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Cummins 6B5.9 Engine

The Cummins 6B5.9 is a heavy-duty, 4-stroke, in-line 6-cylinder diesel engine. It is a foundational model within the widely respected Cummins B-series family, engineered for versatile applications across industrial, marine, automotive, and power generation sectors. The structural architecture features a cast-iron block with a deep-skirt design, eliminating the need for separate structural oil pan frames. Its design optimizes reliability by utilizing an integrated block configuration that minimizes external plumbing and gaskets, significantly reducing potential oil and coolant leak points. Aspiration on the base 6B model is naturally aspirated, though it shares the same robust overhead valve design, forged steel crankshaft, and high-strength connecting rods as its turbocharged counterparts. This ensures extreme durability, a long time between overhauls, and straightforward field maintenance.

The fuel architecture relies on a direct-injection design utilizing a high-precision mechanical inline injection pump (Bosch A-series or Stanadyne rotary pump) driven by the engine gear train. Engine speed regulation is maintained by a mechanical governor capable of close speed control for industrial applications. The low-pressure delivery circuit features a mechanical lift pump, while primary filtration is managed through a single spin-on fuel filter and water separator assembly designed to capture particulate matter and moisture before entering the high-pressure fuel lines.

The lubrication circuit is a full-pressure system driven by a high-capacity, gear-type oil pump mounted directly to the engine block. The system utilizes a single, high-efficiency spin-on full-flow combination filter canister. An integrated plate-type oil cooler is built into the engine block side jacket to regulate oil temperature during high-load operations.

Thermal regulation is managed by a liquid cooling circuit utilizing a high-output, belt-driven centrifugal water pump to circulate coolant through the engine block and cylinder head. System temperature is controlled by a pellet-type thermostat configured to start opening at 82C and achieve a fully open state at 95C. The maximum allowable operating coolant temperature under peak load conditions is limited to 100C to prevent thermal distortion of the cylinder head.

General Technical Data

Engine Specifications

Engine Model ............... Cummins 6B5.9
Engine Type ............... 4-cycle inline 6-cylinder direct injection 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) ............... 80-135 (60-100)
Rated Engine Speed, rpm ............... 2200-2500
Peak Torque ............... 420-650 Nm (310-479 lb-ft) at 1300-1600 rpm
Idle Speed ............... 700-800 rpm
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 16.5:1-17.5:1
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 ............... 45-90

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) ............... 37.4-45.3 (950-1050)
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 ............... 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 or higher
Engine Oil Capacity, qts (L) .................. 13.6-16.8 (13.0-16.0)
Coolant Capacity, qts (L) ............... 15.7-21.0 (15.0-20.0)

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 6BT5.9-G1 Specs
  
• Cummins 6BT5.9-G2 Specs
  
• Cummins 6BTA5.9 Specs
  
• Cummins 6BTAA5.9-G12 Specs
  

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