Cummins 6T-590 Specifications
| Engine Model: Cummins 6T-590 |
| Engine Type: 4-stroke in-line 6-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 359 cu.in (5.9 L) |
| Rated Engine Power: 115-160 Hp (85-118 kW) at 2000 rpm |
| Fuel System Type: Direct injection |
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The Cummins 6T-590 is a 5.9-liter, in-line
6-cylinder, turbocharged diesel engine, part of the renowned Cummins B
Series family. This engine was widely utilized in industrial
applications, construction machinery (such as Case equipment), and
agricultural vehicles from the mid-1980s through the 1990s. It is
distinguished by its mechanical fuel system and robust construction,
offering a reputation for durability and ease of service.
The 6T-590 designation indicates the naturally aspirated or turbocharged
configuration within the 5.9L platform, delivering reliable power
characterized by strong low-end torque, making it suitable for
heavy-duty equipment where consistent performance under load is
required.
The Cummins 6T-590 operates on a four-stroke cycle with an in-line
6-cylinder configuration utilizing forced induction via a turbocharger.
Total displacement is 5.9 liters (359 cubic inches), derived from a bore
of 102 mm (4.02 in) and a stroke of 120 mm (4.72 in). The compression
ratio for these mechanical 12-valve versions is 17.5:1. The firing order
is 1-5-3-6-2-4.
Standard output power ratings vary depending on the specific
application, generally ranging from 115 HP to 160 HP (85-118 kW). A
common rating for industrial configurations is 129 HP (95 kW) at 2000
RPM. Peak torque is 400 lb-ft (542 Nm) at 1600 RPM for standard
industrial or truck configurations. Engine rotation is counterclockwise
when viewed from the flywheel end.
The cylinder block is constructed from cast iron, providing a rigid
foundation for the internal components. It features parent-bore cylinder
liners, meaning the pistons run directly within the machined bores of
the block without removable wet or dry sleeves.
The block design incorporates a deep skirt for structural strength and
stability. It is configured to support the in-line 6-cylinder
arrangement with seven main bearings to ensure crankshaft rigidity under
heavy loads. The block integrates the oil galleries for the lubrication
system and water passages for the cooling jacket.
The cylinder head is a cast iron cross-flow design, optimized for the
turbocharged engine’s airflow requirements. It utilizes a 12-valve
configuration (2 valves per cylinder), actuated by a mechanical
valvetrain. The valve train consists of a camshaft located in the
cylinder block, pushrods, and rocker arms.
The cylinder head gasket is designed to withstand high cylinder
pressures. Remanufactured cylinder heads for the 6T-590 are commonly
available with new valve guides and seats installed, with casting
numbers such as 399273-05 and OEM number J920612 being referenced for
replacement parts. The cylinder head is secured using multi-step
torque-to-yield bolts.
The engine utilizes a mechanical direct injection fuel system. Fuel
delivery is managed by either a rotary or inline injection pump, which
is gear-driven from the engine camshaft. This system relies on a
mechanical flyweight governor to regulate fuel delivery and engine speed
based on load conditions.
The injection pump supplies high-pressure fuel to the unit injectors or
individual injectors, depending on the specific variant. The system is
entirely mechanical, requiring no electronic control unit (ECU) for
basic operation, which simplifies troubleshooting and field repairs.
The lubrication system is a pressure-feed type, utilizing a rotary
gear-type oil pump mounted inside the engine. The system capacity ranges
from 14.2 to 15.1 liters (15-16 U.S. quarts). Oil pressure at rated
speed is maintained between 40 and 60 PSI (276 - 414 kPa).
The engine is equipped with a full-flow oil filter and may include an
oil cooler to maintain optimal operating temperatures. For applications
utilizing an oil cooler, components are often cross-compatible with the
broader 5.9L engine family, including the 6BT5.9 and 6BTA5.9 models.
The cooling system is liquid-cooled, utilizing a water pump to circulate
coolant through the cylinder block and cylinder head. The total coolant
capacity for the engine alone is 24.6 liters. System regulation is
controlled by a thermostat, with a maximum recommended water temperature
of 100°C (212°F). Heat rejection is managed through a radiator, and in
many equipment installations, a viscous fan drive is used to control
cooling airflow based on engine temperature.
The electrical system is configured as either 12-volt or 24-volt
negative ground (negative earth) depending on the original equipment
manufacturer (OEM) specifications. The starting system includes a
high-torque starter motor. The engine is equipped with a turbocharger,
frequently the Holset H1C model, which is integral to achieving the
rated power output.
The intake system routes compressed air through an aftercooler or
charge-air cooler in some configurations to increase air density before
entry into the cylinders. The exhaust system includes a cast-iron
manifold designed to withstand thermal cycling.
The dry weight of a long block (engine without manifolds, turbo, or
accessories) is 375 kg (827 lbs). A fully dressed unit, complete with
turbocharger, fuel system, alternator, starter, and flywheel, ranges
from 426 kg to 500 kg (940 lbs to 1100 lbs). The approximate dimensions
of the engine are 120 cm length, 80 cm width, and 120 cm height, though
these dimensions may vary slightly based on the installed accessories
and specific equipment housing.
Regular maintenance intervals are critical for longevity. The engine oil
and filter should be changed every 250 to 300 hours of operation under
normal conditions. The fuel filter element requires replacement at
similar intervals or more frequently if fuel contamination is suspected.
The cooling system should be flushed and the coolant replaced every
2,000 hours or 2 years.
Valve lash (clearance) adjustments are necessary as part of routine
maintenance, typically performed every 1,000 to 1,500 hours, with
specific intake and exhaust valve clearance specifications determined by
the service manual for the exact engine CPL (Control Parts List). The
air filter element must be inspected regularly and replaced when the
restriction indicator signals a need.
Cylinder Head Bolts: 90 Nm (66 lb-ft).
Main Bearing Caps: 176 Nm (129 lb-ft).
Connecting Rod Bolts: 100 Nm (73 lb-ft).
Flywheel Bolts: 105 to 135 Nm (77 to 100 lb-ft).
Rocker Arm Shaft Bolts: 25 Nm (18 lb-ft).
The Cummins 6T-590 engine was extensively used in off-highway equipment
and industrial machinery. It is commonly found in Case construction
equipment, including backhoe loaders and agricultural tractors, where it
served as a power unit. Other applications include industrial
generators, compressors, and agricultural combines.
The engine’s robust design and mechanical fuel system made it a
preferred choice for equipment requiring high reliability in dusty or
remote environments. Its compatibility with the broader 6BT5.9 platform
ensures that many components are interchangeable across various
industrial brands.
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