Cat 3116 Specifications
| Engine Model: Caterpillar 3116 |
| Engine Type: 4-cycle inline 6-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 403 cu.in (6.6 L) |
| Rated Engine Power: 140-300 Hp (104-224 kW) at 2200 rpm |
| Aspiration Type: Naturally aspirated |
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The Caterpillar 3116 is a mid-range,
mechanically governed or electronically influenced (early transitional
systems) inline six-cylinder diesel engine widely used in medium-duty
trucks, construction machinery, marine applications, and industrial
power units. Introduced in the late 1980s as part of Caterpillar’s 3100
engine family, the 3116 was designed to provide improved fuel
efficiency, lower emissions, and reduced weight compared to older CAT
engines like the 3208. The engine became known for its compact size,
good power-to-weight ratio, and long service life when maintained
properly.
While the earliest versions were purely mechanical, many later variants
integrated electronic control components for enhanced timing accuracy
and emissions compliance. The 3116’s strong cast-iron structure,
advanced fuel-injection technology for its era, efficient turbocharging,
and durable rotating assembly allowed it to serve reliably across
construction, marine, and on-highway platforms. It remains widely
supported due to strong parts availability and a large global population
still in service.
The Caterpillar 3116 is a four-stroke, water-cooled, direct-injection
inline six-cylinder diesel engine. Displacement is 6.6 liters (403 cubic
inches). Bore is 105 mm (4.13 in) and stroke is 127 mm (5.00 in),
forming a long-stroke configuration ideal for torque production.
Compression ratio varies by model, typically between 16.0:1 and 17.0:1.
Power ratings differ depending on
calibration:
– Truck versions: 170–250 hp (127–186 kW) at 2,200–2,600 rpm
– Construction/industrial: 140–215 hp (104–160 kW)
– Marine propulsion: 150–300 hp (112–224 kW) depending on duty rating
Peak torque generally ranges from: 600–900 Nm (443–664 lb-ft) at
1,400–1,600 rpm. Idle speed is usually 600–700 rpm. Governed maximum
speed ranges from 2,200 to 2,600 rpm. Firing order is 1-5-3-6-2-4.
The crankshaft is forged steel, fully counterweighted, and supported by
seven main bearings. Pistons are high-strength aluminum alloy with steel
reinforcing struts and machined combustion bowls. Connecting rods are
forged steel with replaceable bearings. The camshaft is gear-driven and
mounted in the block.
The cylinder block is a heavy cast-iron structure designed for high
rigidity and long-term endurance. Parent-bore cylinders are cast
directly into the block rather than using removable liners. Coolant
passages encircle each cylinder, enhancing heat dissipation and reducing
the risk of localized hot spots. The crankcase incorporates deep ribbing
for increased stiffness under high load.
The cylinder head is a single cast-iron piece incorporating
direct-injection combustion chambers. The 3116 typically uses four
valves per cylinder—two intake and two exhaust—to improve air handling
and combustion efficiency. Valves are actuated by rocker arms and
pushrods.
General 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 3116 uses a mechanical unit-injector fuel system actuated by the
camshaft. Each injector is pressurized by its own plunger powered by the
camshaft lobes. Fuel delivery and timing are controlled mechanically,
although some late pre-HEUI variants incorporate electronic influence.
Fuel is drawn through a water separator and fine-element filters before
reaching the injectors. Injection pressures exceed 1,000 bar at the
injector tip, ensuring efficient atomization.
Fuel system maintenance:
– Replace fuel filters every 250–300 hours
– Drain water separator regularly
– Inspect injectors at 1,000–1,500-hour intervals
– Calibrate mechanical governors as required.
A high-capacity gear-driven oil pump circulates oil through the
full-flow filter and oil galleries. Lubrication targets include the
crankshaft, connecting rods, camshaft bearings, rocker assemblies, and
turbocharger bearings.
Oil capacity: 18–22 liters (19–23 qt)
Normal oil pressure: 300–450 kPa (44–65 psi)
Idle oil pressure: 100–150 kPa (15–22 psi).
Cooling is achieved via a belt-driven centrifugal water pump circulating
coolant through block, head, and, in some applications, aftercooler
cores. Thermostat opens at 82°C (180°F) and is fully open by 95°C
(203°F).
Cooling capacity: typically 20–28 liters (21–29 qt)
System pressure: 70–90 kPa (10–13 psi)
| Intake and Exhaust Systems |
Turbocharged versions use a single turbocharger with optional air-to-air
aftercooling. Heavy-duty models include two-stage filtration, cyclone
pre-cleaners, or oil-bath filters.
Exhaust manifolds are cast iron, designed for high thermal cycling.
| Electrical and Starting Systems |
Available in 12-volt or 24-volt configurations depending on application.
Alternators output 55–120 amps. Starters range from 3–5 kW. Sensors vary
by model year and may include coolant temperature, oil pressure, and
speed sensors.
The engine can support:
– PTO drives
– Hydraulic pumps
– Marine gearboxes
– Industrial belt-driven equipment
– Generator heads
Approximate dimensions:
– Length: 1,050–1,150 mm (41–45 in)
– Width: 780–880 mm (31–35 in)
– Height: 1,000–1,080 mm (39–43 in)
Dry weight: 800–900 kg (1,764–1,984 lb).
– Oil/filter: every 250 hours
– Fuel filter: 250–300 hours
– Air filter: inspect every 50 hours
– Coolant: replace every 2 years
– Valve lash: adjust every 1,000 hours
– Injector service: 1,000–1,500 hours
– Compression test: 2,000 hours.
– Cylinder head bolts: 170–190 Nm (125–140 lb-ft)
– Main bearing caps: 200–230 Nm (148–170 lb-ft)
– Connecting rods: 110–130 Nm (81–96 lb-ft)
– Flywheel bolts: 180–210 Nm (133–155 lb-ft)
– Crankshaft pulley bolt: 350–400 Nm (258–295 lb-ft)
– Oil drain plug: 40–55 Nm (30–41 lb-ft)
– Injector hold-downs: 25–30 Nm (18–22 lb-ft).
The Caterpillar 3116 has been widely used
in:
– Freightliner and GMC medium-duty trucks
– School buses and transit buses
– CAT loaders and industrial machinery
– Marine auxiliary and propulsion engines
– Construction equipment
– Municipal and utility vehicles.
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