (spec table lists 120 amp-hr SAE 20-hr nominal) | — | 800 hr | ||
| Belt | 511-0067 | Amazon eBay NAPA $4.76 | |||
| Coolant | Clean alkali-free water plus approved rust inhibitor; anti-freeze if freezing | — | 1200 hr | ||
| Coolant filter | Remove bolt, end cap and gasket at front end of heat exchanger; clean water passages | — | |||
| Oil | API CD/SE or CD/SD; initial fill CC (formerly DM) oil for first 50-100 hours | — | 800 hr | ||
| Spark plug | — | 800 hr |
Compiled from this model's family documentation — may include parts for closely-related variants. Confirm the exact part for your serial number.
Service intervals
28| Item | Action | Hours | Months | Notes |
|---|---|---|---|---|
| Cylinder head bolts and valve clearance | Adjust | 2 hr | First service — Tighten head bolts and adjust valve clearance after first 2 hours on a new or overhauled engine | |
| Exhaust system | Inspect | 8 hr | With plant running, visually and audibly check for leaks | |
| Fuel sediment bowl | Drain | 8 hr | ||
| Fuel supply | Check | 8 hr | ||
| Oil level | Check | 8 hr | Should be at full mark on oil indicator | |
| Unit | Inspect | 8 hr | Operator maintenance schedule | |
| Water level (heat exchanger models) | Check | 8 hr | ||
| Crankcase oil | Change | 100 hr | Dirty conditions - change every 50 operating hours | |
| Crankcase oil | Drain | 50 hr | First service — Drain initial oil after 50 hours while engine is still hot | |
| Governor linkage | Clean | 100 hr | Perform more often in extremely dirty conditions; lubricate old style linkage | |
| Oil filter | Replace | 100 hr | ||
| Battery | Check | 200 hr | Keep electrolyte level above plates | |
| Brushes | Check | 200 hr | Replace collector ring brushes when worn to 5/16 in; commutator brushes when worn to 5/8 in | |
| Commutator | Check | 200 hr | ||
| Fuel system condensation traps | Drain | 200 hr | ||
| Slip rings | Check | 200 hr | Critical maintenance schedule | |
| Generator | Clean | 500 hr | ||
| Rocker box oil line holes | Clean | 500 hr | ||
| Valve clearance | Check | 500 hr | ||
| Water pump (leaks and wear) | Inspect | 500 hr | Replace if necessary | |
| Primary fuel filter | Change | 600 hr | ||
| Secondary fuel filter | Change | 600 hr | Replace with every 5th change of the primary filter | |
| Nozzle opening pressure and spray pattern | Test | 1000 hr | Must be conducted by trained diesel injection equipment personnel | |
| Valves | Adjust | 1000 hr | Grind valves if required | |
| Breather pulsation dampener element | Replace | 2000 hr | ||
| Fuel filters | Change | 2000 hr | ||
| Engine | Other | 5000 hr | General overhaul if required | |
| Zinc pencil (heat exchanger) | Inspect | 2 mo | Replace if deteriorated to less than 1/2 original size |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Service specifications
60| Type | Item | Value | Unit | Condition |
|---|---|---|---|---|
| Clearance | Brush wear limit (replace) | 5/8 | in | |
| Clearance | Camshaft bearing clearance limit | .0012-.0037 | in | |
| Clearance | Camshaft end play (in back position) | .007-.039 | in | |
| Clearance | Clearance, large bearing to crankshaft | .001-.0033 | in | |
| Clearance | Collector ring run-out | 0.002 | in | compared to generator bearing |
| Clearance | Connecting rod large bearing diameter (I.D.) | 2.0615-2.0630 | in | |
| Clearance | Connecting rod small bushing diameter (I.D.) | 0.9903-0.9906 | in | |
| Clearance | Crankshaft connecting rod journal diameter | 2.0597-2.0605 | in | |
| Clearance | Crankshaft end play | .010-.015 | in | |
| Clearance | Crankshaft main bearing clearance (original equipment) | .0030-.0043 | in | |
| Clearance | Crankshaft main bearing journal diameter | 2.2427-2.2435 | in | |
| Clearance | Cylinder diameter limits | 3.4995-3.5005 | in | |
| Clearance | Exhaust valve clearance in guide | .0030-.0050 | in | |
| Clearance | Exhaust valve stem diameter | .3405-.3415 | in | |
| Clearance | Intake valve clearance in guide | .0015-.0030 | in | |
| Clearance | Intake valve stem diameter | .3405-.3410 | in | |
| Clearance | Piston clearance to cylinder wall below oil ring groove | .0055-.0075 | in | measure 90 degrees to pin |
| Clearance | Piston pin clearance | Thumb Push Fit | ||
| Clearance | Starting motor armature end play | .005-.030 | in | |
| Clearance | Starting motor pinion clearance to pinion stop | .070-.120 | in | solenoid plunger bottomed |
| Clearance | Starting motor pinion rest position (pinion housing mounting face to outer edge of pinion) | 1-9/32 to 1-15/32 | in | |
| Clearance | Valve clearance | .020 (0.51), .018 (0.33), .011 (0.28), .016 (0.41), .017 (0.43), .017 (0.43) | inch (mm) | engine at room temperature about 70°F (21°C) |
| Gap | Breaker point gap (MAJ) | 0.022 | inch (0.56 mm) | full separation |
| Gap | Breaker point gap (MCCK) | 0.020 | inch (0.51 mm) | |
| Gap | Centrifugal switch breaker points gap | .040 | in | |
| Gap | Centrifugal switch gap | 0.020 (0.51 mm) | in | |
| Injection timing | Ignition timing (gasoline) | 19 | degrees BTC | 1800 rpm or slower |
| Injection timing | Ignition timing (gasoline) | 25 | degrees BTC | 3600 rpm or faster |
| Injection timing | Injection timing | 17 | degrees BTC | |
| Injection timing | Injection timing | 18 | degrees BTC | |
| Injection timing | Injection timing | 19 | degrees BTC | Later models after Spec P |
| Injection timing | Injection timing | 21 | degrees BTC | Before Spec P |
| Injection timing | PLB pump timing (DJA) | 17 | degrees BTC | |
| Other | Battery charging high rate | 6 to 8 | amps | |
| Other | Battery charging low rate | 2 to 3 | amps | |
| Other | Battery charging rate solid state combined | 5.26 | amps | |
| Other | Battery charging rate solid state high | 3.7 | amps | |
| Other | Battery charging rate solid state low | 1.56 | amps | |
| Other | Bilge blower time delay | 5 | minutes | |
| Other | Cooling water flow | 6 | gallons per minute | after thermostat opens |
| Other | Cranking limiter time | 45 to 90 | seconds | |
| Other | Cylinder bore | 3-1/2 | in | |
| Other | Emergency relay K14 operation time | 15 | seconds | |
| Other | Emergency time delay low oil shutdown | 45 | seconds | |
| Other | Exhaust valve face seat angle | 45 | degrees | |
| Other | Intake valve face seat angle | 42 | degrees | |
| Other | Maximum operation angle MCCK, MDJA, MDJE | 20 | degrees | any direction |
| Other | Maximum operation angle MDJC, MDJF | 30 | degrees | any direction |
| Other | Starting motor brush spring tension | 32-40 | ounces | with new brushes |
| Other | Starting motor no-load test | 10 volts - 80 amps, 5000 rpm Min. | ||
| Other | Starting motor stall torque | 4 volts - 420 amps, 7.8 lbs. ft. Min. | ||
| Pressure | Delivery valve line pressure | 300-600 | psi (2070-4140 kPa) | engine running |
| Pressure | Engine oil pressure | 20 | psi | minimum, pressure-relief valve is not adjustable |
| Pressure | Fuel pump pressure (MDJA) | 5-6 | psi (34.5-41.4 kPa) | at 1800 rpm |
| Pressure | Fuel pump pressure (MDJC, MDJE, MDJF) | 12-14 | psi (83-97 kPa) | at 1800 rpm |
| Pressure | Fuel transfer pump vacuum | 15-18 | inches (25.4-43.4 mm) | at sea level |
| Pressure | Injection line pressure | 1900 | psi (13,110 kPa) | |
| Pressure | Nozzle opening pressure | 1900-1950 | psi (13,110-13,455 kPa) | |
| Pressure | Nozzle opening pressure (Kiki/Yanmar) | 2133-2204 | psi (14707-15196 kPa) | |
| Pressure | Nozzle opening pressure after several hundred hours | 1750 | psi (12,075 kPa) |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Recommended fluids
| Fluid | Grade | Standard | Ambient | Capacity | Notes |
|---|---|---|---|---|---|
| Coolant | Clean, alkali-free water | Add an approved rust inhibitor; anti-freeze if freezing | Closed cooling (heat exchanger) system | ||
| Coolant | antifreeze | Replace annually in captive system | |||
| Engine oil | API CD/SE | Diesel engines; use CC/SE for first fill only (50 hours) | |||
| Engine oil | API SE or SE/CC | Gasoline engines | |||
| Engine oil | CC (formerly DM) | Passing MS Sequence Tests | First fill only (50 to 100 hours) for new or rebuilt J series diesel | ||
| Engine oil | SAE 10W-30, 5W-20, or 10W, 5W-30 | API CD/SE or CD/SD | 0 deg F to 32 deg F | ||
| Engine oil | SAE 30 | API CD/SE or CD/SD (Series 3 Test; MS Sequences IIA and IIIA) | 6.0 U.S. quarts | Above 32 deg F; do not mix brands or grades; plus 1/2 quart for new filter | |
| Engine oil | SAE 5W-20 or 5W-30 | API CD/SE or CD/SD | Third temperature row (label not legible in source) | ||
| Engine oil | SAE 15W-40 or 20W-40 | -10°C to 32°C | J-series water-cooled diesel engines | ||
| Fuel | ASTM 2-D or 1-D | min Cetane 45 | Diesel; use 1-D below 32°F (0°C) | ||
| Fuel | No. 1 diesel | Low sulfur content; pour point at least 10 deg F below lowest expected temperature | When ambient temperature is below 32 deg F, or at all temperatures during long periods of light engine load | ||
| Fuel | No. 2 diesel | Best economy | |||
| Fuel | nonleaded gasoline | Recommended for gasoline engines | |||
| Grease | graphite lubricant | Steel governor ball joints |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Procedures
12Adjust Carburetor adjustment
⚠ Do not force needles against seats.
- Open both needles 1 to 1-1/2 turns off seats.
- Apply full load; turn main fuel screw in until speed drops, then out to normal.
- Remove load; turn idle screw out until speed drops, then in to normal.
Adjust Governor Linkage (Diesel) adjustment
- Loosen locknuts on governor linkage, remove link at one ball joint.
- Position governor arm and fuel control arm fully forward.
- Adjust linkage so both ball joints fit without moving arms.
- Tighten locknuts.
- Release fuel solenoid plunger.
Adjust Valve Clearance (Diesel) adjustment
Tools: feeler gauge, socket wrench
- Turn flywheel to compression stroke for cylinder to adjust.
- Turn flywheel clockwise additional 10 to 45 degrees.
- Loosen locknut to increase clearance, tighten to reduce.
- Use feeler gauge to set proper gap.
- Adjust in firing order 1-2-4-3.
Adjust Valve Tappet (Gasoline) adjustment
Tools: feeler gauge, wrench
- Remove valve covers.
- Crank engine until intake valve opens and closes.
- Continue 1/4 turn until timing marks align.
- Turn adjusting screw to obtain correct clearance.
- Use flat feeler gauge between valve and valve rotator.
Battery Charge Rate Adjustment adjustment
⚠ Avoid overcharging.
Tools: DC ammeter
- Set slide tap on resistor R4 to about 2 amperes charging rate.
- For frequent starts, increase charge rate slightly until battery stays charged.
- Stop engine when readjusting to avoid shorts.
Checking Centrifugal Breaker Points adjustment
Tools: Thickness gauge, Socket wrench, File or fine stone
- Rotate engine crankshaft a few degrees counterclockwise before adjusting points (use socket wrench on flywheel retaining screw).
- Measure gap with a thickness gauge; set gap at .040 in.
- Loosen and move the stationary contact to correct gap.
- Dress slightly burned points smooth with a file or fine stone; replace burned or faulty points.
Checking and Adjusting Valve Clearance adjustment
Tools: Feeler gauge, Socket wrench
- Turn flywheel until cylinder to be adjusted is on compression stroke (socket wrench on flywheel screw hex head).
- Turn flywheel clockwise an additional 10 to 45 degrees so piston is on power stroke with both valves closed.
- Loosen the rocker arm locknut to increase clearance; tighten to reduce clearance.
- Using a feeler gauge, check clearance between rocker arm and valve; set to .017 in intake and .017 in exhaust.
- Always adjust valve clearances in the firing order (1-2-4-3) sequence, rotating flywheel 180 degrees between cylinders.
Governor Sensitivity Adjustment adjustment
⚠ If the governor is too sensitive, a rapid hunting condition occurs.
- Turn the sensitivity adjusting ratchet counterclockwise for more sensitivity (less speed drop at full load).
- Turn clockwise for less sensitivity (more speed drop).
- Adjust for maximum sensitivity without hunting.
- Readjust speed after sensitivity adjustment.
- Secure the lock nut.
Governor Speed Adjustment adjustment
⚠ Excessive droop may be caused by engine misfiring; correct this before adjusting the governor.
Tools: Tachometer or frequency meter
- Change spring tension by turning the governor spring nut.
- Turn nut clockwise (more spring tension) to increase RPM.
- Turn nut counterclockwise to reduce governed speed.
- Hold a tachometer against the flywheel cap screw or use a frequency meter.
- After adjusting, secure the lock nut.
Set Breaker Points (MAJ) adjustment
- Remove flywheel and examine breaker points.
- Adjust gap to .022 inch (0.56 mm) at full separation.
- Loosen screw to shift point set, retighten securely.
Time Ignition (MCCK) adjustment
Tools: continuity light, thickness gauge
- Crank engine to fully open breaker points.
- Loosen locking screws and turn cam to adjust.
- Set point gap to .020 inch (0.51 mm).
- Shift breaker point box to align timing mark.
Time PLB Pump (DJA) adjustment
Tools: depth micrometer
- Install pump tappet in recess, position flywheel on port closing mark.
- Measure distance from mounting pad to tappet center.
- Subtract from 1.670-inch port closing dimension.
- Select correct shims and install pump.
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Voltage reconnection
| Voltage | Phase | Connection | Leads | Notes |
|---|---|---|---|---|
| 12-lead broad range reconnectible alternator | 12 lead | User connects for required voltage and amperage | ||
| X1 to VR21-5 | X1 | for 50 Hertz | ||
| X1 to VR21-6 | X1 | for 60 Hertz | ||
| 120 | 1 | 2-wire | Reconnectible | |
| 120/240 | 1 | 3-wire | Standard connection for MCCK/MDJE/MDJC/MDJF | |
| 240 | 1 | 2-wire | Reconnectible |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Common questions
What size generator is the Cummins/Onan 15.0MDJF-3CR?
The Cummins/Onan 15.0MDJF-3CR is rated 15 kW standby.
Which engine powers the Cummins/Onan 15.0MDJF-3CR?
The Cummins/Onan 15.0MDJF-3CR is powered by the Cummins/Onan MDJF engine.
Is the Cummins/Onan 15.0MDJF-3CR diesel or gas?
The Cummins/Onan 15.0MDJF-3CR runs on diesel.
What is the oil capacity of the Cummins/Onan 15.0MDJF-3CR?
The Cummins/Onan MDJF engine in the Cummins/Onan 15.0MDJF-3CR has an oil capacity of 6.2 liters.
What is the coolant capacity of the Cummins/Onan 15.0MDJF-3CR?
The Cummins/Onan 15.0MDJF-3CR cooling system holds 2 liters (0.5 US gallons) for the engine, per the manufacturer specification sheet.
What voltage does the Cummins/Onan 15.0MDJF-3CR produce?
The Cummins/Onan 15.0MDJF-3CR is offered in 125 V, 64 V, 3-phase.
What size battery does the Cummins/Onan 15.0MDJF-3CR need?
The Cummins/Onan 15.0MDJF-3CR uses 2 batteryies, 6 V each, group 1H, per the manufacturer specification sheet. The starting system is 12 V DC.
What alternator comes on the Cummins/Onan 15.0MDJF-3CR?
The Cummins/Onan 15.0MDJF-3CR uses a solid state voltage regulated alternator. It has 4 poles.
What oil filter fits the Cummins/Onan 15.0MDJF-3CR?
The Cummins/Onan 15.0MDJF-3CR uses oil filter part number 122-0185.
What fuel filter does the Cummins/Onan 15.0MDJF-3CR use?
The Cummins/Onan 15.0MDJF-3CR uses fuel filter part number 122-0325.
What air filter does the Cummins/Onan 15.0MDJF-3CR use?
The Cummins/Onan 15.0MDJF-3CR uses air filter part number 140-0606.
Troubleshooting
6Symptoms & remedies
| Symptom | Cause | Remedy |
|---|---|---|
| Incomplete circuit between exciter and slip rings. | Slip ring brush shunt broken | Check all slip ring brush shunts with an ohmmeter and replace broken brush shunts. |
| Slip ring brushes not contacting the slip rings. | Replace slip ring brush spring which may have come off or broken; or replace brushes which may have become worn down to far to contact the slip rings. | |
| Insulating film on slip rings. | Clean slip rings with stone or fine sandpaper and blow out dust. | |
| Short circuit in field | Dampness or deteriorated insulation. | Bake if damp, repair or replace if insulation is deteriorated. |
| Open circuit in field | Rough usage or original short circuit which may have burned a coil or connection. | Examine field connections and test with ohmmeter. If a coil is open, replace it. |
| No generator output or low output. | Defective shunt field bridge rectifier | Check AC components as listed above and preceding page. Check bridge rectifier with an ohmmeter. Replace if necessary. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing. Full Cummins/Onan 15.0MDJF-3CR troubleshooting guide (15 entries) →
Parts
1| Part # | Description | Qty | System | |
|---|---|---|---|---|
| 305-0264 | Rectifier Assembly, Resistor and Complete (exciter) | 1 | Avr | buy |
Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.
Available documents
Operator's manual — 968-0345 Onan MDJF Operators and Parts Spec A-D (6-1973) (Onan (Onan Division of Onan Corporation))Service manual — 932-0405 Onan Marine Genset MCCK MDJA MDJC MDJE MDJF Training Manual (07-1979) (Cummins/Onan)
This page was generated from the 2 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.