HomeCummins/OnanCummins/Onan 50.0DDB-9XR

Cummins/Onan 50.0DDB-9XR Generator Set

The Cummins/Onan 50.0DDB-9XR is a 50 kW (62.5 kVA) Diesel (ASTM No.2) standby generator set powered by a John Deere 6329D (300-6329D) engine. It is available at 347/600 V, 60 Hz. It holds about 14.2 L (3.8 gal) of oil and 18.9 L (5.0 gal) of coolant. Starting uses 2 group-2 batteries at 12 V.

50 kW
Standby
5.39 L
Displacement
14.2 L
Oil capacity
0
Document types

How to read your Cummins/Onan serial & model number →

Typical fuel consumption for 50–55 kW Diesel generators →

Compare with other 50–55 kW Diesel generators →

Service parts for the 50.0DDB-9XR

Grouped by system, with how many of each the parts manual calls for.

Air intake

1 required
140-1089Air filtersee priceAmazon

Oil system

1 required

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

FuelDiesel (ASTM No.2)
Frequency60.0 Hz
Standby power50 kW
Standby kVA62
Oil capacity14.2 L
AlternatorUR 3R
Voltage options347/600 V
Power factor0.8
Battery group2H
Battery voltage12 V
Battery quantity2

Engine

John Deere 6329D (300-6329D)
Oil capacity14.2 L
Coolant capacity18.9 L
Displacement5.39 L
Aspirationnaturally aspirated
Rated speed1800 rpm

Maintenance & consumables

for the John Deere 6329D (300-6329D)
ItemSpecCapacityPart #Interval
Air filterElement, Air Cleaner140-1089 Amazon eBay
Fuel filter
Oil filterMust be a bypass typeAR58956 Amazon $22.82 eBay $13.79 KuduParts $23.00
BatteryTwo 6-Volt, 135 A.H., Group 2H, connected in series; SG 1.260 at 80F
BeltAdjust to 3/4 depression with 20 pounds force
CoolantFill with clean soft water; use rust and scale inhibitor; ethylene-glycol base antifreeze if freezing possible5.0 gal
OilSAE 5W below -10F; SAE 10W between -10F and 32F; SAE 30 above 32F; API CD/SD, MIL-L-2104C15.0 qt

Compatible filters for the John Deere 6329D (300-6329D) — cross-referenced via Donaldson. Options to verify against your serial number, not confirmed for this exact unit.

  • Fuel filter: John Deere AR50041 John Deere DQ24057 John Deere R27091 John Deere AR86755 John Deere AT13387

Service intervals

3
ItemActionHoursMonthsNotes
Generator bearingInspect1000 hrWith unit running. Replace every 10,000 hours or two years (prime power); every five years (standby)
Air cleanerClean3 mox1 - or every 3 months, perform more often in extremely dusty conditions
Alternator and fan beltInspect3 mox2 - or every 3 months. Adjust to 3/4 depression with 20 pounds force

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

21
TypeItemValueUnitCondition
OtherAlternator and fan belt deflection3/4inchwith 20 pounds force
OtherCycle cranker crank time15seconds
OtherCycle cranker rest time10seconds
OtherEngine cranking time limit75seconds
OtherExhaust connection pipe size3inches pipe thread
OtherOil pressure buildup time delay12-1/2seconds
PressureLow oil pressure shutdown alarm setting14psi
PressureMaximum permissible exhaust back pressure25inches H2O1.84 inches Hg
PressureNormal engine oil pressure45-65psi
ResistanceBattery electrolyte specific gravity1.280SGat 80°F, full charge
ResistanceBattery electrolyte specific gravity (hot location)1.225SGambient consistently above 90°F
Speed50 Hz rated engine speed1500rpm
Speed60 Hz rated engine speed1800rpm
SpeedEngine speed from frequency30rpmmultiply frequency (Hz) by 30
SpeedGovernor speed regulation3-5%no load to full load
SpeedOverspeed shutdown2100rpm
TemperatureCity water cooled water temperature180-220°F
TemperatureHigh engine temperature alarm setting215°F
TemperatureNormal water temperature (radiator set)180-195°Fafter running 10 minutes under load
TorqueRotating rectifier diode mounting30in. lbor finger tight plus a quarter turn
VoltageAC voltage regulation2%no load to full load, 0.8 P.F.

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

FluidGradeStandardAmbientCapacityNotes
CoolantClean soft water with rust and scale inhibitor; ethylene-glycol base antifreeze for freezing conditions5.0 gallonsNominal capacity 5 gallons, includes radiator; heat exchanger/city water sets also fill with clean soft water
Engine oilSAE 5WAPI CD/SD; MIL-L-2104Cbelow -23°CSingle viscosity, below -10°F (-23°C)
Engine oilSAE 5W20API CC/SE, CC/SD or SD Series 3; MIL-L-46152below -23°CMulti-viscosity, below -10°F (-23°C)
Engine oilSAE 10WAPI CD/SD; MIL-L-2104C-23°C to 0°CSingle viscosity, between -10°F and 32°F
Engine oilSAE 10W30API CC/SE, CC/SD or SD Series 3; MIL-L-46152-23°C to 0°CMulti-viscosity, between -10°F and 32°F
Engine oilNot RecommendedAPI CC/SE, CC/SD or SD Series 3; MIL-L-46152above 0°C12.0 quartsMulti-viscosity not recommended above 32°F (0°C). Oil pan and filter capacity 12 quarts
Engine oilSAE 30API CD/SD; MIL-L-2104Cabove 0°CSingle viscosity, above 32°F (0°C)
FuelASTM No.2 DieselDo not use copper or galvanized lines/fittings; keep fuel clean

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

8
Engine Speed / Governor Adjustment adjustment
  1. Back off the high speed stop screw.
  2. Screw in the low speed adjusting screw until the frequency meter reads 60 Hz (generator on load).
  3. Turn in the high speed adjusting screw until it bottoms; secure the locknuts.
  4. Adjust governor sensitivity (droop) with the external knurled knob at rear of injector pump housing.
Control Box Load Connections (12-lead) installation

⚠ Instructions do not apply to 347/600 (9X) or 120/240 (3R) models; those connections are made at the factory.

  1. Remove either right, left or top panel from control box.
  2. Connect wires T1 through T12 together as shown on panel and Figure 13 for voltage desired.
  3. Open hinged control panel doors. Connect lead from terminal 63 to correct terminal H2, H3, H4, H5 or H6.
  4. Close front panel and secure with 1/4 turn fasteners.
  5. Connect load wires to generator leads.
Battery Electrolyte Dilution for Hot Locations maintenance

⚠ Avoid skin or clothing contact with electrolyte.

Tools: hydrometer, filler bulb

  1. Fully charge the battery.
  2. With battery still on charge, draw off electrolyte above the plates in each cell (do not pour off).
  3. Refill each cell with distilled water to normal level.
  4. Continue charging for 1 hour at a 4 to 6 hour rate.
  5. Test each cell; repeat steps 2-4 until specific gravity is 1.225.
Battery Service and Charging maintenance

⚠ Do not smoke while servicing batteries; lead acid batteries give off explosive gases while being charged.

Tools: hydrometer

  1. Verify cable connections are secure; coat connections with petroleum-based or non-conductive grease.
  2. Check electrolyte level to split ring mark.
  3. Measure specific gravity; should be 1.280 at 80°F.
  4. If distilled water was added or SG is less than 1.280, place batteries on charge until reading reached; do not overcharge.
Out-of-Service Protection (over 30 days) maintenance
  1. Run set until thoroughly warm.
  2. Drain oil from oil base while still warm; refill and attach warning tag stating oil viscosity used.
  3. Remove each injector; pour 1 ounce (two tablespoons) rust inhibitor or SAE #10 oil into each cylinder.
  4. Crank engine over several times; install injectors.
  5. Service air cleaner.
  6. Clean throttle linkage and protect with a clean cloth.
  7. Plug exhaust outlets to prevent moisture, bugs and dirt.
  8. Wipe entire unit; coat rust-susceptible parts with light film of grease or oil.
  9. Disconnect battery and follow standard battery storage procedure.
  10. Provide a suitable cover for the entire unit.
Priming Fuel System maintenance

⚠ If primer lever will not pump, turn engine over with starter to change position of fuel pump drive lobe on camshaft.

  1. Loosen bleed plug on top of fuel filter.
  2. Pump primer lever until a solid stream of fuel, free of air bubbles, flows from bleed plug.
  3. Secure bleed plug.
  4. Loosen inlet fuel line on injector pump.
  5. Operate primer lever on fuel transfer pump until solid fuel flows from inlet line opening.
  6. Secure injector pump fuel inlet line.
  7. Leave fuel transfer pump priming lever at lowest point of stroke.
Starting the Set operation
  1. Verify crankcase filled.
  2. Verify cooling system filled and input solenoid valve open.
  3. Verify batteries charged and connected.
  4. Verify fuel solenoid valve open.
  5. Move run-stop/reset-remote switch to the run position.
  6. Observe oil pressure gauge; normal oil pressure is 45 to 65 psi.
  7. Check DC ammeter (10 to 30 amperes), AC voltmeter and frequency meter.
Stopping the Set operation
  1. Run engine at no load for three to five minutes to reduce and stabilize temperatures.
  2. Move run-stop/reset-remote switch to stop position.

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

VoltagePhaseConnectionLeadsNotes
110/1903T1-T1250 Hz, 151 amperes, W12 tap H3
115/2003T1-T1250 Hz, 142 amperes, W12 tap H4
115/2301T1-T1250 Hz, 216 amperes, W12 tap H6
115/2303T1-T1250 Hz, 125 amperes, W12 tap H6
120/2083T1-T12; L1, L2, L3; L0 neutral60 Hz, 174 amperes, W12 tap H3
120/2401T1-T12; L0 neutral (can be grounded), L1/L2 hot60 Hz, 260 amperes, reference voltage wire (W12) tap H5
120/2403T1-T12; L1, L2, L3; L0 neutral (can be grounded)60 Hz, 151 amperes, W12 tap H5
127/2203T1-T1260 Hz, 164 amperes, W12 tap H4
139/2403T1-T1260 Hz, 151 amperes, W12 tap H5
220/3803T1-T1250 Hz, 76 amperes, W12 tap H3
230/4003T1-T1250 Hz, 72 amperes, W12 tap H4
240/4163T1-T1260 Hz, 87 amperes, W12 tap H3
254/4403T1-T1260 Hz, 82 amperes, W12 tap H4
277/4803T1-T1260 Hz, 75 amperes, W12 tap H5
347/6003factory connected60 Hz, 60 amperes, W12 tap H3; not reconnectible (code 9X)

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 is the power rating of the Cummins/Onan 50.0DDB-9XR?

The Cummins/Onan 50.0DDB-9XR is rated 50 kW standby (62.5 kVA).

Which engine powers the Cummins/Onan 50.0DDB-9XR?

The Cummins/Onan 50.0DDB-9XR is powered by the John Deere 6329D (300-6329D) engine.

What fuel does the Cummins/Onan 50.0DDB-9XR use?

The Cummins/Onan 50.0DDB-9XR runs on Diesel (ASTM No.2).

What's the oil capacity on a Cummins/Onan 50.0DDB-9XR?

The John Deere 6329D (300-6329D) engine in the Cummins/Onan 50.0DDB-9XR has an oil capacity of 14.2 liters.

Which alternator is fitted to the Cummins/Onan 50.0DDB-9XR?

The Cummins/Onan 50.0DDB-9XR uses a UR 3R alternator.

Which oil filter part number does the Cummins/Onan 50.0DDB-9XR take?

The Cummins/Onan 50.0DDB-9XR uses oil filter part number AR58956.

Which fuel filter part number does the Cummins/Onan 50.0DDB-9XR take?

The Cummins/Onan 50.0DDB-9XR uses fuel filter part numbers JOHN DEERE AR50041, JOHN DEERE DQ24057.

What air filter fits the Cummins/Onan 50.0DDB-9XR?

The Cummins/Onan 50.0DDB-9XR uses air filter part number 140-1089.

Troubleshooting

6

Symptoms & remedies

SymptomRemedy
Fault lamp lights and, engine stops cranking after approximately 75 seconds.See engine service manual for troubleshooting fuel system, ignition system, etc. After correcting problem, reset the engine monitor by moving run-stop/reset-remote switch to reset position. Release and return to run position.
Fault lamp lights immediately after engine starts.Check for: a. overspeed condition as engine starts. b. high temperature condition. c. faulty high engine temperature sensor or overspeed switch. d. faulty starter disconnect.
Fault lamp lights after engine is running.Check the following: a. Oil level-engine will shut down after approximately 12-172'seconds if low oil pressure sensor does not open. b. Oil pressure sensor may be defective. c. High engine temperature - caused by low coolant level, faulty thermostat, etc. d. Faulty high engine temperature sensor. e. Faulty starter disconnect.
Fault lamp lights - no fault condition exists.Be certain that no fault condition exists. Disconnect lead 29, 30 and 31 from TB11 inside control box (refer to wiring diagram). If fault lamp still lights with leads disconnected, remove and replace engine monitor plug-in printed circuit board.
Overcrank fault lamp lights and engine stops cranking after approximately 75 seconds.See engine service manual for troubleshooting fuel system, ignition system, etc. After correcting fault, reset monitor by moving run-stop/reset-remote switch to reset position, then to either run or remote to restart engine.
Overcrank fault lamp lights after engine has run for approximately 75 seconds.Replace start-disconnect circuit board.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing. Full Cummins/Onan 50.0DDB-9XR troubleshooting guide (13 entries) →

Parts

52
Part #DescriptionQtySystem
140-1089Element, Air Cleaner1Air filter Amazon eBay
140-1091Cleaner, Air (Includes Element)1Air filter Amazon eBay
150-0717Switch Assembly, Overspeed1Sensor Amazon eBay $99.95
150-1456Bracket and Point Assembly, Overspeed Switch1Sensor Amazon eBay
191-0665Alternator, Charge (Includes Fan)1Alternator Amazon eBay $519.00
191-0732Regulator, Voltage (Part of Alternator)1Avr Amazon eBay
191-1098Pulley, Alternator1Alternator Amazon eBay
193-0104Sender, Water Temperature Gauge1Sensor Amazon eBay
193-0108Sender, Oil Pressure Gauge1Sensor Amazon eBay $119.99
193-0202Sender, Oil Temperature - Optional1Sensor Amazon eBay
193A104Element, Water Temp.1Sensor Amazon eBay
193A108Element, Oil Pressure1Sensor Amazon eBay
303-0170Rheostat, Voltage Adjusting1Avr Amazon eBay
307-1061Relay, Starter Protection1Starter Amazon eBay
309-00641 Spec A through F1Sensor Amazon eBay
309-0178'Switch, Thermostatic - Hi Engine Coolant Temperature1Sensor Amazon eBay $350.00
309-0179'Switch, Thermostatic - Hi Engine Coolant Temperature1Sensor Amazon eBay
309-0256Thermostat (240 volt water jacket heater)1Thermostat eBay
309-0269Switch, Low Engine Temperature (S4)1Sensor Amazon eBay
309-0285Thermostat (120 volt water jacket heater)1Thermostat eBay
309A179Switch, Water Hi-Temp.1Sensor Amazon eBay
309B10Low Oil Pressure Cut off Switch1Sensor Amazon eBay
312-0058Condenser, Alternator1Alternator Amazon eBay
503-0098Hose, Oil Drain - Bulk (Order By The Foot - 3 Feet Required)1Hose Amazon eBay
503-0386Bulk Hose (water jacket heater; order 15 in. and 6 in. lengths)1Hose Amazon eBay
503-0597Hose, Air Cleaner1Hose Amazon eBay
503-0722Hose, Lower Radiator1Hose eBay
503-0723Hose, Upper Radiator1Hose eBay
509-0125Seal, 011- 'O' Ring1Seal Amazon eBay
130-0449Cap, Radiator1Service part / kit Amazon eBay
130-0605Blade, Fan1Service part / kit Amazon eBay
191-1097Motor, Starting1Service part / kit eBay
232-2219Filter Assembly (For SCR Switched Loads) - Optional1Service part / kit Amazon eBay
305-0524Board Assembly, Printed Circuit - Voltage Regulator1Service part / kit Amazon eBay
307-1031Relay, Start Solenoid1Service part / kit Amazon eBay
307-1058Relay (1) Start Disconnect, (1) Ignition1Service part / kit Amazon eBay
309-01691 Begin Spec G 25 261Service part / kit Amazon eBay
315-0342Transformer, Voltage1Service part / kit Amazon eBay
315-0384Reactor Assembly, Commutator1Service part / kit Amazon eBay
320-0431Breaker (2 Amp), Circuit (Exciter)1Service part / kit Amazon eBay
322-0004L8mp Incandescent (12 VDC)1Service part / kit Amazon eBay
322-0128Panel, Control1Service part / kit Amazon eBay
322-0130Red - Lower1Service part / kit Amazon eBay
322-0131Light, Upper Scale1Service part / kit Amazon eBay
333-0052Heater, 1500 Watt (120 volt water jacket heater)1Service part / kit eBay
333-0073Heater, 2000 Watt (240 volt water jacket heater)1Service part / kit eBay
350-0556Resistor1Service part / kit Amazon eBay
358-0015Diode, Negative (Part of Exciter Rotor)3Service part / kit Amazon eBay
358-0016Diode, Positive (Part of Exciter Rotor)3Service part / kit Amazon eBay
363-0054Heatsink, Positive1Service part / kit eBay
363-0055Heatsink, Negative1Service part / kit eBay
504-0028Valve, Radiator Drain1Service part / kit Amazon eBay

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.

Fuel consumption

RatingLoadL/hgal/h
Prime100%3.910.0
Standby100%3.910.0

Available documents

Operator's manual — 944-0302 Onan DDB Operator's and Parts Manual (4-1974) (Onan (Division of Onan/Studebaker Corporation))
Full service, cheapest listings

Priced items from this model's own parts manual.

Oil filter AR58956$13.79
1 priced item$13.79