Cat 3306B Specifications
| Engine Model: Caterpillar 3306B |
| Engine Type: 4-cycle inline 6-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 638 cu.in (10.5 L) |
| Rated Engine Power: 150-315 Hp (112-235 kW) at 2100 rpm |
| Aspiration Type: Naturally aspirated or turbocharged |
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The Caterpillar 3306B is one of CAT’s most
iconic mid-displacement heavy-duty diesel engines, widely used in
construction, industrial, agricultural, marine, and generator
applications. It evolved from the earlier 3306 platform, which
established a reputation for extraordinary durability, long overhaul
intervals, and ease of maintenance. The 3306B adds refinements in fuel
delivery, cooling efficiency, and turbocharging, improving performance
and fuel economy while maintaining the legendary simplicity and
reliability of the base engine.
The engine’s cast-iron block, wet-sleeve construction, robust rotating
assembly, and mechanical fuel system make it extremely tolerant of harsh
working conditions and prolonged high-load operation. Its ability to run
for tens of thousands of hours with routine maintenance made it a staple
in dozers, loaders, excavators, compressors, pumps, and generator sets
worldwide.
The Caterpillar 3306B is a four-stroke, water-cooled, turbocharged or
naturally aspirated inline six-cylinder diesel engine. Its displacement
is 10.5 liters (638 cubic inches). Bore is 121 mm (4.76 in), while
stroke is 152 mm (6.00 in). This long-stroke architecture produces high
torque at low-to-mid engine speeds and provides excellent fuel
efficiency for heavy-duty cycles.
Compression ratios vary:
— Naturally aspirated: approximately 16.0:1
— Turbocharged: approximately 15.0:1
Power ratings (application dependent):
— Industrial/Construction: 150–300 hp (112–224 kW) @ 1,800–2,200 rpm
— Agricultural: 140–260 hp (104–194 kW)
— Marine: 150–315 hp (112–235 kW)
— Generator sets: 100–250 kW @ 1,500–1,800 rpm
Peak torque: 700–1,150 Nm (516–848 lb-ft) @ 1,200–1,500 rpm. Idle speed:
typically 650–750 rpm. Governed speed: 1,800–2,200 rpm. Firing order:
1-5-3-6-2-4.
The crankshaft is forged steel, fully counterweighted, and supported by
seven main bearings. Pistons are cast aluminum or steel crown composite
designs with reinforced combustion bowls. Connecting rods are forged
steel with replaceable bearings. The camshaft is gear-driven, providing
long-term timing accuracy.
The cast-iron block features heavy ribbing, a deep skirt structure, and
removable wet cylinder sleeves for ease of overhaul. Coolant passages
fully circulate around the liners, minimizing thermal stress. The
block’s rigidity supports consistent bearing alignment under severe
operating loads.
Wet-sleeve features:
— Replaceable liners for multiple rebuild cycles
— Superior cooling around cylinders
— Tight sealing with robust O-ring systems
The cast-iron cylinder head incorporates direct-injection combustion
chambers and four valves per cylinder—two intake and two exhaust. The
valvetrain uses rocker arms actuated by pushrods driven from the
camshaft.
Cold valve-lash settings:
— Intake: 0.38–0.43 mm (0.015–0.017 in)
— Exhaust: 0.64–0.69 mm (0.025–0.027 in)
The head gasket uses fire rings for high-pressure combustion sealing.
Head assembly is engineered for stability during extended heavy-load
operation.
The 3306B employs a mechanical direct-injection fuel system.
Depending
on model:
— Turbo and industrial versions use a mechanical inline pump
— Earlier versions may use a mechanically governed rotary pump
Fuel-system components include:
— Mechanical lift pump
— Primary water separator
— Secondary fine fuel filter
— Mechanical injection pump
— Mechanical multi-hole injectors
Injection pressures typically range from 250 to 350 bar.
Fuel-service requirements:
— Fuel filters: replace every 250–300 hr
— Drain water separator daily
— Injector overhaul: every 1,000–1,500 hr
— Pump timing inspection: every major service interval.
The lubricating system is a full-pressure wet-sump design with a
gear-driven oil pump.
Oil capacity: 18–25 liters (19–26.4 qt)
Operating oil pressure: 300–450 kPa (44–65 psi)
Idle oil pressure: 100–150 kPa (15–22 psi)
Recommended oils: SAE 15W-40 diesel oil (API CI-4 or higher)
Oil change interval: typically 250 hr for industrial applications.
The 3306B uses a belt-driven or gear-driven centrifugal water pump
circulating coolant through the block, head, oil cooler, and radiator.
Thermostat:
— Opening: 82°C (180°F)
— Full open: 95°C (203°F)
Cooling capacity: 28–36 liters (30–38 qt)
System pressure: 70–100 kPa (10–15 psi).
| Intake and Exhaust Systems |
Air intake options:
— Dry dual-stage filters
— Oil-bath filters (extreme dust)
— Canister industrial filters
Turbocharged versions deliver improved torque and power across all
speeds. Aftercooling may be included in certain arrangements.
The exhaust manifold is cast iron, optimized for repeated thermal
cycling.
| Electrical and Starting Systems |
Electrical configurations typically include 12V or 24V systems.
Components:
— Alternator: 35–70 amps
— Starter motor: 3–5 kW
— Temperature, oil-pressure, and speed sensors depending on application
Electronic management systems were not typical on early 3306B engines,
keeping service procedures simple and mechanical.
The 3306B may support:
— Hydraulic pump drives
— PTO drives
— Air compressors
— Generator heads
— Remote cooling packages
— Marine gearboxes.
Approximate dimensions:
— Length: 1,300–1,450 mm (51–57 in)
— Width: 800–900 mm (31–35 in)
— Height: 1,050–1,250 mm (41–49 in)
Dry weight: 1,100–1,300 kg (2,425–2,866 lb).
Standard service intervals:
— Oil and filter: 250 hr
— Fuel filters: 250–300 hr
— Air-filter element: inspect every 50 hr
— Valve adjustment: every 1,000 hr
— Injector inspection: every 1,000–1,500 hr
— Coolant replacement: every 2 years
— Compression test: every 2,000 hr.
— Cylinder head bolts: 300–350 Nm (221–258 lb-ft)
— Main-bearing caps: 400–450 Nm (295–332 lb-ft)
— Connecting-rod bolts: 150–170 Nm (111–125 lb-ft)
— Flywheel bolts: 280–320 Nm (207–236 lb-ft)
— Crankshaft pulley bolt: 450–550 Nm (332–406 lb-ft)
— Oil drain plug: 40–55 Nm (30–41 lb-ft)
— Injector hold-down: 25–30 Nm (18–22 lb-ft).
The Caterpillar 3306B engine is found in:
— Wheel loaders
— Bulldozers (mid-size CAT D-series)
— Excavators
— Graders
— Agricultural tractors
— Industrial compressors
— Generator sets up to 250 kW
— Marine propulsion/auxiliary units
— Oilfield pumping units
— Mining support equipment.
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