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Cummins 6T-590 Engine

The Cummins 6T590 (Case/Cummins 6-5.9 or 6BT5.9) is a 5.9-liter, inline 6-cylinder, four-stroke, turbocharged diesel engine. It is widely recognized for its heavy-duty reliability, long operational life, and simple structural layout. Built with a cast-iron engine block and a deep-skirt, parent-bore cylinder design without wet liners, it delivers high torsional rigidity and simplified block machining. Key features include a robust gear-driven camshaft train, a forged steel crankshaft supported by seven main bearings, and a single-piece cast-iron cylinder head. The engine is predominantly used in mid-sized industrial equipment, agricultural machinery (such as Case IH tractors), and commercial power units.

The valvetrain features an Overhead Valve (OHV) layout utilizing a single, gear-driven camshaft located within the cylinder block. The engine incorporates a standard 2 valves per cylinder setup (6 intake valves, 6 exhaust valves) operated via mechanical lifters, solid pushrods, and rocker arm assemblies. The cylinder block geometry consists of a fixed displacement architecture totaling 5.9 liters (359 cubic inches). Cylinder Bore: 102.0 mm (4.02 in). Piston Stroke: 120.0 mm (4.72 in).

Fuel delivery relies entirely on a mechanical direct-injection system. The configuration uses a timing-gear-driven, frame-mounted mechanical injection pump (typically a Bosch rotary or inline layout) governed mechanically via a flyweight assembly. Low-pressure fuel is supplied via a mechanical lift pump through a primary dual-stage fuel filter and water separator array. High-pressure lines distribute metered fuel directly to mechanical, multi-hole injection nozzles mounted vertically into the cylinder head, spraying directly into the piston combustion bowls.

The lubrication circuit utilizes a positive-displacement, gear-type oil pump driven directly by the crankshaft gear train. Lubricant is drawn through a pick-up tube from a stamped steel or cast oil pan equipped with a rear, front, or center sump configuration depending on application clearance. The pressurized oil passes through an integral liquid-to-liquid plate-type oil cooler element built into the side of the engine block before arriving at a spin-on full-flow filtration housing.

Thermal regulation is managed by a liquid-cooled, closed-loop configuration driven by an integrated belt-driven water pump. A single modulating thermostat controls flow bypass directly to the radiator circuit. The standard operating temperature range is restricted between 82C and 95C (180F to 203F) to ensure optimal combustion efficiency and minimize structural stress across the cylinder head.

General Technical Data

Engine Specifications

Engine Model ............... Cummins 6T-590
Engine Type ............... 4-cycle inline 6-cylinder direct injection turbocharged liquid-cooled diesel
Number of Cylinders ............... 6
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 4.02 (102.0)
Engine Stroke, in (mm) ............... 4.72 (120.0)
Displacement, cu.in (L) ............... 359 (5.9)
Rated Engine Power, hp (kW) ............... 115-160 (85-118)
Rated Engine Speed, rpm ............... 2100-2300
Peak Torque ............... 400 lb-ft (542 Nm) at 1600 rpm
Idle Speed ............... 700-800 rpm
Aspiration Type ............... Turbocharged
Compression Ratio ............... 17.5:1
Firing Order ............... 1-5-3-6-2-4
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure
Oil Pump Type ............... Gear-driven
Oil Filter Type ............... Full-flow, spin-on
Cooling System ............... Liquid-cooled
Water Pump Type ............... Belt-driven, centrifugal
Air Cleaner Type ............... Dry dual-stage
Starting System ............... Electric Starter
Electrical System ............... 12V or 24V
Alternator Rating, Amps ............... 35-70

Fuel System

Fuel System ............... Direct injection
Injection Pump Type ............... Rotary or inline
Fuel System Control ............... Mechanical
Governor Type ............... Mechanical
Fuel Injector Type ............... Multi-hole
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 43.3-47.2 (1100-1200)
Overall Width, in (mm) ............... 27.6-31.5 (700-800)
Overall Height, in (mm) ............... 43.3-47.2 (1100-1200)
Dry Weight, lbs (kg) ............... 880-1055 (400-480)

Maintenance Data

Service Information

Thermostat begins opening ............... 82C (180F)
Thermostat fully open ............... 95C (203F)
Cooling system pressure ............... 70-100 kPa (10-15 psi)
Operating oil pressure ............... 300-450 kPa (44-65 psi)
Idle oil pressure ............... 100-150 kPa (15-22 psi)
Intake Valve Clearance, in (mm) ............... 0.254 (0.010)
Exhaust Valve Clearance, in (mm) ............... 0.508 (0.020)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CF-4, CG-4, CI-4, or CJ-4
Engine Oil Capacity, qts (L) .................. 13.6-16.8 (13.0-16.0)
Coolant Capacity, qts (L) ............... 21.0-26.3 (20.0-25.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 500 hours
Inspect air filter ............... Every 100 hours
Replace air filter ............... Every 300 hours
Change coolant ............... Every 2000 hours
Valve-lash adjustment ............... Every 1000 hours
Injector inspection ............... Every 1500-2000 hours
Compression test ............... Every 2500 hours
Drain water separator ............... As required
Belt inspection ............... As required

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 4.0165-4.0177 (102.000-102.030)
Crankshaft Journal Outside Diameter, in (mm) ............... 3.2672-3.2682 (82.987-83.013)
Crank Pin Outside Diameter, in (mm) ............... 2.7160-2.7170 (68.987-69.013)
Crankshaft End Play, in (mm) ............... 0.0040-0.0130 (0.102-0.330)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.3129-0.3139 (7.947-7.973)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.3121-0.3131 (7.927-7.953)
Intake Valve Guide Inside Diameter, in (mm) ............... 0.3154-0.3169 (8.011-8.049)
Exhaust Valve Guide Inside Diameter, in (mm) ............... 0.3154-0.3169 (8.011-8.049)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0040 (0.038-0.102)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0023-0.0048 (0.058-0.122)
Intake Valve Spring Free Length, in (mm) ............... 1.879 (47.73)
Exhaust Valve Spring Free Length, in (mm) ............... 1.879 (47.73)
Intake Cam Height, in (mm) ............... 1.8482-1.8612 (46.945-47.275)
Exhaust Cam Height, in (mm) ............... 1.8385-1.8540 (46.697-47.091)
Piston Pin Outside Diameter, in (mm) ............... 1.5746-1.5750 (39.995-40.005)
Piston Pin to Piston Bore Clearance, in (mm) ............... 0.0003-0.0007 (0.008-0.018)
Second Ring Side Clearance, in (mm) ............... 0.0027-0.0045 (0.068-0.115)
Oil Ring Side Clearance, in (mm) ............... 0.0015-0.0033 (0.038-0.085)
Top Ring End Gap, in (mm) ............... 0.0100-0.0220 (0.254-0.559)
Second Ring End Gap, in (mm) ............... 0.0100-0.0220 (0.254-0.559)
Oil Ring End Gap, in (mm) ............... 0.0100-0.0220 (0.254-0.559)

Tightening Torque Specs

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 ............... 105-135 Nm (77-100 lb-ft)
Rocker Arm Shaft Bolts ............... 25 Nm (18 lb-ft)
Crankshaft Pulley Bolts ............... 210 Nm (155 lb-ft)
Oil Drain Plug ............... 40-50 Nm (30-37 lb-ft)

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• Cummins 6T-830 Specs
  

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