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Caterpillar 3306 DITA Engine

The Caterpillar 3306 DITA (Direct Injection, Turbocharged, Aftercooled) is a heavy-duty, 10.5-liter (641 cubic inches) inline-six, four-stroke diesel engine. Widely recognized as one of Caterpillar's most reliable and enduring configurations, it has been extensively utilized in earthmoving equipment, marine propulsion, electrical power generation, and industrial machinery. The design utilizes a cast-iron engine block with replaceable wet cylinder liners. The combination of turbocharging and jacket-water or sea-water aftercooling provides exceptional thermal efficiency, superior fuel economy, and stable high-altitude or high-load operation.

Fuel System Type: High-pressure mechanical direct injection. Injection Pump: Single, centrally mounted V-type mechanical injection pump assembly. It distributes fuel through individual steel lines to mechanical injectors located in each cylinder head. Timing and Regulation: Driven by a mechanical governor with an automatic timing advance unit to adjust injection timing relative to engine speed. Maintenance: The system requires comprehensive manual priming and bleeding via the hand priming pump if air enters the fuel lines.

Lubrication System Type: Full-pressure, wet-sump lubrication system. Components: Gear-driven oil pump, integral oil cooler bypass, and spin-on fluid filters. Service: Standard operation utilizes high-quality 15W-40 diesel-rated engine oil. Cooling System Type: Liquid-cooled, closed-loop configuration. Components: Centrifugal water pump, dual water temperature regulators (thermostats), and a bypass circuit. Application Variants: Industrial models use standard radiators, while marine configurations integrate an engine-mounted heat exchanger alongside a raw-water auxiliary pump.

General Technical Data

Engine Specifications

Engine Model ............... Caterpillar 3306 DITA
Engine Type ............... 4-cycle inline 6-cylinder direct injection liquid-cooled diesel
Number of Cylinders ............... 6
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 4.76 (121.0)
Engine Stroke, in (mm) ............... 6.00 (152.0)
Displacement, cu.in (L) ............... 638 (10.5)
Rated Engine Power, hp (kW) ............... 218-350 (162-260)
Rated Engine Speed, rpm ............... 2000-2200
Peak Torque ............... 750-1200 Nm (553-885 lb-ft) at 1200-1500 rpm
Idle Speed ............... 650-750 rpm
Aspiration Type ............... Turbocharged and Aftercooled
Operating Speed ............... 2000 rpm
Compression Ratio ............... 14.0:1-15.5:1
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 ............... 45-100

Fuel System

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

Dimensions and Weight

Overall Length, in (mm) ............... 51.2-59.1 (1300-1500)
Overall Width, in (mm) ............... 33.5-37.4 (850-950)
Overall Height, in (mm) ............... 41.3-49.2 (1100-1250)
Dry Weight, lbs (kg) ............... 2640-3300 (1200-1500)

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 ............... 345-550 kPa (50-80 psi)
Idle oil pressure ............... 140-275 kPa (20-40 psi)
Intake Valve Clearance, in (mm) ............... 0.015-0.017 (0.38-0.43)
Exhaust Valve Clearance, in (mm) ............... 0.025-0.027 (0.64-0.69)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CF/CH-4 or higher
Engine Oil Capacity, qts (L) .................. 28.4-35.7 (27.0-34.0)
Coolant Capacity, qts (L) ............... 31.5-52.2 (30.0-50.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 300 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) ................ 4.750-4.752 (120.65-120.70)
Crankshaft Journal Outside Diameter, in (mm) ................ 3.4990-3.5000 (88.875-88.900)
Crank Pin Outside Diameter, in (mm) ................ 2.9987-3.0003 (76.167-76.208)
Crankshaft End Play, in (mm) ................ 0.007-0.025 (0.17-0.63)
Intake Valve Stem Outside Diameter, in (mm) ................ 0.3717-0.3725 (9.441-9.462)
Exhaust Valve Stem Outside Diameter, in (mm) ................ 0.3705-0.3713 (9.411-9.431)
Intake Valve Guide Inside Diameter (Installed), in (mm) ................ 0.3734-0.3744 (9.484-9.510)
Exhaust Valve Guide Inside Diameter (Installed), in (mm) ................ 0.3734-0.3744 (9.484-9.510)
Intake Valve Stem to Guide Clearance, in (mm) ................ 0.0009-0.0027 (0.022-0.069)
Exhaust Valve Stem to Guide Clearance, in (mm) ................ 0.0021-0.0039 (0.053-0.099)
Intake Valve Spring Free Length, in (mm) ................ 2.47 (62.7)
Exhaust Valve Spring Free Length, in (mm) ................ 2.47 (62.7)
Intake Cam Height, in (mm) ................ 1.844-1.856 (46.84-47.14)
Exhaust Cam Height, in (mm) ................ 1.844-1.856 (46.84-47.14)
Piston Pin Outside Diameter, in (mm) ................ 1.5011-1.5013 (38.128-38.133)
Piston Pin to Piston Bore Clearance, in (mm) ................ 0.0002-0.0008 (0.005-0.020)
Top Ring Side Clearance, in (mm) ................ 0.0031-0.0051 (0.079-0.130)
Second Ring Side Clearance, in (mm) ................ 0.0024-0.0043 (0.061-0.109)
Oil Ring Side Clearance, in (mm) ................ 0.0016-0.0035 (0.041-0.089)
Top Ring End Gap, in (mm) ................ 0.0170-0.0320 (0.432-0.813)
Second Ring End Gap, in (mm) ................ 0.0150-0.0270 (0.381-0.686)
Oil Ring End Gap, in (mm) ................ 0.0100-0.0220 (0.254-0.559)

Tightening Torque Specs

Cylinder head bolts ............... 270-310 Nm (200-230 lb-ft)
Main-bearing caps ............... 400-450 Nm (295-330 lb-ft)
Connecting-rod bolts ............... 155-175 Nm (114-130 lb-ft)
Flywheel bolts ............... 380-420 Nm (280-310 lb-ft)
Crankshaft pulley bolt ............... 450-500 Nm (332-370 lb-ft)
Oil drain plug ............... 50-70 Nm (37-52 lb-ft)
Injector hold-downs ............... 35-45 Nm (26-33 lb-ft)

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