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Mitsubishi 4N14 Specifications
| Engine Model: Mitsubishi 4N14 |
| Engine Type: 4-cycle inline 4-cylinder full-pressure lubrication liquid-cooled diesel |
| Total Displacement: 138.4 cu.in (2.26 L) |
| Rated Engine Power: 148-177 Hp (110-132 kW) at 4000 rpm |
| Fuel System Type: High-pressure common-rail fuel injection |
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| General Technical Data |
The Mitsubishi 4N14 is a 2.2-liter inline-four turbocharged diesel engine introduced in the late 2000s as part of Mitsubishi’s modern clean-diesel initiative. Designed to meet increasingly strict emissions regulations in Europe and Asia, the 4N14 incorporates advanced technologies such as common-rail direct injection, variable-geometry turbocharging, aluminum-alloy construction, low-friction components, and a sophisticated exhaust after-treatment system.
It provides strong low-end torque, excellent
fuel economy, and lower emissions compared to older Mitsubishi diesel
engines. The engine is engineered for smooth operation, high durability,
and quiet combustion characteristics. Workshop technicians appreciate
its robust build, efficient thermal management, and ease of access to
major service points, although the emissions-control system requires
disciplined maintenance.
The Mitsubishi 4N14 has a displacement of 2,268 cc, equivalent to 138.4
cubic inches. Bore measures approximately 86.0 mm (3.39 inches), while
stroke is around 97.6 mm (3.84 inches). This long-stroke design supports
high torque at low rpm. Compression ratio ranges between 14.9 to 1 and
15.5 to 1 depending on model and emissions calibration. Power output
typically ranges from 148 to 177 horsepower (110 to 132 kW) at around
3,500 to 4,000 rpm.
Peak torque is achieved between 360 and 380 Nm
(265 to 280 lb-ft) at roughly 1,500 to 2,750 rpm. Idle speed averages
750 rpm. Redline normally sits around 4,500 rpm. The firing order is
1-3-4-2. The engine uses a variable-geometry turbocharger,
electronically controlled common-rail injection, and advanced EGR and
DPF systems to meet emissions standards.
The cylinder block is constructed from lightweight aluminum alloy with
cast-in iron cylinder liners. The aluminum design reduces engine mass,
improving vehicle efficiency and weight distribution. The crankshaft is
forged steel, fully counterweighted, and supported by five main bearings
for smooth operation. Pistons are high-strength aluminum alloy with
steel insert ring carriers to withstand elevated combustion pressures
typical of modern diesel engines.
The ring pack includes two compression rings
and one oil-control ring, optimized for turbocharged diesel operation.
Connecting rods are forged steel with full-floating wrist pins designed
for high durability. Internal oil galleries cast into the block provide
uniform lubrication to the crankshaft, connecting rods, piston pins, and
cylinder walls. The block is engineered to minimize vibration and noise
through high structural rigidity and optimized rib placement. Workshop
tasks include block inspection for wear, liner condition, and crankshaft
straightness.
The cylinder head is cast aluminum alloy and features double overhead
camshafts operating four valves per cylinder. This 16-valve
configuration improves airflow and combustion efficiency. The combustion
chambers are designed to promote swirl and controlled fuel-air mixing
for efficient diesel ignition. Intake and exhaust valves are made from
heat-resistant alloys suitable for high thermal loads.
Valve actuation uses roller-type rocker arms with hydraulic lash adjusters to eliminate manual valve clearance adjustments. The camshafts are driven by a timing chain system engineered for long service life. The cylinder head includes coolant passages designed for even heat distribution, critical in a high-compression turbocharged diesel. Workshop procedures include camshaft inspection, valve-seal replacement, head resurfacing, and compression testing.
| Fuel System |
The 4N14 uses a high-pressure common-rail direct-injection system. A low-pressure electric fuel pump delivers fuel to a high-pressure pump mounted on the engine. This pump increases fuel pressure to approximately 160 to 180 Mpa, or 23,000 to 26,000 psi, depending on load. Piezoelectric injectors or high-precision solenoid injectors deliver fuel directly into the combustion chamber in multiple pulses per stroke.
This allows fine control of combustion timing, emissions, and fuel economy. The ECU monitors crank-angle position, fuel pressure, air mass, boost pressure, and exhaust gas composition to regulate injection patterns. Recommended fuel is high-quality low-sulfur diesel. Workshop tasks include injector testing, common-rail pressure checks, high-pressure pump inspection, and fuel-filter replacement.
| Lubrication System |
The lubrication system is a full-pressure wet-sump design powered by a crankshaft-driven oil pump. Oil is drawn through a pickup strainer, filtered by a full-flow filter, and circulated through galleries to lubricate the crankshaft, connecting rods, camshafts, turbocharger bearings, and valvetrain components. Piston cooling jets spray oil onto the underside of the piston crowns to control temperature.
Oil capacity ranges between 5.8 and 6.5 liters (6.1 to 6.9 US quarts) depending on vehicle application. Mitsubishi recommends fully synthetic oils such as 5W 30 meeting diesel-specific standards. Oil pressure typically ranges between 300 and 400 kPa (44 to 58 psi). Workshop procedures include oil-pressure testing, turbocharger oil-line inspection, and PCV-system servicing.
| Cooling System |
The cooling system uses a belt-driven water pump, aluminum radiator, electric cooling fans, thermostat, and coolant expansion reservoir. Coolant circulates through the block, cylinder head, and turbocharger housing. The thermostat begins opening at approximately 82 C (180 degrees F) and reaches full flow near 95 C (203 degrees F). Total coolant capacity generally ranges from 7.0 to 8.0 liters (7.4 to 8.5 US quarts).
Cooling-system pressure typically ranges between 12 and 15 psi. The cooling system is engineered to manage high thermal loads associated with turbocharged diesel combustion. Workshop tasks include coolant replacement, radiator cleaning, hose inspection, thermostat evaluation, and checking for coolant pump wear.
| Intake and Exhaust Systems |
The induction system includes an air-cleaner housing, intake ducting, intercooler, and intake manifold. Air is compressed by a variable-geometry turbocharger that adjusts vane position to maintain optimal boost across the rpm range. The compressed air is cooled by an intercooler before entering the cylinders. The exhaust system includes a high-temperature exhaust manifold feeding the turbocharger.
Downstream of the turbocharger, exhaust gas passes through oxidation catalysts, EGR components, and a diesel particulate filter. Workshop tasks include turbocharger inspection, intercooler leak testing, exhaust-flow analysis, and DPF regeneration or cleaning if required. Proper operation of these systems ensures emissions compliance and stable performance.
| Electrical System |
Diesel engines do not use spark ignition; instead, combustion is achieved through high compression and direct injection. The ECU controls injection timing based on engine load, rpm, temperature, and emissions requirements. Glow plugs assist in cold starting by preheating the combustion chamber. The alternator typically outputs between 100 and 130 amperes.
The starter motor is a high-torque reduction-gear type. Electrical diagnostics involve checking glow-plug resistance, alternator output, sensor voltages, and ECU fault codes. Sensors include crank-angle, cam-angle, air-mass, manifold-pressure, coolant-temperature, DPF sensors, and exhaust-gas-temperature sensors.
| Other Systems |
Additional systems include exhaust-gas recirculation to reduce nitrogen oxides, diesel particulate filtration for soot control, oxidation catalysts, swirl-control valves in some versions, and turbocharger wastegate or vane actuators.
The PCV system manages crankcase vapors and reduces emissions. Engine mounts use hydraulic damping to minimize vibration transfer. Workshop service includes EGR cleaning, DPF regeneration, turbo-actuator calibration, and PCV-valve inspection.
| Dimensions and Weight |
The 4N14 engine is compact for a diesel of its displacement. Length measures approximately 650 mm (25.6 inches). Width ranges from 600 to 630 mm (23.6 to 24.8 inches). Height is about 700 mm (27.6 inches). Dry weight typically falls between 155 and 175 kg (342 to 386 lbs). The aluminum block reduces overall mass while maintaining structural rigidity.
| Maintenance Data |
Routine maintenance includes engine-oil and filter replacement every 10,000 to 15,000 km (6,000 to 9,000 miles). Air-filter replacement is recommended every 20,000 km. Fuel filters should be replaced every 20,000 to 30,000 km due to the precision fuel system. Coolant replacement occurs every 40,000 km or every two years.
Glow plugs should be checked during each major service. Workshop tasks include injector testing, high-pressure pump inspection, EGR cleaning, DPF servicing, turbocharger inspection, and intake-system cleaning. Proper maintenance prevents carbon buildup, improves fuel efficiency, and ensures long-term durability.
| Tightening Torques |
Cylinder-head bolts tighten in multiple stages beginning near 30 Nm (22 lb-ft), followed by angle tightening. Main-bearing-cap bolts tighten to 70 to 80 Nm (52 to 59 lb-ft). Connecting-rod bolts torque to approximately 40 Nm (30 lb-ft) plus angle.
Glow plugs tighten to around 12 Nm (9 lb-ft). Oil-drain plugs tighten to roughly 35 Nm (26 lb-ft). Intake-manifold bolts require about 22 to 25 Nm, while exhaust-manifold bolts require 25 to 30 Nm. Turbocharger-mounting bolts require 40 to 50 Nm.
| Vehicle Applications |
The Mitsubishi 4N14 engine has been used in vehicles such as the Mitsubishi Outlander, ASX, and RVR, as well as regional variants and commercial platforms. Its combination of strong torque, low emissions, and efficient operation made it well suited for crossovers, compact SUVs, and multipurpose vehicles. The engine remains favored for its durability, fuel economy, and advanced diesel technology.
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