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Cummins/Onan QSK38-G2 Engine

The Cummins/Onan QSK38-G2 is a 38 L 12-cylinder turbocharged, after-cooled engine rated at 1500 rpm. It powers generator sets from Cummins/Onan, including the QSK38.

Also known as: Cummins QSK38-G2

Part of the Cummins/Onan QSK38 engine family — 7 variants share parts & fitment.

38.0 L
Displacement
12
Cylinders
1500 rpm
Rated speed

Engine specifications

Displacement38.0 L
Cylinders12
Aspirationturbocharged, After-cooled
Rated speed1500 rpm

Service intervals

7
ItemActionHoursMonthsNotes
Lubricating oilTest250 hr6 moFirst service — For high horsepower engines with Eliminator™ oil filter option: take oil samples every 250 hours and analyze per Cummins Engine Oil Recommendations Bulletin 3810340; repeat for at least three oil change intervals.
filtersChange1000 hrwith CENTINEL, depending on load factors
ELIMINATOR self cleaning filter coreOther1500 hrRequires servicing only every 1,500 hours. Saves up to 90% of lube system maintenance costs and increases productivity.
fuel filterChange1500 hrFleetguard NanoNet media
valve clearanceCheck2000 hrB-Series (4BT3.3): valve clearance checks not required for 2000 hours, twice the industry standard
engine oilChange4500 hrwith CENTINEL, railway applications
engine overhaulOther20000 hrQSK23-Series: expected life cycle to 20,000 hours before first overhaul

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
Engine oilCummins Engine Oil Recommendations Bulletin 3810340Used to analyze oil samples for high horsepower engines with Eliminator™ oil filter option.
FuelB100 biodieselASTM D6751Must conform prior to blending; revised to include a cold soak test; stability requirement still in effect.
FuelB20 biodiesel blendASTM D7467Applies to biodiesel blends B6–B20; includes oxidation stability requirement; replaces Cummins' previous EMA B20 specification requirement. Must be purchased from a BQ9000 Certified Marketer; B100 must be sourced from a BQ9000 Accredited Producer.
FuelB5 biodieselAll Cummins automotive and industrial engines are compatible with B5 biodiesel.
Fuelbiodiesel (Europe)EN 14214Published by CEN, European Committee for Standardization. Equivalent biodiesel specifications required internationally.

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

Procedures

2
Oil sampling for high horsepower engines with Eliminator™ oil filter option maintenance
  1. Take oil samples every 250 hours of operation.
  2. Analyze samples according to Cummins Engine Oil Recommendations Bulletin 3810340.
  3. Repeat for at least three oil change intervals to ensure consistent oil behavior.
Switching from petrodiesel to B20 on used engines maintenance

⚠ B20 has a solvent nature and may clean the vehicle fuel tank and lines.

  1. Install new fuel filters when switching to B20.
  2. Replace fuel filters at half the standard interval for the next two fuel filter changes.
  3. After the initial period, revert to intervals specified in the O & M manual.
  4. For EPA 2007 on-highway midrange engines, sample oil for the first 6 months to monitor fuel dilution.

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

Parts cataloged across the Cummins/Onan QSK38 family

4
Part #DescriptionCategory
MCBQSK0068Water Pump Gasket SetGasket
M-2885786Cylinder Liner KitService part / kit
M-3007525Cylinder Liner KitService part / kit
M-3022157Cylinder LinerService part / kit

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Common questions

What is the displacement of the Cummins/Onan QSK38-G2?

The Cummins/Onan QSK38-G2 has a displacement of 38.0 liters with 12 cylinders.

Which generators use the Cummins/Onan QSK38-G2 engine?

The Cummins/Onan QSK38-G2 powers 1 generator set(s), including Cummins/Onan QSK38.