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Cummins 6BTA5.9 Engine

The Cummins 6BTA5.9 is a highly reliable, heavy-duty inline 6-cylinder, 4-stroke diesel engine designed for marine, industrial, construction, and power generation applications. Utilizing a cast-iron, parent-bore block construction, this unit features a unitized design with roughly 40% fewer parts than conventional diesels, greatly increasing structural integrity and reducing failure points. The "BTA" designation identifies that the engine is turbocharged and aftercooled, using forced induction and an inlet air temperature mitigation system to ensure maximum thermal efficiency, low emissions, and consistent power delivery under heavy loads. The engine features a total displacement of 5.9 liters (359 cubic inches). The cylinder layout relies on a precise internal geometry with a standard bore of 102 mm (4.02 inches) and a stroke of 120 mm (4.72 inches).

Fuel distribution relies on a strictly mechanical injection architecture. The assembly incorporates a timing-driven mechanical high-pressure pump (Bosch P7100 inline injection pump or a Lucas/Cav rotary pump depending on application tier) equipped with a mechanical or optional electronic governor for precise speed control. Fuel is pressurized between 18 to 25 psi on the supply side before passing through a spin-on primary fuel filter with a water separator. High-pressure lines deliver fuel directly to closed-nozzle mechanical hole-type injectors that atomize fuel inside the bowl-in-piston combustion chamber. Excess fuel passes through an inline fuel cooler circuit prior to returning to the primary fuel tank.

Engine lubrication is driven by a high-capacity gear pump that routes oil through a full-flow, spin-on Cummins Fleetguard filter system and an integrated oil cooler to maintain proper viscosity. Normal operating oil pressure at rated engine speed remains stable between 44 to 65 psi, with a minimum allowable oil pressure of 10 psi at low idle. The engine uses a pressurized, water-cooled circuit governed by a mechanical thermostat to control engine temperature. Industrial configurations feature an engine-driven water pump driving fluid through an auxiliary radiator or an open fan loop. Auxiliary marine applications utilize a single-loop keel cooling setup or an engine-mounted heat exchanger combined with jacket-water aftercooling (JWAC) to drop intake air temperatures.

General Technical Data

Engine Specifications

Engine Model ............... Cummins 6BTA5.9
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) ............... 115-250 (85-185)
Rated Engine Speed, rpm ............... 1500-2500
Peak Torque ............... 450-700 Nm (332-516 lb-ft) at 1400-1600 rpm
Idle Speed ............... 700-800 rpm
Aspiration Type ............... Turbocharged and aftercooled
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 ............... 35-75

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) ............... 41.3-47.2 (1050-1200)
Overall Width, in (mm) ............... 27.6-31.5 (700-800)
Overall Height, in (mm) ............... 39.4-49.3 (1000-1150)
Dry Weight, lbs (kg) ............... 945-1100 (430-500)

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 ............... 70-100 kPa (10-15 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 or higher
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 300 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 ............... 160-180 Nm (118-133 lb-ft)
Main bearing caps ............... 150-170 Nm (111-125 lb-ft)
Connecting rod bolts ............... 70-85 Nm (52-63 lb-ft)
Flywheel bolts ............... 180-220 Nm (133-162 lb-ft)
Crankshaft pulley bolt ............... 200-240 Nm (148-177 lb-ft)
Glow plugs ............... 10-15 Nm (7-11 lb-ft)
Oil drain plug ............... 30-40 Nm (22-30 lb-ft)
Injector hold-down bolts ............... 20-25 Nm (15-18 lb-ft)

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• Cummins Engines Specs
  
• Cummins 6B5.9 Specs
  
• Cummins 6BT5.9-G1 Specs
  
• Cummins 6BT5.9-G2 Specs
  
• Cummins 6BTAA5.9-G12 Specs
  

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