Mitsubishi 4M41 Specifications
| Engine Model: Mitsubishi 4M41 |
| Engine Type: 4-cycle 4-cylinder DOHC 16-valve turbocharged liquid-cooled diesel |
| Total Displacement: 195.3 cu.in (3.20 L) |
| Rated Engine Power: 165-200 Hp (121-147 kW) at 3800 rpm |
| Fuel System Type: Direct injection or Common rail direct injection |
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The Mitsubishi 4M41 is a 3.2-liter, inline-four,
direct-injection diesel engine introduced as the successor to the 4M40. Produced
from 1999 onwards, this powerplant represented a significant advancement in
Mitsubishi’s diesel technology, serving as the flagship engine for the third and
fourth generations of the Mitsubishi Pajero (Montero) and high-specification
variants of the L200 Triton. The 4M41 was Mitsubishi’s first large-scale
production diesel engine to feature a 16-valve, dual overhead camshaft (DOHC)
cylinder head, a configuration that improved volumetric efficiency and enabled
higher specific output compared to the SOHC 4M40.
The engine evolved substantially over its production life. Early variants
utilized a mechanical or electronically controlled direct injection (DI) system
with a conventional injection pump, delivering robust low-end torque suitable
for off-road applications. From approximately 2006 onward, the 4M41 was upgraded
to a high-pressure common rail (DI-D) system, incorporating a variable geometry
turbocharger (VGT) to enhance power delivery across a broader engine speed
range.
The engine utilizes a timing chain for valve actuation and a cast iron block
with an aluminum cylinder head. The 4M41 is recognized for its durability and
high torque output, making it suitable for heavy-duty applications in both
passenger and commercial vehicles.
The 4M41 is a water-cooled, four-stroke, turbocharged and intercooled diesel
engine configured for longitudinal mounting in rear-wheel-drive and
four-wheel-drive vehicle architectures. The engine is available in two primary
configurations: an early direct injection (DI) variant with a mechanical or
electronically governed injection pump, and a later common rail (DI-D) variant
with variable geometry turbocharging.
Engine Type: Inline-4, 4-cycle, water-cooled, turbocharged diesel.
Displacement: 3,200 cc (195.3 cu.in).
Bore and Stroke: 98.5 mm (3.88 in) x 105.0 mm (4.13 in).
Valvetrain: DOHC, 16-valve (4 valves per cylinder) with chain drive.
Firing Order: 1-3-4-2.
Compression Ratio: 16.0:1 to 17.0:1 (variant and year dependent).
Idle Speed: 700 ± 50 rpm.
Maximum Engine Speed: 4,400 rpm (governor limited).
Early Direct Injection (DI) Variant
Aspiration: Turbocharged and intercooled with fixed-geometry turbocharger.
Fuel System: Direct injection with mechanical or electronically governed in-line
pump.
Maximum Power: 121 kW (165 hp) at 3,800 rpm.
Maximum Torque: 351 Nm (259 lb-ft) at 2,000 rpm.
Late Common Rail (DI-D) Variant
Aspiration: Turbocharged and intercooled with variable geometry turbocharger
(VGT).
Fuel System: Common rail direct injection.
Maximum Power: 147 kW (200 hp) at 3,800 rpm.
Maximum Torque: 441 Nm (325 lb-ft) at 2,000-2,200 rpm.
The cylinder block is constructed from gray cast iron,
a material selected for its exceptional rigidity, vibration-damping properties,
and long-term dimensional stability under the elevated cylinder pressures
generated by direct injection diesel combustion. The closed-deck design provides
robust support for the cylinder head gasket and minimizes bore distortion under
high thermal and mechanical loads. The long-stroke architecture - with a stroke
of 105.0 mm (4.13 in) relative to a bore of 98.5 mm (3.88 in) - emphasizes
low-end torque generation, a critical characteristic for off-road and heavy-duty
applications.
Cast-in-place cylinder bores are machined directly into the iron casting. The
block incorporates five main bearing webs with two-bolt main bearing caps. The
crankshaft is supported by five bearings and is constructed from forged steel to
withstand the high cylinder pressures of diesel combustion. A stamped steel oil
pan is sealed to the lower crankcase, providing the oil reservoir. The block
design incorporates substantial ribbing around the main bearing area and
cylinder skirts to minimize flexure under load.
Block Material: Gray cast iron
Bore Diameter (finished): 98.5 mm (3.88 in)
Main Bearing Caps: Cast iron, two-bolt design
Cylinder Bore Deformation Limit: 0.05 mm (0.0020 in)
Compression Pressure (standard): 3.0 MPa (435 psi)
Compression Pressure (minimum): 2.1 MPa (305 psi)
The cylinder head is manufactured from aluminum alloy,
a selection that reduces overall engine mass and improves heat dissipation from
the combustion chambers. The DOHC valvetrain actuates sixteen valves - four
valves per cylinder - through roller rocker arms and hydraulic lash adjusters.
The four-valve configuration improves volumetric efficiency, allowing greater
airflow into the combustion chamber and more efficient evacuation of exhaust
gases compared to two-valve designs. The centrally located injector position
optimizes fuel spray distribution within the combustion chamber.
The camshafts are driven by a roller chain from the crankshaft, with an
automatic hydraulic tensioner maintaining chain tension. Hydraulic lash
adjusters eliminate the need for manual valve clearance adjustments throughout
the engine’s service life. The combustion chambers are of a re-entrant bowl
design machined into the piston crown, a configuration that promotes turbulence
and efficient mixing of fuel and air. The engine is of interference design; in
the event of timing chain failure or significant timing deviation,
valve-to-piston contact occurs.
Head Material: Aluminum alloy
Valve Configuration: DOHC, 4 valves per cylinder with roller rocker arms
Valve Diameter (Intake): 32.0 mm (1.26 in)
Valve Diameter (Exhaust): 28.0 mm (1.10 in)
Valve Stem Diameter: 6.0 mm (0.24 in)
Valve Seat Angle: 45 degrees
Valve Clearance (cold): Hydraulic lash adjusters
The 4M41’s fuel system evolved significantly over its
production life. The early DI variant employs a direct injection system with a
mechanically governed in-line injection pump. Fuel is delivered to the injectors
at high pressure through individual injection lines. The injection timing is
controlled by the pump’s internal governor and can be adjusted mechanically.
This system provides reliable operation with tolerance for varying fuel quality.
The later DI-D variant utilizes a common rail direct injection system. A
high-pressure fuel pump, driven by the timing chain or gear train, delivers fuel
to a common rail accumulator at pressures up to 160 MPa (23,200 psi). The rail
distributes pressurized fuel to solenoid or piezoelectric injectors, which are
controlled by the engine control unit (ECU). The system enables multiple
injection events per combustion cycle - including pilot, main, and post
injections - to reduce combustion noise, lower particulate emissions, and
improve cold-start performance. A variable geometry turbocharger (VGT) works in
conjunction with the common rail system to optimize boost pressure across the
engine speed range.
Injection Type (Early): Direct injection with mechanical in-line pump
Injection Type (Late): Common rail direct injection
Injection Pressure (Late): 160 MPa (23,200 psi) maximum
Fuel Requirement: Diesel fuel meeting applicable standards
Fuel Cutoff: 4,400 rpm
The lubrication system is a fully pressurized, wet-sump
design utilizing a gear-type oil pump mounted to the front of the crankshaft.
The oil pump draws lubricant from the stamped steel oil pan through a mesh
strainer and circulates it through a full-flow, replaceable oil filter before
entering the main oil gallery. A piston cooling oil jet system is incorporated
to direct a stream of oil toward the underside of each piston crown, managing
thermal loads associated with the high compression ratio and turbocharging.
From the main gallery, pressurized oil is distributed to the crankshaft main
bearings, connecting rod bearings, camshaft bearings, hydraulic lash adjusters,
timing chain tensioner, and turbocharger bearing housing. A pressure relief
valve integrated into the oil pump maintains system pressure within operational
limits to prevent over-pressurization during cold starts.
Oil Type: SAE 5W-30, 5W-40, or 15W-40 (API CI-4, CJ-4, or higher)
Oil Capacity (with filter): 7.5-9.3 liters (7.9-9.8 US qt) (variant dependent)
Oil Pressure (at 3,000 rpm): 350-450 kPa (50.8-65.3 psi)
Oil Pump Type: Gear-type, crankshaft-driven
Oil Filter Type: Full-flow, spin-on or cartridge-type
The cooling system is a pressurized, liquid-cooled
design employing a cross-flow aluminum radiator with an engine-driven cooling
fan and viscous clutch, supplemented by an electric fan on some applications. A
centrifugal-type water pump, driven by the accessory belt or timing chain,
circulates coolant through the engine block, cylinder head, turbocharger center
housing, intercooler (on intercooled variants), and heater core.
A wax-pellet thermostat regulates coolant flow to maintain optimal operating
temperature, with a bypass circuit that allows the engine to warm rapidly by
circulating coolant only within the engine until the thermostat opens. The
cooling system is sized to manage the thermal load of the high-output diesel
engine under sustained load conditions, such as towing or off-road operation.
Coolant Type: Ethylene-glycol based antifreeze with corrosion inhibitors
Coolant Capacity: 9.0-10.5 liters (9.5-11.1 US qt) (variant dependent)
Thermostat Opening Temperature: 80-85 °C (176-185 °F)
Thermostat Full-Open Temperature: 95 °C (203 °F)
Radiator Cap Pressure: 100-120 kPa (14.5-17.4 psi)
Water Pump Type: Centrifugal, accessory belt or timing chain-driven
| Intake and Exhaust Systems |
Intake System: Cast aluminum intake manifold with
individual runners per cylinder. The turbocharged air passes through the
intercooler before entering the intake manifold. The intake system incorporates
an air cleaner housing with a dry-type paper filter element.
Exhaust System: Cast iron exhaust manifold with integrated turbocharger mounting
flange. On VGT variants, the manifold is designed to accommodate the variable
geometry mechanism. The exhaust system incorporates an oxidation catalytic
converter and, on later variants, a diesel particulate filter (DPF) to meet
emissions regulations.
Turbocharger System: The early DI variant utilizes a
fixed-geometry turbocharger with a wastegate to regulate boost pressure. The
later DI-D variant employs a variable geometry turbocharger (VGT), which adjusts
turbine nozzle vanes to optimize boost response across the engine speed range,
reducing turbo lag and improving low-end torque. Maximum boost pressure ranges
from 0.9 to 1.2 bar (13.1-17.4 psi) depending on variant. An air-to-air
intercooler is mounted in front of the radiator to reduce intake air
temperature.
Timing Drive: A roller chain drives the camshafts from the crankshaft sprocket.
An automatic hydraulic tensioner maintains chain tension. The timing chain is
designed for extended service life, though the upper chain guide is a known wear
item requiring inspection at 100,000 km (60,000 mi) intervals.
Overall Length: 770 mm (30.3 in)
Overall Width: 700 mm (27.6 in)
Overall Height: 780 mm (30.7 in)
Dry Weight (complete engine): 260-280 kg (573-617 lb)
Oil Change Interval: 10,000 km (6,200 mi) under normal
driving conditions; 5,000 km (3,100 mi) under severe conditions. Oil Filter
Change: At every oil change. Timing Chain Inspection: Inspect upper guide wear
at 100,000 km (60,000 mi); no scheduled replacement for chain under normal
conditions.
Engine Coolant Replacement: 40,000 km (25,000 mi) or 2 years. Glow Plug
Inspection: Check at each major service; replace as required. Drive Belt
(Accessory) Inspection: Every 10,000 km (6,200 mi) for tension, cracking, and
glazing.
Air Filter Replacement: 20,000 km (12,500 mi) or as indicated by inspection.
Fuel Filter Replacement: 20,000 km (12,500 mi). Valve Clearance: Hydraulic lash
adjusters; no adjustment required. Idle Speed: Non-adjustable; controlled by
ECU.
Cylinder Head Bolts (cold), 1st pass: 50 Nm (37 lb-ft).
Cylinder Head Bolts (cold), 2st pass: 100 Nm (74 lb-ft).
Main Bearing Cap Bolts: 20 Nm (15 lb-ft) plus 90° rotation.
Connecting Rod Cap Bolts: 30 Nm (22 lb-ft) plus 90° rotation.
Camshaft Bearing Cap Bolts: 18-22 Nm (13-16 lb-ft).
Intake Manifold Bolts: 18-22 Nm (13-16 lb-ft).
Exhaust Manifold Nuts: 25-30 Nm (18-22 lb-ft).
Turbocharger Mounting Nuts: 30-35 Nm (22-26 lb-ft).
Glow Plugs: 20-25 Nm (15-18 lb-ft).
Oil Pan Bolts: 8-10 Nm (71-89 lb-in).
Water Pump Bolts: 18-22 Nm (13-16 lb-ft).
Timing Chain Tensioner: 30-35 Nm (22-26 lb-ft).
Crankshaft Pulley Bolt: 323 Nm (238 lb-ft).
Flywheel / Drive Plate Bolts: 70-75 Nm (52-55 lb-ft).
Injection Pump Drive Gear Nut (early): 45-50 Nm (33-37 lb-ft).
The Mitsubishi 4M41 engine was utilized across a range
of Mitsubishi passenger and commercial vehicles, serving as the flagship diesel
powertrain for the Pajero and high-specification L200 Triton models.
Mitsubishi Pajero / Montero (V60, V70, V80 series): Third and fourth generations
with 3.2 DI-D engine.
Mitsubishi L200 / Triton (KT, KU, MQ series): High-specification variants with
3.2 DI-D engine.
Mitsubishi Challenger / Montero Sport: Select markets with 3.2 DI-D engine.
Mitsubishi Canter: Light truck applications in certain markets.
Hyundai Terracan: Select diesel variants utilizing the 4M41 engine under
license.
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