Cat 3066 Specifications
| Engine Model: Caterpillar 3066 |
| Engine Type: 4-stroke in-line 6-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 389 cu.in (6.37 L) |
| Rated Engine Power: 138-148 Hp (103-110 kW) at 2100 rpm |
| Fuel System Type: Unit injection |
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The Caterpillar 3066 is a 6.37 L, 6-cylinder,
turbocharged and aftercooled diesel engine renowned for its reliability
and durability in heavy-duty applications. It was specifically
engineered to deliver a high torque rise at medium speeds, which
provides excellent lugging power and productivity in demanding
conditions such as excavating and material handling. This engine
features a direct injection fuel system and a parent bore block design,
making it a robust and serviceable power unit widely used in the
Caterpillar 300 series hydraulic excavators and various industrial
machines.
Engine Type: 4-cycle, in-line, 6-cylinder diesel.
Displacement: 6.37 L (389 cu.in).
Bore and Stroke: 102 mm x 130 mm (4.02 in x 5.12 in) or 104 mm x 125 mm
(varies by serial prefix).
Aspiration: Turbocharged and aftercooled (TA / T).
Combustion System: Direct Injection.
Firing Order: 1-5-3-6-2-4.
Rotation: Counterclockwise (facing flywheel).
Performance Data
Rated Power: 103 kW to 110 kW (138 HP to 148 HP).
Rated Speed: 1800-2100 RPM.
Maximum Torque: 540 Nm to 590 Nm (398-435 lb-ft) @ 1400-1600 RPM.
Idle Speed: 800-1000 RPM.
The cylinder block is a parent bore design, meaning it does not use
replaceable cylinder liners. This configuration requires the block to be
bored to an oversized specification during an overhaul to accommodate
new, oversized pistons. The block is constructed from high-strength cast
iron to provide a rigid foundation for the crankshaft and other rotating
assemblies, ensuring durability under high cylinder pressures.
The engine utilizes an overhead valve (OHV) arrangement. The cylinder
head is a single, cast-iron unit that covers all six cylinders. The
valvetrain consists of 2 valves per cylinder (1 intake, 1 exhaust),
actuated by a camshaft, lifters, pushrods, and rocker arms. This design
prioritizes simplicity, ease of maintenance, and robust reliability in
commercial applications.
The fuel system is a mechanical unit injection system. It is equipped
with an inline injection pump, built to Bosch-style specifications,
which delivers high-pressure diesel fuel to the individual injectors.
The system uses a spin-on fuel filter with an integrated water separator
to protect the precision components from contamination. A hand priming
pump is located on the fuel filter base to assist in priming the system
after filter changes.
Oil Capacity:19.0 to 22.0 L (20.0-23.2 U.S. qt).
Oil Pressure: 45-65 psi (310-448 kPa) at rated speed.
The system uses a gear-driven rotor-type oil pump. The oil filter is a
spin-on, full-flow type located on the side of the engine for convenient
service access. An oil cooler is integrated into the cooling system to
maintain stable lubricant temperatures.
Coolant Capacity: 13.0 L (13.7 U.S. qt) (engine only).
Thermostat: Starts opening at 76.5°C (170°F).
The cooling system features a gear-driven centrifugal water pump and a
corrugated-wave fin, four-row radiator design that facilitates easy
cleaning. A wire mesh screen is mounted in front of the radiator to
prevent debris from clogging the cooling fins.
Electrical System: 24-volt system comprising a heavy-duty starting motor
and a belt-driven alternator (approximately 50A). The system is designed
for reliable cold weather starting, with an optional air intake heater
available for assistance in low ambient temperatures.
Air Intake System: Features a radial seal air cleaner with a
double-layered filter core for superior cleaning efficiency. A
restriction indicator alerts the operator when the filter element
requires service.
Weight (Dry): 520 kg to 560 kg (1,146-1,235 lb).
Overall Length: 1,100 mm (43.3 in)
Overall Width: 700 mm (27.6 in)
Overall Height: 950 mm (37.4 in).
Oil Change Interval: 250-500 hours depending on application and oil
analysis.
Fuel Filter Replacement: 500 hours.
Valve Lash (Clearance): Intake: 0.38 mm (0.015 in); Exhaust: 0.76 mm
(0.030 in) (cold).
Cooling System Protection: Maintain a 1:1 ratio of water to ethylene
glycol antifreeze.
Cylinder Head Bolts: 175-185 Nm (129-137 lb-ft).
Connecting Rod Bolts: 50 Nm (37 lb-ft) + 90° turn.
Main Bearing Caps: 50 Nm (37 lb-ft) + 90° turn.
Flywheel Bolts: 185 Nm (137 lb-ft).
Crankshaft Pulley Nut: 490 Nm (360 lb-ft).
Excavators: Cat 318C, 320, 320B, 320C, 320D, and 321B LCR.
Industrial: Used in medium-duty material handlers, stationary power
units, and various original equipment manufacturer (OEM) installations.
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