Cummins L375-30 Specifications
| Engine Model: Cummins L375-30 |
| Engine Type: 4-stroke in-line 6-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 543 cu.in (8.9 L) |
| Rated Engine Power: 375 Hp (276 kW) at 2200 rpm |
| Fuel System Type: Mechanical inline injection pump |
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The Cummins L375-30 is a heavy-duty, in-line
6-cylinder diesel engine renowned for its durability, fuel efficiency,
and reliable power delivery. Part of the reputable Cummins L-series,
this 8.9-liter powerplant is designed to meet the rigorous demands of
mid-range commercial vehicles, construction equipment, and agricultural
machinery. It utilizes a robust mechanical fuel system, making it a
preferred choice for applications where simplicity and ease of
serviceability are paramount.
The engine’s combination of turbocharging and air-to-air charge cooling
ensures efficient combustion, delivering a broad torque curve with a
rated power of 276 kW (375 hp). Its architecture emphasizes structural
integrity, using a deep-skirt cylinder block and a high-strength
cylinder head to withstand high cylinder pressures over extended service
intervals. The L375-30 represents a balance of proven mechanical
technology and performance, built to operate consistently under variable
load conditions.
Engine Type: 4-cycle, In-line, 6-cylinder diesel.
Aspiration: Turbocharged and Air-to-Air Intercooled.
Displacement: 8.9 L (543 cu.in).
Bore and Stroke: 114 mm x 145 mm (4.49 in x 5.71 in).
Compression Ratio: 16.6:1.
Valvetrain: 24-valve cylinder head (4 valves per cylinder).
Rated Power: 276 kW (375 hp) at 2200 RPM.
Peak Torque: 1480 Nm (1092 lb-ft) at 1400 RPM.
Governed Speed (Max No-Load): 2500 RPM.
Idle Speed: 700 ± 100 RPM.
Specific Fuel Consumption: 228 g/kWh at rated power.
Fuel System: Mechanical Bosch P7100 inline injection pump with an RVQ-K
governor.
Emissions Certification: Euro III (some variants may meet Euro II).
Lubrication System: Full pressure circulation.
Cooling System: Liquid-cooled, centrifugal water pump.
Electrical System: 24-volt starting motor and alternator.
Cold Start Capability: Lowest starting temperature is -10°C (14°F).
Weight (Net/Dry): 650 kg to 680 kg (1433-1500 lb).
Packing Weight (Gross): 700 kg to 720 kg (1543-1587 lb).
The cylinder block is constructed from high-grade cast iron, providing a
rigid foundation for all major rotating and reciprocating components.
The design incorporates a deep-skirt configuration, where the cylinder
walls extend below the crankshaft centerline, enhancing structural
stiffness and minimizing noise, vibration, and harshness. The block
features parent bore cylinder bores, machined to exact tolerances
without the use of liners in the standard configuration, ensuring
long-term durability under high cylinder pressures.
Oil galleries are integrally cast to supply pressurized lubricant to the
crankshaft, camshaft, and piston cooling jets. The block also includes
mounting provisions for auxiliary components such as the air compressor,
power steering pump, and the Bosch P7100 injection pump. A rear gear
train housing is integrated into the block design, allowing for direct
mounting of the fuel pump and accessory drives.
The cylinder head is a single-piece, high-strength cast iron component
designed to accommodate a cross-flow induction system. It incorporates a
24-valve configuration, with four valves per cylinder - two intake and
two exhaust - optimizing volumetric efficiency and allowing for a
centrally located fuel injector. The valve train operates via a overhead
camshaft arrangement driven by the rear gear train.
Valves are actuated by precision-machined camshaft lobes acting on
hardened steel rocker arms with adjustable screw-type lash setters.
Intake valves are larger in diameter to maximize air induction from the
turbocharger and charge air cooler, while exhaust valves are constructed
from a high-temperature alloy to withstand the elevated thermal loads of
combustion.
Replaceable valve guides and seats are installed to facilitate
serviceability. The cylinder head is secured to the block using
high-strength, torque-to-yield fasteners arranged in a specific sequence
to ensure a uniform clamping load across the sealing surface, which is
critical for maintaining the integrity of the multi-layer steel (MLS)
head gasket.
The fuel system is centered on a mechanical Bosch P7100 inline injection
pump, a unit known for its robustness and precise fuel metering in
high-load applications. This pump is flange-mounted to the rear gear
train and is gear-driven, ensuring precise timing relative to crankshaft
position. It is equipped with an RVQ-K mechanical governor, which
provides accurate speed control, droop adjustment, and integrated fuel
limiting functions for smoke control during acceleration.
The injection pump delivers fuel at high pressure through individual
high-pressure fuel lines to unit injectors, which are mechanically
actuated by the overhead camshaft. This system eliminates the need for
electronic control units on the engine, simplifying field diagnostics
and maintenance. A hand-primer pump is located on the fuel filter head
to assist in priming the system after filter changes.
A fuel transfer pump, mounted on the injection pump, draws fuel from the
tank, passes it through a spin-on fuel filter with water separation
capabilities, and supplies it to the injection pump. Excess fuel is
returned to the tank via a return line, providing a cooling function for
the injection system components.
The lubrication system operates on a full-pressure circulation
principle, utilizing a high-efficiency, positive-displacement gear-type
oil pump mounted inside the oil pan and driven by the crankshaft. Oil is
drawn from the sump through a strainer screen before being pressurized
by the pump. The pressurized oil is directed through a full-flow,
spin-on oil filter, which removes particulate contaminants before the
oil enters the main oil gallery.
From the main gallery, oil is distributed to the crankshaft main
bearings, connecting rod bearings, camshaft bearings, and the rear gear
train. Piston cooling is achieved through precisely aimed oil jets that
spray the underside of the piston crowns, reducing thermal stress and
extending component life.
Oil pressure is regulated by a spring-loaded bypass valve located on the
oil pump or filter head to maintain system pressure within operating
limits. A separate bypass valve ensures continued oil flow to critical
components in the event of a restricted filter. The oil pan is
constructed from stamped steel, with a capacity sized to support
extended drain intervals under normal operating conditions.
The cooling system is a pressurized, liquid-cooled design managed by a
centrifugal water pump mounted on the front of the engine block. Coolant
circulation begins when the water pump draws coolant from the radiator
bottom tank and forces it through the engine block and cylinder head
water jackets.
A thermostatically controlled bypass circuit allows the engine to reach
optimal operating temperature rapidly; the thermostat begins to open at
a predetermined temperature, directing coolant to the radiator for heat
dissipation. The system is designed to maintain maximum coolant
temperature at 100°C (212°F). The engine coolant capacity is 11.1 L
(11.7 qt).
A belt-driven fan provides forced airflow across the radiator core, with
fan drive options including direct-drive or viscous clutch types to
reduce parasitic power loss when cooling demand is low. System
pressurization, maintained by a radiator cap with a pressure relief
valve, raises the boiling point of the coolant to prevent localized
boiling and cavitation within the cylinder head water jackets.
| Intake and Exhaust Systems |
Air Intake System: Filtered air is drawn through a heavy-duty dry-type
air cleaner before entering the turbocharger compressor housing. The
compressed air from the turbocharger is directed through an air-to-air
charge air cooler, which reduces intake air temperature, increasing
density and allowing for more efficient combustion.
Exhaust System: The engine is equipped with a wastegated turbocharger
designed to control boost pressure at high engine speeds. The exhaust
manifold is a pulse-type design, isolating exhaust pulses to improve
turbine efficiency and transient response.
The 24-volt electrical system comprises a high-output alternator and a
robust starting motor. The alternator provides sufficient current to
support auxiliary electrical loads while maintaining battery charge.
Wiring harnesses are constructed with heavy-gauge insulation and sealed
connectors to resist environmental contaminants.
The overall length is 1149 mm (45.2 in), measured from the front
accessory drive to the rear face of the flywheel housing. Overall width
is 799 mm (31.5 in), measured at the widest point across the exhaust
manifold and injection pump. Overall height is 1022 mm (40.2 in),
measured from the lowest point of the oil pan to the highest point on
the cylinder head cover.
Net dry weight ranges from 650 kg to 680 kg (1433-1500 lb), varying
slightly based on installed accessories such as the alternator, starter,
and flywheel housing configuration. Gross packing weight, which includes
the engine mounted on a shipping skid with protective coverings, is
between 700 kg and 720 kg (1543-1587 lb).
Oil Change Interval: Standard interval is 250 hours or 15,000 km (9,300
miles) under normal operating conditions. Severe duty operation,
characterized by extended idling or high ambient temperatures,
necessitates a reduced interval.
Oil Type: High-quality diesel engine oil meeting API classification CI-4
or higher with a viscosity grade of 15W-40 is specified for most
operating environments. Oil System Capacity (with filter): 23.0 L (24.3
qt). Fuel Filter Replacement: Recommended every 500 hours or at every
other oil change.
Coolant Change Interval: Extended life coolant requires replacement
every 6 years or 600,000 km (375,000 miles). Valve Lash (Cold): Intake:
0.36 mm (0.014 in); Exhaust: 0.69 mm (0.027 in). Adjustment interval is
every 1000 hours. Air Filter Service: Inspect at regular intervals based
on restriction gauge reading; replace when restriction indicator shows a
high vacuum level.
Connecting Rod Cap Nuts: 80 Nm (59 lb-ft).
Main Bearing Cap Bolts: 130 Nm (96 lb-ft).
Cylinder Head Bolts (M16): 150 Nm (111 lb-ft).
Cylinder Head Bolts (M12): 100 Nm (74 lb-ft).
Flywheel Housing to Block: 70 Nm (52 lb-ft).
Flywheel to Crankshaft: 210 Nm (155 lb-ft).
Camshaft Gear Bolt: 200 Nm (148 lb-ft).
Injection Pump Drive Gear Nut: 220 Nm (162 lb-ft).
Rocker Arm Shaft Bolts: 110 Nm (81 lb-ft).
Valve Adjustment Lock Nuts: 25 Nm (18 lb-ft).
Oil Pan Bolts: 30 Nm (22 lb-ft).
Thermostat Housing Bolts: 25 Nm (18 lb-ft).
The Cummins L375-30 engine is utilized across a broad spectrum of medium
and heavy-duty applications where mechanical simplicity and high torque
output are required.
Medium/Heavy Trucks: Commonly installed in regional haul tractors, dump
trucks, concrete mixers, and refuse vehicles from manufacturers such as
Kenworth, Peterbilt, Freightliner, and International.
Buses: Used in intercity coaches, school buses, and transit buses
requiring a reliable power unit with predictable service intervals.
Construction Equipment: Serves as the prime mover for wheel loaders,
motor graders, excavators, and compactors.
Agricultural Machinery: Found in large tractors, self-propelled
sprayers, and combine harvesters where low-end torque and fuel economy
are critical.
Industrial Applications: Powers generator sets (prime and standby),
irrigation pumps, and drilling equipment.
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