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Cummins/Onan QSB4.5 Engine

Name: Cummins/Onan QSB4.5 Engine
Brand: Cummins/Onan

The Cummins/Onan QSB4.5 is a 4.5 L 4-cylinder turbocharged and charge-air cooled engine rated at 1470 rpm, producing up to 78 kW. It powers generator sets from Cummins/Onan, including the CFP5E-F10, CFP5E-F20, CFP5E-F40 and CFP5EVS-F10. It holds 11.6 L (3.1 gal) of oil and 13 L (3.4 gal) of coolant.

Also known as: Cummins QSB4.5

4.5 L

Displacement

Cylinders

1470 rpm

Rated speed

78 kW

Gross power

On this pageSpecs Generator sets Maintenance FAQ Service intervals Torque & specs Fluids Procedures

Engine specifications

Oil capacity	11.6 L
Coolant capacity	13.0 L
Displacement	4.5 L
Cylinders	4
Aspiration	Turbocharged and Charge-Air Cooled
Rated speed	1470 rpm
Gross power	78 kW

Generator sets powered by this engine

Cummins/Onan CFP5E-F10Cummins/Onan CFP5E-F20Cummins/Onan CFP5E-F40Cummins/Onan CFP5EVS-F10Cummins/Onan CFP5EVS-F20Cummins/Onan CFP5EVS-F40Cummins/Onan qsB4.5

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

Maintenance schedule

Item	Spec	Capacity	Part #
Fuel filter	Recommended fuel filter - primary Cummins Filtration FF5612 (Cummins 4989106); secondary element AF26125		—
Oil filter	Recommended lube oil filter - Cummins Filtration LF3970		LF3970	Amazon $36.06 eBay $177.58 FridayParts $62.99
Battery	Battery cable size - minimum of 2/0 AWG and maximum cable length not to exceed 6 ft. (1.5 m)		—
Belt	Exhaust protection - Metal guards on manifolds and turbocharger; Exhaust flex connection - Steel, flanged; Stainless steel flex, NPT		—
Coolant	Cooling system - Tube and shell type, 60 PSI with NPTF connections; recommended minimum water supply pipe size to heat exchanger .75 in. (19.05 mm); recommended minimum water discharge pipe size from heat exchanger 1.00 in. (25.40 mm)		—
Oil	Oil capacity of pan (high - low) 11.6-9.5 qt. (11-9 L)	11.0 qt,L	—
Spark plug	Engine only - cold cranking amperes: 1300 CCA; Engine only - reserve capacity: 430 minutes		—

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

Service intervals

Item	Action	Hours	Months	Notes
Lubricating oil	Test	250 hr	6 mo	First 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.
filters	Change	1000 hr		with CENTINEL, depending on load factors
ELIMINATOR self cleaning filter core	Other	1500 hr		Requires servicing only every 1,500 hours. Saves up to 90% of lube system maintenance costs and increases productivity.
fuel filter	Change	1500 hr		Fleetguard NanoNet media
engine oil	Change	4500 hr		with CENTINEL, railway applications

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

Type	Item	Value	Unit	Condition
Other	Pressure sensing line nominal size inside diameter	1/2	in. (12.7 mm)	connected between the transducer (located under the FPDP) and the pump discharge flange and the discharge check valve
Pressure	Cooling loop cooling water pressure limit	270	psi	installations where the discharge pressure is greater than 270 psi (pressure reducing valve required upstream of the cooling loop)
Pressure	Discharge set point pressure / maximum control pressure	100/110, 170/175, or 240/250	psi	set by the factory and not adjustable; specify at time of order
Pressure	VSPLC set point range	100 to 400	psi

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	Notes
Engine oil		Cummins Engine Oil Recommendations Bulletin 3810340	Used to analyze oil samples for high horsepower engines with Eliminator™ oil filter option.
Fuel	B100 biodiesel	ASTM D6751	Must conform prior to blending; revised to include a cold soak test; stability requirement still in effect.
Fuel	B20 biodiesel blend	ASTM D7467	Applies 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.
Fuel	B5 biodiesel		All Cummins automotive and industrial engines are compatible with B5 biodiesel.
Fuel	biodiesel (Europe)	EN 14214	Published 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

Oil sampling for high horsepower engines with Eliminator™ oil filter option maintenance

Take oil samples every 250 hours of operation.
Analyze samples according to Cummins Engine Oil Recommendations Bulletin 3810340.
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.

Install new fuel filters when switching to B20.
Replace fuel filters at half the standard interval for the next two fuel filter changes.
After the initial period, revert to intervals specified in the O & M manual.
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.

Aftermarket parts that fit this engine

0327-1507 FridayParts $499.99 FP-XP-0041835

Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.

Common questions

What is the oil capacity of the Cummins/Onan QSB4.5?

The Cummins/Onan QSB4.5 engine has an oil capacity of 11.6 liters.

What is the displacement of the Cummins/Onan QSB4.5?

The Cummins/Onan QSB4.5 has a displacement of 4.5 liters with 4 cylinders.

Which generators use the Cummins/Onan QSB4.5 engine?

The Cummins/Onan QSB4.5 powers 7 generator set(s), including Cummins/Onan CFP5E-F10, Cummins/Onan CFP5E-F20, Cummins/Onan CFP5E-F40, Cummins/Onan CFP5EVS-F10, Cummins/Onan CFP5EVS-F20.