The Cummins/Onan QSK50 is a 50.3 L 16-cylinder 4-cycle industrial diesel engine rated at 1900 rpm, producing up to 1400 kW. It powers generator sets from Cummins/Onan, including the D-3519, D-3521, DQGAA and DQGAB. It holds 204 L (53.9 gal) of oil and 161 L (42.5 gal) of coolant.
Also known as: Cummins QSK50
Part of the Cummins/Onan QSK50 engine family — 6 variants share parts & fitment.
| Oil capacity | 204.0 L |
|---|---|
| Coolant capacity | 161.0 L |
| Displacement | 50.3 L |
| Cylinders | 16 |
| Aspiration | 4-cycle industrial diesel |
| Rated speed | 1900 rpm |
| Gross power | 1400 kW |
How to read your Cummins/Onan engine serial & model number →
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | — | ||||
| Fuel filter | Fleetguard® ES Filtration, CENTINEL™ | — | |||
| Oil filter | Fleetguard® ES Filtration, CENTINEL™ | — | |||
| Battery | — | ||||
| Belt | — | ||||
| Coolant | CENTINEL Advanced Engine Oil Management System | 4000.0 hours | — | ||
| Oil | Cummins Prelub System | 216.0 U.S. QT | — | ||
| Spark plug | — |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
| Type | Item | Value | Unit | Condition |
|---|---|---|---|---|
| Other | AC waveform THD (THDV) | < 5 | % | no load to full linear load |
| Other | BMEP at set rated load (prime) | 1885 | kPa | prime rating |
| Other | BMEP at set rated load (standby) | 2109 | kPa | standby rating |
| Other | Breaker fail to synchronize default time delay | 120 | s | adjustable 10–900 s |
| Other | Combustion air | 124 | m3/min | prime |
| Other | Combustion air | 130 | m3/min | standby |
| Other | Compression ratio | 15:1 | ||
| Other | Derate above 1402 m (4600 ft) / 40 °C | 4.5% per 305 m (1000 ft) and 11.0% per 10 °C (18 °F) | standby and prime | |
| Other | Exhaust flow at set rated load | 261 | m3/min | prime |
| Other | Exhaust flow at set rated load | 291 | m3/min | standby |
| Other | Frequency regulation | Isochronous | ||
| Other | Governor regulation class | ISO 8528 Part 1 | ||
| Other | Heat rejected, aftercooler circuit | 19 | MJ/min | prime |
| Other | Heat rejected, aftercooler circuit | 21.98 | MJ/min | standby |
| Other | Heat rejected, jacket water circuit | 26.57 | MJ/min | prime |
| Other | Heat rejected, jacket water circuit | 29.89 | MJ/min | standby |
| Other | High AC voltage shutdown default | 110% | % of nominal voltage | for 10 s; adjustable 105–125%, 0.1–10 s |
| Other | Instantaneous pickup (Ii) range (Micrologic 3.0 and 5.0) | 1.5–12 x In | x In | |
| Other | Long-time delay tr | 0.5–24 | s | at 6 x Ir |
| Other | Long-time pickup (Ir) adjustment range | 0.4–1.0 x In | x In | sensor plug rating In |
| Other | Low AC voltage shutdown default | 85% | % of reference voltage | for 10 s; adjustable 50–95%, 2–20 s |
| Other | Max flow rate at max friction head, aftercooler circuit | 537 | L/min | |
| Other | Max flow rate at max friction head, jacket water circuit | 1893 | L/min | |
| Other | Maximum fuel flow | 912 | L/hr | |
| Other | Maximum fuel flow (optional remote radiator) | 469 | L/hr | |
| Other | Maximum static head, aftercooler circuit | 18.3 | m | |
| Other | Maximum static head, jacket water circuit | 18.3 | m | |
| Other | Over frequency shutdown/warning default | 6 | Hz above nominal | for 20 s, disabled; adjustable 2–10 Hz above set point, 1–20 s |
| Other | Over load (kW) warning default | 105% | % of rated kW | adjustment range 80–140%, 0–120 s delay; default 60 s |
| Other | Piston speed | 11.4 | m/s | |
| Other | Random frequency variation | ± 0.25 | % | |
| Other | Regenerative power | 168 | kW | |
| Other | Reverse Var shutdown default | 20% | % of rated Var | for 10 s; adjustable 15–50%, 10–60 s |
| Other | Reverse power shutdown default | 10% | % of standby kW | for 3 s; adjustable 5–20%, 1–15 s |
| Other | Short circuit protection threshold | 175% | % of rating | output current on any phase |
| Other | Telephone Harmonic Factor (THF) | < 3 | ||
| Other | Telephone Influence Factor (TIF) | < 50 | per NEMA MG1-22.43 | |
| Other | Total heat radiated to room | 10.1 | MJ/min | prime |
| Other | Total heat radiated to room | 11.3 | MJ/min | standby |
| Other | Total heat rejection | 52.43 | MJ/min | prime |
| Other | Total heat rejection | 59.88 | MJ/min | standby |
| Other | Under frequency shutdown default | 6 | Hz below reference | for 10 s; adjustable 2–10 Hz below set point, 5–20 s |
| Other | Wire stripping length | 1.38 In (35 mm) | in | |
| Pressure | BMEP at set rated load | 1606 | kPa | prime |
| Pressure | BMEP at set rated load | 1827 | kPa | standby |
| Pressure | Maximum air cleaner restriction | 3.7 | kPa | |
| Pressure | Maximum air cleaner restriction | 6.2 | kPa | |
| Pressure | Maximum back pressure | 6.78 | kPa | |
| Pressure | Maximum back pressure | 6.8 | kPa | exhaust |
| Pressure | Maximum cooling air flow static restriction | 0.12 | kPa | |
| Pressure | Maximum friction head, aftercooler circuit | 48 | kPa | |
| Pressure | Maximum friction head, jacket water circuit | 67 | kPa | |
| Pressure | Maximum fuel inlet restriction | 16.9 | kPa | |
| Pressure | Maximum fuel inlet restriction | 30 | kPa | |
| Pressure | Maximum fuel return line restriction | 34 | kPa | |
| Speed | Overspeed limit | 2100 ±50 | rpm | |
| Speed | Piston speed | 9.5 | m/s | |
| Speed | Rated speed | 1800 | rpm | 60 Hz |
| Temperature | Ambient design (standard set-mounted radiator) | 50 | °C | |
| Temperature | Exhaust temperature | 372 | °C | prime |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Fluid | Grade | Standard | Ambient | Capacity | Notes |
|---|---|---|---|---|---|
| Fuel | ASTM D975 No. 2-D | ASTM D975 | Cetane number: 40-50. 300-500 ppm Sulfur. Fuel inlet temperature 40°C (104°F) reference. |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Code | Name | Meaning | Severity | Action |
|---|---|---|---|---|
| 27 | Low AC voltage shutdown | Voltage on any phase has dropped below a preset value. | Shutdown | Adjustable 50-95% of reference voltage, time delay 2-20 seconds; default 85% for 10 seconds. |
| 32 | Reverse power shutdown | Reverse power detected. | Shutdown | Adjustment range 5-20% of standby kW rating, delay 1-15 seconds; default 10%, 3 seconds. |
| 40 | Reverse Var shutdown | Reverse reactive power detected. | Shutdown | Adjustable 15-50% of rated Var output, delay 10-60 seconds; default 20%, 10 seconds. |
| 46 | Negative sequence overcurrent warning | Excessive imbalances in the three phase load currents and/or power factors. | Warning | Control protects generator from damage due to phase imbalance. |
| 51 | Overcurrent warning/shutdown | Implementation of the thermal damage curve with instantaneous trip level based on CT ratio and application power rating. | Shutdown | AmpSentry protective relay action; see document R1053 time over current curve. |
| 51G | Ground fault overcurrent | Detects a ground fault via external ground fault relay contact input or measured ground current from external CT. | Shutdown | Time delays and thresholds adjustable via InPower or HMI. |
| 59 | High AC voltage shutdown | Output voltage on any phase exceeds preset values; trip time inversely proportional to amount above threshold. | Shutdown | Adjustable 105-125% of nominal voltage, time delay 0.1-10 seconds; default 110% for 10 seconds. |
| 81 u | Under Frequency Shutdown | Genset output frequency cannot be maintained. Adjustable 2-10 Hz below reference governor set point, time delay 5-20 s. Default 6 Hz, 10 s. | Shutdown | |
| 81o | Over frequency shutdown/warning | Genset is operating at a potentially damaging frequency level. | Warning | Adjustable 2-10 Hz above nominal governor set point, 1-20 second delay; default 6 Hz, 20 seconds, disabled. |
| 81u | Under frequency shutdown | Genset output frequency cannot be maintained. | Shutdown | Adjustable 2-10 Hz below reference governor set point, 5-20 second delay; default 6 Hz, 10 seconds. |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Tools: Trip unit test kit
⚠ Wait a minimum of 15 minutes after circuit breaker trips before resetting to allow thermal imaging to reset completely to zero.
Tools: Wire seal MICROTUSEAL
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Voltage | Phase | Connection | Leads | Notes |
|---|---|---|---|---|
| 12470-13800 | 3 | Wye, 3-phase | Winding no. 6062 | Temp rise 125/105/80 °C; ADS-521; feature code B448; max surge kVA 91 |
| 220/380 | 3 | 6 leads | 6 | Winding no. 13; 125°C rise rating 2004 kW / 2505 kVA; stator resistance L-L 0.00102 Ohms; rotor resistance 2.31 Ohms @22°C |
| 240/416 | 3 | 6 leads | 6 | Winding no. 13; 125°C rise rating 2004 kW / 2505 kVA; stator resistance L-L 0.00102 Ohms; rotor resistance 2.31 Ohms @22°C |
| 254/440 | 3 | 6 leads | 6 | Winding no. 312; 125°C rise rating 2000 kW / 2500 kVA; stator resistance L-L 0.00152 Ohms; rotor resistance 2.31 Ohms @22°C |
| 277/480 | 3 | 6 leads | 6 | Winding no. 312; 125°C rise rating 2080 kW / 2600 kVA; stator resistance L-L 0.00152 Ohms; rotor resistance 2.31 Ohms @22°C |
| 277/480 | 3 | Wye, 4 Wire | Feature code R002-2 Voltage-277/480, 3 Phase, Wye, 4 Wire | |
| 346/600 | 3 | 6 leads | 6 | Winding no. 07; 125°C rise rating 2080 kW / 2600 kVA; stator resistance L-L 0.00220 Ohms; rotor resistance 2.31 Ohms @22°C |
| 380 | 3 | Wye, 3-phase | Winding no. 7327 | Temp rise 150/125/105 °C; ADS-335; feature code B595; max surge kVA 312 |
| 380 | 3-phase | Wye, 3-phase | Temp rise 150/105 °C; Duty S/P/C; Max surge kVA 6716; Alternator data sheet ADS-331; Feature Code B595-2 | |
| 4160 | 3 | Wye, 3-phase | Winding no. 6307 | Temp rise 125/105/80 °C; ADS-324; feature code B467; max surge kVA 51 |
| 4160 | 3-phase | Wye, 3-phase | Temp rise 105 °C; Duty P; Max surge kVA 6204; Alternator data sheet ADS-322; Feature Code B312-2 | |
| 440 | 3-phase | Wye, 3-phase | Temp rise 80 °C; Duty P; Max surge kVA 5521; Alternator data sheet ADS-330; Feature Code B689-2 | |
| 480 | 3 | Wye, 3-phase | Winding no. 7361 | Temp rise 125/105/80 °C; ADS-333; feature code B462; max surge kVA 312 |
| 480 | 3-phase | Wye, 3-phase | Temp rise 125/105 °C; Duty S/P; Max surge kVA 5521; Alternator data sheet ADS-330; Feature Code B276-2 | |
| 600 | 3 | Wye, 3-phase | Winding no. 7361 | Temp rise 125/105/80 °C; ADS-333; feature code B465; max surge kVA 07 |
| 600 | 3-phase | Wye, 3-phase | Temp rise 125/105 °C; Duty S/P; Max surge kVA 5521; Alternator data sheet ADS-330; Feature Code B602-2 |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Part # | Description | Category |
|---|---|---|
| 140-3230 | Cleaner, Air (Includes Elements - See Ref. No. 25 and 26) | air_filter |
| 140-3963 | Cleaner, Air (Spec A-C Metal) | air_filter |
| 70781N | Element, Primary - Air Cleaner - Nelson - Heavy Duty | air_filter |
| 70782N | Element, Safety - Air Cleaner - Nelson - Heavy Duty | air_filter |
| AF25544 | Element, Primary - Air Cleaner - Fleetguard - Heavy Duty | air_filter |
| AF25545 | Element, Safety - Air Cleaner - Fleetguard - Heavy Duty | air_filter |
| AF2559300 | Air Cleaner replacement element (Nelson), for Air Cleaner Housing 140-3737 | air_filter |
| 149-2792 | Filter, Fuel | fuel_filter |
| 149-2837 | Filter, Fuel | fuel_filter |
| 149-2853 | Filter, Fuel (Triplex Filter) | fuel_filter |
| 543-0088 | Package, Fuel Filter | fuel_filter |
| A030M222 | Filter, Fuel (Triple Filter) | fuel_filter |
| 501-0970-01 | Line, Fuel | hose |
| 503-1705 | Hose, Hump | hose |
| 503-2754-01 | Hose, Oil | hose |
| 503-2754-02 | Hose, Oil | hose |
| 102-1335 | Plug, Oil Drain | other_service |
| 140-1260 | Fitting, Safety Filter | other_service |
| 140-1548 | Indicator, Service | other_service |
| 6794600 | Washer, Sealing | seal |
Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.
The Cummins/Onan QSK50 engine has an oil capacity of 204.0 liters.
The Cummins/Onan QSK50 has a displacement of 50.3 liters with 16 cylinders.
The Cummins/Onan QSK50 powers 12 generator set(s), including Cummins/Onan D-3519, Cummins/Onan D-3521, Cummins/Onan DQGAA, Cummins/Onan DQGAB, Cummins/Onan DQGAG.