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Caterpillar 3056T Engine

The Caterpillar 3056T is a heavy-duty, 4-stroke, inline 6-cylinder diesel engine engineered for reliable performance in demanding industrial, marine, and power generation applications. Combining a compact footprint with high power density, this engine utilizes a turbocharged aspiration system to improve thermal efficiency and optimize combustion. Known for its robust structural integrity, the engine features a rigid cylinder block design, highly durable internal components, and direct injection for responsive power delivery across its operating range.

This engine features a direct injection fuel system utilizing an advanced rotary distribution or electronic injection pump setup depending on the exact build variant. A low-pressure mechanical fuel lift pump transfers fuel from the source tank, routing it through a primary fuel filter/water separator element to remove contaminants. The fuel is then fed to the secondary fuel filter and into the injection pump, which serializes high-pressure distribution to individual mechanical or electronic unit injectors. Excess fuel used for injector cooling and pump lubrication is returned back to the main fuel tank through a dedicated return line circuit.

Engine lubrication is maintained by a full-pressure system driven by a gear-driven oil pump. High-pressure oil passes through an integral plate-type engine oil cooler and a dual-element, full-flow spin-on oil filter assembly before entering the main oil galleries. The total system refill capacity is 15 to 18 liters (3.9 to 4.8 gallons) depending on the oil pan configuration. The factory specifies the use of high-quality Caterpillar DEO 10W30 or 15W40 oils to maintain component longevity and handle structural stress.

The liquid-cooling configuration uses a gear-driven centrifugal jacket water pump to force coolant through the internal engine blocks and cylinder head passages. Temperature regulation is controlled by an integrated thermostat and housing assembly. Depending on whether the application uses an industrial radiator, a heat exchanger with a cupro-nickel tube bundle, or a keel-cooled circuit, the total cooling system fluid capacity is 24 to 25.3 liters (6.3 to 6.7 gallons).

General Technical Data

Engine Specifications

Engine Model ............... Caterpillar 3056T
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) ............... 3.94 (100.0)
Engine Stroke, in (mm) ............... 5.00 (127.0)
Displacement, cu.in (L) ............... 365 (6.0)
Rated Engine Power (Industrial), hp (kW) ............... 114-129 (85-95)
Rated Engine Power (Generator), hp (kW) ............... 147-168 (110-120)
Rated Engine Power (Marine), hp (kW) ............... 185-205 (137-152)
Rated Engine Speed (Industrial), rpm ............... 2200-2400
Rated Engine Speed (Generator), rpm ............... 1500-1800
Rated Engine Speed (Marine), rpm ............... 2600
Peak Torque ............... 515-577 Nm (380-425 lb-ft) at 1400-1600 rpm
Idle speed ............... 700-800 rpm
Aspiration Type ............... Turbocharged
Compression Ratio ............... 15.5:1-17.0:1
Firing Order ............... 1-5-3-6-2-4
Crankshaft Type ............... Forged steel
Piston Type ............... Cast-aluminum alloy
Con Rod Type ............... Forged steel
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure wet-sump
Oil Pump Type ............... Gear-driven
Cooling System ............... Liquid-cooled
Water Pump Type ............... Gear-driven, centrifugal
Air Cleaner Type ............... Dry element
Starting System ............... Electric Starter
Electrical System ............... 12V or 24V
Alternator Rating, Amps ............... 65-85

Fuel System

Fuel System ............... Direct injection
Injection Pump Type ............... Mechanical
Fuel Injector Type ............... Multi-hole pencil-type
Governor Type ............... Mechanical
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 42 (1070)
Overall Width, in (mm) ............... 30.6 (775)
Overall Height, in (mm) ............... 31.5 (800)
Dry Weight (Industrial), lbs (kg) ............... 1310 (595)
Dry Weight (Marine), lbs (kg) ............... 1345 (610)

Maintenance Data

Service Information

Thermostat begins opening ............... 82C (180F)
Thermostat fully open ............... 95C (203F)
Cooling system pressure ............... 70-90 kPa (10-13 psi)
Operating oil pressure ............... 300-420 kPa (44-61 psi)
Intake Valve Clearance, in (mm) ............... 0.008 (0.20)
Exhaust Valve Clearance, in (mm) ............... 0.018 (0.45)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CH-4/SJ or higher
Engine Oil Capacity, qts (L) .................. 15.7 (15.0)
Coolant Capacity, qts (L) ............... 26.3 (25.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 500 hours
Inspect air filter ............... Every 50 hours
Change coolant ............... Every 2 years
Valve-lash adjustment ............... Every 1000 hours
Injector inspection ............... Every 1000-1500 hours
Compression test ............... Every 2000 hours
Drain water separator ............... As required
Belt inspection ............... Every service cycle

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ................ 3.9370-3.9382 (100.000-100.030)
Crankshaft Journal Outside Diameter, in (mm) ................ 2.9984-2.9992 (76.159-76.180)
Crank Pin Outside Diameter, in (mm) ................ 2.4992-2.5000 (63.479-63.500)
Crankshaft End Play, in (mm) ................ 0.0020-0.0150 (0.050-0.380)
Intake Valve Stem Outside Diameter, in (mm) ................ 0.3528-0.3537 (8.961-8.984)
Exhaust Valve Stem Outside Diameter, in (mm) ................ 0.3516-0.3525 (8.931-8.954)
Intake Valve Guide Inside Diameter (Installed), in (mm) ................ 0.3543-0.3553 (9.000-9.025)
Exhaust Valve Guide Inside Diameter (Installed), in (mm) ................ 0.3543-0.3553 (9.000-9.025)
Intake Valve Stem to Guide Clearance, in (mm) ................ 0.0006-0.0025 (0.016-0.064)
Exhaust Valve Stem to Guide Clearance, in (mm) ................ 0.0018-0.0037 (0.046-0.094)
Intake Valve Spring Free Length, in (mm) ................ 1.9189 (48.740)
Exhaust Valve Spring Free Length, in (mm) ................ 1.9189 (48.740)
Intake Cam Height, in (mm) ................ 1.1850-1.1913 (30.100-30.260)
Exhaust Cam Height, in (mm) ................ 1.1823-1.1886 (30.030-30.190)
Piston Pin Outside Diameter, in (mm) ................ 1.3748-1.3750 (34.920-34.925)
Piston Pin to Piston Bore Clearance, in (mm) ................ 0.0004-0.0012 (0.010-0.030)
Second Ring Side Clearance, in (mm) ................ 0.0028-0.0043 (0.070-0.110)
Oil Ring Side Clearance, in (mm) ................ 0.0020-0.0035 (0.050-0.090)
Top Ring End Gap, in (mm) ................ 0.0110-0.0220 (0.280-0.560)
Second Ring End Gap, in (mm) ................ 0.0110-0.0220 (0.280-0.560)
Oil Ring End Gap, in (mm) ................ 0.0110-0.0220 (0.280-0.560)

Tightening Torque Specs

Cylinder Head Bolts (Stage 1) ............... 90 Nm (66 lb-ft)
Cylinder Head Bolts (Stage 2) ............... 130 Nm (96 lb-ft)
Main Bearing Cap Bolts ............... 140 Nm (103 lb-ft)
Connecting Rod Cap Bolts ............... 90 Nm (66 lb-ft)
Flywheel Housing-to-Block Bolts ............... 75 Nm (55 lb-ft)
Flywheel-to-Crankshaft Bolts ............... 115 Nm (85 lb-ft)
Injector Clamp Bolt ............... 35 Nm (26 lb-ft)
Oil Pan Bolts ............... 27 Nm (20 lb-ft)
Fuel Injection Pump Mounting Nuts ............... 24 Nm (18 lb-ft)

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• Caterpillar Engines Specs
  
• Cat C6.6 Specs
  
• Cat 3054T Specs
  
• Cat 3054 Specs
  
• Cat 3054C Specs
  
• Cat 3054E Specs
  
• Cat 3056 Specs
  
• Cat 3056E Specs
  

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