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Caterpillar 3056E Engine

The Caterpillar 3056E is an in-line, 6-cylinder, 4-stroke industrial diesel engine heavily utilized in heavy machinery such as wheel loaders (Cat 928G), excavators (M322C), and forestry equipment. Representing an evolution from older mechanical models, the "E" designation marks the integration of advanced electronic engine management. It utilizes an Electronic Control Module (ECM) linked to a high-precision rotary fuel injection pump to meet Tier 2 and Tier 3 emission regulations while optimizing fuel economy and power curves. The engine features heavy-duty construction with a single cylinder head, dry cylinder liners, and automated piston cooling.

The fuel system is an electronically controlled, low-emissions direct injection system managed by the primary engine ECM. Fuel is pulled from the tank through a primary and secondary twin-filtration layout by an engine-driven fuel lift pump. It is then fed to an electronically controlled rotary distributor pump (typically a Bosch VP30 platform) containing its own dedicated pump ECM. The pump's internal fuel quantity and advance solenoid valves actuate precisely based on signals from the engine ECM, which monitors speed, timing, and manifold boost pressure sensors. High-pressure fuel lines deliver fuel to the individual non-serviceable mechanical fuel injectors fastened into the cylinder head. The injectors use spring-loaded needle valves that open rapidly under high hydraulic pressure to atomize the fuel directly into the combustion bowl as a fine spray.

The lubrication system is driven by a gear-type oil pump located in the timing case, powered by the lower idler gear of the crankshaft. It features an integral plate-type engine oil cooler and a dual-element, full-flow spin-on oil filter assembly. To manage thermal loads on internal moving components, the cylinder block is equipped with dedicated internal piston cooling jets. These nozzles continuously spray lubricating engine oil directly onto the interior surfaces of the pistons to dissipate heat from the combustion crowns. Crankcase ventilation is handled via a closed-circuit breather setup to manage emissions.

The engine uses a pressurized, liquid-jacket cooling design managed by a gear-driven centrifugal water pump. The water pump is integrated into the timing gear layout, receiving drive directly from the fuel injection pump gear. Temperature regulation is controlled by an integrated bypass thermostat housing assembly. System fluid paths direct coolant from the water pump through the engine block, oil cooler, and cylinder head jackets before returning to the radiator or heat exchanger system.

General Technical Data

Engine Specifications

Engine Model ............... Caterpillar 3056E
Engine Type ............... 4-cycle inline 6-cylinder direct injection 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) ............... 366 (5.99)
Rated Engine Power (Industrial), hp (kW) ............... 100-175 (75-130)
Rated Engine Power (Agricultural), hp (kW) ............... 110-160 (82-119)
Rated Engine Power (Generator), hp (kW) ............... 80-150 (60-112)
Rated Engine Speed (Industrial), rpm ............... 2200-2400
Rated Engine Speed (Agricultural), rpm ............... 2200-2400
Rated Engine Speed (Generator), rpm ............... 1800-2200
Peak Torque ............... 450-650 Nm (332-480 lb-ft) at 1400-1700 rpm
Idle speed ............... 750-850 rpm
Aspiration Type ............... Turbocharged
Operating Speed ............... 2400 rpm
Compression Ratio ............... 17.0:1-18.0:1
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
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 ............... Distributor
Fuel System Control ............... ADEM ECM
Governor Type ............... Electronic
Injection Pressure, bar ............... 1000
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 41-45 (1050-1150)
Overall Width, in (mm) ............... 28-31 (720-800)
Overall Height, in (mm) ............... 37-41 (950-1050)
Dry Weight, lbs (kg) ............... 1145-1435 (520-650)

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 ............... 300-420 kPa (44-61 psi)
Idle pressure ............... 100-150 kPa (15-22 psi)
Intake Valve Clearance, in (mm) ............... 0.008-0.010 (0.20-0.25)
Exhaust Valve Clearance, in (mm) ............... 0.012-0.014 (0.30-0.35)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CI-4 or higher
Engine Oil Capacity, qts (L) .................. 13.7-16.9 (13.0-16.0)
Coolant Capacity, qts (L) ............... 21.0-26.0 (20.0-24.7)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 250 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 ............... As required

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ................ 3.9370-3.9380 (100.000-100.025)
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) ................ 0.3528-0.3533 (8.960-8.975)
Exhaust Valve Stem Outside Diameter, in (mm) ................ 0.3522-0.3528 (8.945-8.960)
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) ................ 0.0010-0.0025 (0.025-0.065)
Exhaust Valve Stem to Guide Clearance, in (mm) ................ 0.0015-0.0031 (0.040-0.080)
Intake Valve Spring Free Length, in (mm) ................ 1.9213 (48.80)
Exhaust Valve Spring Free Length, in (mm) ................ 1.9213 (48.80)
Intake Cam Height, in (mm) ................ 1.8590-1.8670 (47.22-47.42)
Exhaust Cam Height, in (mm) ................ 1.8590-1.8670 (47.22-47.42)
Piston Pin Outside Diameter, in (mm) ................ 1.5000-1.5003 (38.100-38.107)
Piston Pin to Piston Bore Clearance, in (mm) ................ 0.0003-0.0009 (0.008-0.023)
Top Ring Side Clearance, in (mm) ................ 0.0024-0.0041 (0.060-0.105)
Second Ring Side Clearance, in (mm) ................ 0.0020-0.0037 (0.050-0.095)
Oil Ring Side Clearance, in (mm) ................ 0.0016-0.0033 (0.040-0.085)
Top Ring End Gap, in (mm) ................ 0.0110-0.0197 (0.280-0.500)
Second Ring End Gap, in (mm) ................ 0.0157-0.0276 (0.400-0.700)
Oil Ring End Gap, in (mm) ................ 0.0118-0.0236 (0.300-0.600)

Tightening Torque Specs

Cylinder head bolts ............... 160-180 Nm (118-133 lb-ft)
Main bearing caps ............... 200-230 Nm (148-170 lb-ft)
Connecting rod bolts ............... 95-115 Nm (70-85 lb-ft)
Flywheel bolts ............... 180-210 Nm (133-155 lb-ft)
Crankshaft pulley bolt ............... 280-320 Nm (207-236 lb-ft)
Oil drain plug ............... 40-55 Nm (30-41 lb-ft)
Injector hold-down bolts ............... 25-30 Nm (18-22 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 3056T Specs
  

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