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Cummins/Onan QSK23-G7 NR2 Engine

The Cummins/Onan QSK23-G7 NR2 is a 23.15 L 6-cylinder turbocharged and low temperature after-cooled engine rated at 1800 rpm, producing up to 910 kW. It powers generator sets from Cummins/Onan and MQ Power, including the 600 DQCA, 750 DQCB, 800 DQCC and 800DQCC-A034N301. It holds 102 L (26.9 gal) of oil and 109.5 L (28.9 gal) of coolant.

Also known as: Cummins QSK23-G7 NR2

23.15 L
Displacement
6
Cylinders
1800 rpm
Rated speed
910 kW
Gross power

Engine specifications

Oil capacity102.0 L
Coolant capacity109.5 L
Displacement23.15 L
Cylinders6
AspirationTurbocharged and low temperature after-cooled
Rated speed1800 rpm
Gross power910 kW

Common problems

15
  • Over Current 1471
  • Low Coolant Level 197
  • Emergency Stop
    Fix: Annunciated whenever either emergency stop signal is received from external switch.
  • Weak battery warning
    Fix: The control system will test the battery each time the generator set is signaled to start and indicate a warning if the battery indicates impending failure.
  • Weak Battery 1442
  • Under frequency shutdown 81 u
    Fix: Generator set output frequency cannot be maintained. Settings are adjustable from 2-10 Hz below reference governor set point, for a 5-20 second time delay. Default: 6 Hz, 10 seconds. Over frequency shutdown/warning is disabled when excitation is switched off, such as when engine is operating in idle speed mode.
  • Under Frequency 1448
  • Too Long in Idle 2342
  • Speed/Hz Match 1469
  • Speed Signal Lost 121
  • Shutdown After Battle Short 1123
  • Short Circuit 1445
  • Reverse power shutdown
    Fix: Adjustment range: 5
  • Remote Emergency Stop 1434
  • Pre-Low Oil Pressure Sensor 143

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan QSK23-G7 NR2.

Maintenance schedule

ItemSpecCapacityPart #Interval
Air filterDry replaceable element with restriction indicator—500 hr
Fuel filterSpin-on fuel filters with water separator—500 hr
Oil filterFleet guard dual venturi spin-on, combination full flow and bypass filters—500 hr
Battery10Amp, 120/208/240VAC, 12/24V, 50/60HzA048G602500 hr eBay
BeltBelt Driven, Centrifugal—
Coolant-45109.5—
OilOil level is full102.0—
Spark plugnot specified—

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service specifications

60
TypeItemValueUnitCondition
OtherAC waveform THD (THDV)< 5%no load to full linear load
OtherBMEP at set rated load (prime)1885kPaprime rating
OtherBMEP at set rated load (standby)2109kPastandby rating
OtherBreaker fail to synchronize default time delay120sadjustable 10–900 s
OtherCompression ratio16:1
OtherDerate above 1402 m (4600 ft) / 40 °C4.5% per 305 m (1000 ft) and 11.0% per 10 °C (18 °F)standby and prime
OtherHigh AC voltage shutdown default110%% of nominal voltagefor 10 s; adjustable 105–125%, 0.1–10 s
OtherInstantaneous pickup (Ii) range (Micrologic 3.0 and 5.0)1.5–12 x Inx In
OtherLong-time delay tr0.5–24sat 6 x Ir
OtherLong-time pickup (Ir) adjustment range0.4–1.0 x Inx Insensor plug rating In
OtherLow AC voltage shutdown default85%% of reference voltagefor 10 s; adjustable 50–95%, 2–20 s
OtherOver frequency shutdown/warning default6Hz above nominalfor 20 s, disabled; adjustable 2–10 Hz above set point, 1–20 s
OtherOver load (kW) warning default105%% of rated kWadjustment range 80–140%, 0–120 s delay; default 60 s
OtherPiston speed11.4m/s
OtherReverse Var shutdown default20%% of rated Varfor 10 s; adjustable 15–50%, 10–60 s
OtherReverse power shutdown default10%% of standby kWfor 3 s; adjustable 5–20%, 1–15 s
OtherShort circuit protection threshold175%% of ratingoutput current on any phase
OtherTelephone Harmonic Factor (THF)< 3
OtherTelephone Influence Factor (TIF)< 50per NEMA MG1-22.43
OtherUnder frequency shutdown default6Hz below referencefor 10 s; adjustable 2–10 Hz below set point, 5–20 s
OtherWire stripping length1.38 In (35 mm)in
PressureBMEP at set rated load2214kPaprime rating
PressureBMEP at set rated load2435kPastandby rating
PressureMaximum air cleaner restriction6.2kPa
PressureMaximum back pressure10.1kPa
PressureMaximum back pressure6.8kPaexhaust
PressureMaximum cooling air flow static restriction0.12kPa
PressureMaximum fuel inlet restriction13.44kPa
PressureMaximum fuel inlet restriction30kPa
PressureMaximum fuel return line restriction34kPa
SpeedDroop electronic speed governing0 to 10%no load to full load
SpeedFrequency drift+/-0.5%33 °C (60 °F) change in ambient temperature over an 8 hour period
SpeedFrequency regulationIsochronous
SpeedIsochronous governing steady state accuracy+/-0.25%any steady state load from no load to full load
SpeedOver frequency shutdown/warning (81 o) default6Hz20 seconds, disabled
SpeedOverspeed limit2100rpm
SpeedOverspeed limit2100 ±50rpm
SpeedRandom frequency variation± 0.25%
SpeedRandom frequency variation± 0.25%%
SpeedRated speed1800rpm60 Hz
SpeedUnder frequency shutdown (81 u) default6Hz10 seconds
TemperatureAmbient design (standard set-mounted radiator cooling)50°C
TemperatureAmbient design (standard set-mounted radiator)50°C
TemperatureControl operating ambient temperature-40 to +70°C
TemperatureExhaust temperature458°Cprime rating, at set rated load
TemperatureExhaust temperature476°Cstandby rating, at set rated load
TemperatureExhaust temperature at set rated load (prime)463°Cprime
TemperatureExhaust temperature at set rated load (standby)469°Cstandby
TemperatureHMI operating ambient temperature-20 to +70°C
TemperatureMaximum aftercooler inlet temp49°C
TemperatureMaximum fuel inlet temperature71°C
TemperatureMaximum jacket water outlet temp (remote radiator)104°Cstandby
TorqueCircuit breaker terminal tightening torque (AWG 1/0...750 kcmil)548.75 Lbf.In (62 N.m)Lbf.In0.08…0.62 in² (50…400 mm²)
VoltageDigital output voltage regulation+/-1.0%any loads between no load and full load
VoltageDroop voltage regulation0-10%no load to full load
VoltageHigh AC voltage shutdown (59) default110%10 seconds
VoltageLow AC voltage shutdown (27) default85%10 seconds
VoltageRandom voltage variation± 0.5%
VoltageRandom voltage variation± 0.5%%
VoltageStandard temperature rise150°CStandby at 40 °C ambient

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
FuelASTM D975 No. 2-DASTM D975Cetane number: 40-50. 300-500 ppm Sulfur. Fuel inlet temperature 40°C (104°F) reference.
Fuelnumber 2 diesel fuelDirect injection, fuel filter, automatic electric fuel shutoff

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

Fault codes

11
CodeNameMeaningSeverityAction
27Low AC voltage shutdownVoltage on any phase has dropped below a preset value. Adjustable over a range of 50-95% of reference voltage, time delay 2-20 seconds. Default value is 85% for 10 seconds. Function tracks reference voltage.ShutdownAdjustable 50-95% of reference voltage, time delay 2-20 seconds; default 85% for 10 seconds.
32Reverse power shutdownReverse power detected.ShutdownAdjustment range 5-20% of standby kW rating, delay 1-15 seconds; default 10%, 3 seconds.
40Reverse Var shutdownReverse reactive power detected.ShutdownAdjustable 15-50% of rated Var output, delay 10-60 seconds; default 20%, 10 seconds.
46Negative sequence overcurrent warningExcessive imbalances in the three phase load currents and/or power factors.WarningControl protects generator from damage due to phase imbalance.
51Overcurrent warning/shutdownImplementation of the thermal damage curve with instantaneous trip level based on CT ratio and application power rating.ShutdownAmpSentry protective relay action; see document R1053 time over current curve.
51GGround fault overcurrentDetects a ground fault via external ground fault relay contact input or measured ground current from external CT.ShutdownTime delays and thresholds adjustable via InPower or HMI.
59High AC voltage shutdownOutput voltage on any phase exceeds preset values; trip time inversely proportional to amount above threshold.ShutdownAdjustable 105-125% of nominal voltage, time delay 0.1-10 seconds; default 110% for 10 seconds.
81 oOver frequency shutdown/warningGenerator set is operating at a potentially damaging frequency level. Settings are adjustable from 2-10 Hz above nominal governor set point for a 1-20 second time delay. Default: 6 Hz, 20 seconds, disabled.Warning
81 uUnder frequency shutdownGenset 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
81oOver frequency shutdown/warningGenset is operating at a potentially damaging frequency level.WarningAdjustable 2-10 Hz above nominal governor set point, 1-20 second delay; default 6 Hz, 20 seconds, disabled.
81uUnder frequency shutdownGenset output frequency cannot be maintained.ShutdownAdjustable 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.

Procedures

3
Trip Unit Operation Verification diagnostic

Tools: Trip unit test kit

  1. Connect a test kit to the trip unit test plug receptacle.
  2. Perform verification tests per instructions shipped with the test kit to verify trip unit functions.
Battery replacement / battery rack installation maintenance
  1. Isolate DC supply before working on battery connections.
  2. Install battery rack with hold-down, floor standing.
  3. Install battery with minimum 2200 amps capacity at -18 °C to 0 °C.
  4. Verify 24 volt negative ground connection.
Trip Unit Switch Adjustment operation

⚠ 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

  1. Open switch cover.
  2. Adjust the appropriate switches to desired values.
  3. Replace switch cover.
  4. Use wire seal MICROTUSEAL, if necessary, to provide tamper evidence.

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
120/2083Wye12/6Winding 311/312; ADS-631; feature code BC38-2
120/2403Delta12/6Winding 311/312
12470-138003Wye, 3-phaseWinding no. 6062Temp rise 125/105/80 °C; ADS-521; feature code B448; max surge kVA 91
127/2203Wye12/6Winding 311/312
133/2303Wye12/6Winding 311/312
139/2403Wye12/6Winding 311/312
190-480WyeTemp rise 125/105 degrees C; Duty S/P; Max surge 2944 kVA; Winding No. 311; ADS-309; Feature code B731-2
190/3803WyeWinding 311; ADS-631; feature code BC37-2
200/4003WyeWinding 311; ADS-310; feature code BC35-2
208/416WyeTemp rise 105/80 degrees C; Duty S/P; Max surge 2944 kVA; Winding No. 311; ADS-309; Feature code B733-2
208/4163WyeWinding 311; ADS-632; feature code BC44-2
220/380WyeTemp rise 105/80 degrees C; Duty S/P; Max surge 3313 kVA; Winding No. 311; ADS-310; Feature code B599-2
220/38036 leads6Winding no. 13; 125°C rise rating 2004 kW / 2505 kVA; stator resistance L-L 0.00102 Ohms; rotor resistance 2.31 Ohms @22°C
240/41636 leads6Winding no. 13; 125°C rise rating 2004 kW / 2505 kVA; stator resistance L-L 0.00102 Ohms; rotor resistance 2.31 Ohms @22°C
240/4163Wye12/6Winding 311/312
254/44036 leads6Winding no. 312; 125°C rise rating 2000 kW / 2500 kVA; stator resistance L-L 0.00152 Ohms; rotor resistance 2.31 Ohms @22°C
254/4403Wye12/6Winding 311/312
266/4603Wye12/6Winding 311/312
277/48036 leads6Winding no. 312; 125°C rise rating 2080 kW / 2600 kVA; stator resistance L-L 0.00152 Ohms; rotor resistance 2.31 Ohms @22°C
277/4803Wye4 WireVoltage-277/480, 3 Phase, Wye, 4 Wire
277/4803Wye, 4 WireFeature code R002-2 Voltage-277/480, 3 Phase, Wye, 4 Wire
280/4163WyeWinding 311; ADS-632; feature code B733-2
346/60036 leads6Winding no. 07; 125°C rise rating 2080 kW / 2600 kVA; stator resistance L-L 0.00220 Ohms; rotor resistance 2.31 Ohms @22°C
347/6003Wye6Winding 07; ADS-309; feature code B720-2
380WyeTemp rise 80 degrees C; Duty S; Max surge 3866 kVA; Winding No. 312; ADS-311; Feature code B660-2
3803WyeWinding 311; ADS-632; feature code BC43-2
3803Wye, 3-phaseWinding no. 7327Temp rise 150/125/105 °C; ADS-335; feature code B595; max surge kVA 312
380-480WyeTemp rise 125/105 degrees C; Duty S/P; Max surge 2944 kVA; Winding No. 312; ADS-309; Feature code B282-2
4003WyeWinding 312; ADS-310; feature code BC36-2
41603Wye, 3-phaseWinding no. 6307Temp rise 125/105/80 °C; ADS-324; feature code B467; max surge kVA 51

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 oil capacity of the Cummins/Onan QSK23-G7 NR2?

The Cummins/Onan QSK23-G7 NR2 engine has an oil capacity of 102.0 liters.

What is the displacement of the Cummins/Onan QSK23-G7 NR2?

The Cummins/Onan QSK23-G7 NR2 has a displacement of 23.15 liters with 6 cylinders.

Which generators use the Cummins/Onan QSK23-G7 NR2 engine?

The Cummins/Onan QSK23-G7 NR2 powers 9 generator set(s), including Cummins/Onan 600 DQCA, Cummins/Onan 750 DQCB, Cummins/Onan 800 DQCC, Cummins/Onan 800DQCC-A034N301, Cummins/Onan DQCA.

What is a common problem with the Cummins/Onan QSK23-G7 NR2 engine?

A commonly reported issue on generators using the Cummins/Onan QSK23-G7 NR2 is: Over Current.