Mitsubishi 6D22 Specifications
| Engine Model: Mitsubishi 6D22 |
| Engine Type: 4-cycle inline 6-cylinder liquid-cooled diesel |
| Total Displacement: 680.4 cu.in (11.15 L) |
| Rated Engine Power: 225 Hp (168 kW) at 2200 rpm |
| Fuel System Type: Direct injection |
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The Mitsubishi 6D22 is an 11.1-liter, inline-6,
heavy-duty diesel engine produced by Mitsubishi Motors Corporation (MMC)
and later by Mitsubishi Fuso. Introduced in the early 1980s, this
powerplant was designed for commercial vehicles and industrial equipment
requiring sustained high-load operation. The 6D22 engine family includes
naturally aspirated, turbocharged, and turbocharged with intercooler
variants, identified by suffixes such as -T, -TC, -T2, -T3, and -T6.
The engine is most widely recognized for its application in the
Mitsubishi Fuso Super Great heavy-duty trucks, large buses, Kobelco
excavators, and Kato industrial machinery. The Mitsubishi 6D22 combines
a cast iron cylinder block with an overhead valve (OHV) valvetrain and a
mechanical in-line injection pump. Its long stroke and under-square
bore-to-stroke ratio of 130 mm by 140 mm produce substantial low-end
torque, making it suitable for construction, freight, and earthmoving
duties.
The engine displaces 11,149 cc (680.4 cu.in), achieved through bore and
stroke dimensions of 130 mm by 140 mm. This highly undersquare
configuration, with a stroke 10 mm longer than the bore, prioritizes
low-speed torque production over high-rpm power. The compression ratio
varies by aspiration: naturally aspirated versions operate at 17.0:1,
turbocharged (6D22-T) at 16.0:1, and turbocharged with intercooler
(6D22-TC) at 15.5:1. Power output ranges from 146 hp for the naturally
aspirated version to 330 hp for the highest-output turbocharged variant,
the 6D22-T3.
The valvetrain uses pushrods and rocker arms actuated by a camshaft
located in the cylinder block. Mechanical lifters require periodic
manual valve lash adjustment. The fuel system employs a Bosch-style
mechanical in-line injection pump with individual plungers for each
cylinder, generating injection pressures of 21.6 MPa (220 kgf/cm2).
The forced lubrication system uses a gear-type oil pump with a total
capacity of 29 to 31.5 liters (7.7-8.3 gal) including the filter. The
dry weight of the base engine is approximately 980 kg (2,160 lb). When
maintained correctly with 250-hour service intervals, the 6D22
frequently achieves 800,000 to 1,000,000 kilometers (500,000-620,000
miles) in over-the-road truck applications before requiring major
overhaul.
Engine Type: 4-cycle, Overhead Valve (OHV), Inline-6 diesel
Valvetrain: OHV, 12 valves (2 per cylinder) with pushrods and rocker
arms
Aspiration: Naturally Aspirated (6D22)
Aspiration: Turbocharged (6D22-T)
Aspiration: Turbocharged and Intercooled (6D22-TC, -T2, -T3, -T6)
Displacement: 11,149 cc (11.15 L, 680.4 cu.in)
Bore: 130.0 mm (5.118 in)
Stroke: 140.0 mm (5.512 in)
Compression Ratio (6D22): 17.0:1
Compression Ratio (6D22-T): 16.0:1
Compression Ratio (6D22-T2, -T3, -T6): 15.0-15.5:1
Firing Order: 1-5-3-6-2-4
Compression Pressure (Standard): 2.75 MPa (398 psi)
Compression Pressure (Minimum Service Limit): 1.96 MPa (284 psi)
Power Ratings:
6D22 (Naturally Aspirated): 146-225 hp (109-168 kW) @ 1,500-2,200 rpm
6D22-T (Turbo): 216-270 hp (161-201 kW) @ 1,500-2,200 rpm
6D22-T0 (Turbo/Intercooled): 270 hp (199 kW) @ 2,200 rpm
6D22-T1 (Turbo/Intercooled): 285 hp (210 kW)
6D22-T2 (Turbo/Intercooled): 310 hp (228 kW) @ 2,200 rpm
6D22-T3 (Turbo/Intercooled): 330 hp (243 kW)
6D22-T6 (Turbo/Intercooled): 280 hp (206 kW)
Torque Ratings:
6D22 (NA): 780 Nm (575 lb-ft) @ 1,400 rpm
6D22-T2: 1,200 Nm (885 lb-ft) @ 1,400 rpm
6D22-T6: 1,050 Nm (774 lb-ft) @ 1,300 rpm
Maximum Governed Speed: 2,200-2,500 rpm (variant dependent)
Low Idle Speed: 550-650 rpm
The cylinder block is a monobloc casting manufactured from high-strength
grey cast iron with additional alloying elements for wear resistance
under sustained high loads. The block uses a deep-skirted design
extending well below the crankshaft centerline, forming a rigid ladder
frame that minimizes torsional vibration. Seven main bearing bulkheads
are cast integrally with the block, supporting a forged steel crankshaft
with induction-hardened journal surfaces. The crankcase incorporates
cast-in oil galleries on the intake side, feeding pressurized oil to the
main bearings and cylinder head.
The cylinder bores feature replaceable dry or wet-type liners depending
on the specific 6D22 variant. The liner design permits in-chassis
overhaul without removing the crankshaft on many configurations. The
block includes a timing gear housing at the front, containing the gear
train that drives the camshaft, injection pump, air compressor, power
steering pump, and other accessories. Engine mounting bosses are cast
into the block sides and flywheel housing. The water jacket surrounds
all six cylinders completely for uniform cooling.
The cylinder head is a single, cross-flow casting manufactured from
high-strength cast iron, chosen for its thermal stability under
sustained turbocharged operation. The combustion chambers are of the
direct-injection open type with a re-entrant bowl machined into the
piston crown. The cylinder head carries two valves per cylinder: one
intake and one exhaust, arranged in a straight line along the head
centerline. Valves are constructed from heat-resistant silichrome steel,
with exhaust valves featuring stellite-faced tips and hardened seats for
durability under high exhaust gas temperatures.
Valve seats are replaceable induction-hardened inserts pressed into the
cylinder head. The valvetrain operates via a camshaft located high in
the cylinder block on the right side. Mechanical lifters (solid tappets)
follow the camshaft lobes and transfer motion through hardened pushrods
to forged steel rocker arms. The rocker arms pivot on a through-shaft
mounted above the cylinder head. Valve lash adjustment uses a
screw-and-locknut arrangement at the rocker arm-to-valve stem interface.
Adjustments are performed with the engine cold. The cylinder head gasket
is a multi-layer steel (MLS) design with elastomer sealing beads.
The fuel system is a mechanical direct-injection design. An in-line
injection pump, commonly a Bosch P-type or Mitsubishi equivalent, is
mounted on the cylinder block and driven by the timing gear train. The
pump contains six individual pumping plungers, one per cylinder,
arranged in a straight line. Each plunger is actuated by a camshaft
within the pump housing.
The pump includes a mechanical centrifugal governor that maintains
engine speed under varying loads by adjusting fuel delivery. A manual
fuel shut-off lever stops the engine by cutting fuel supply. A
mechanical diaphragm-type or gear-type feed pump, mounted on the
injection pump body, draws fuel from the tank and delivers it through a
water-separating fuel filter to the injection pump.
Each cylinder has a multi-hole injector nozzle (throttle-type or
hole-type) mounted vertically in the cylinder head. Injectors are
spring-loaded, calibrated to open at a precise pressure. Standard
injection pressure is 21.6 MPa (220 kgf/cm2 / 3,130 psi). Excess fuel
not injected returns to the fuel tank through a return line for pump
cooling. The injection pump timing is set using a dial indicator and
shims, with the precise timing value varying by emission standard and
application.
The lubrication system is a forced, full-flow wet-sump design. A
gear-type oil pump is mounted internally on the front of the crankshaft
within the timing gear case. The gear pump uses a pair of meshing gears
to draw oil through a screened pickup tube from a cast aluminum or
stamped steel oil pan. Oil capacity for the engine alone is 25 to 27
liters (6.6-7.1 gal) without the filter. The full-flow spin-on oil
filter adds 4.0 to 4.5 liters (1.1-1.2 gal) for a total system capacity
of 29 to 31.5 liters (7.7-8.3 gal).
Oil passes through the pump and then through the full-flow oil filter
mounted on the cylinder block. An integral bypass valve within the
filter housing allows unfiltered oil to circulate if the filter becomes
restricted. From the filter, pressurized oil enters the main oil
gallery, a longitudinal passage drilled through the cylinder block. The
main gallery distributes oil to all seven main bearings through
cross-drilled passages.
Connecting rod bearings receive oil from the main bearings via diagonal
passages drilled through the crankshaft. A separate vertical passage in
the cylinder block carries oil to the cylinder head, where it reaches
the rocker shaft and rocker arms through hollow pushrods or external
lines. Piston cooling jets are not present on early variants; piston
cooling is managed through oil splash and the design of the piston
rings.
A water-cooled oil cooler, mounted between the block and the oil filter,
exchanges heat with the engine coolant to maintain oil temperature
within an optimal range. Oil pressure is regulated by a spring-loaded
relief valve located on the oil pump housing or within the main gallery,
which diverts excess oil back to the sump. A turbocharger oil feed line,
supplied from the main gallery, routes pressurized oil to the
turbocharger center housing on turbocharged variants. The recommended
oil grade varies by climate but generally requires diesel-rated SAE
15W-40 or SAE 20W-50, API classification CD, CE, or higher.
The cooling system is a sealed, pressurized, and thermostatically
controlled liquid-cooled design. Coolant circulation is driven by a
belt-driven centrifugal water pump mounted on the front of the cylinder
block. The water pump is driven by a multi-V serpentine belt or multiple
V-belts from the crankshaft pulley. Coolant flows from the water pump
into the cylinder block water jacket, where it circulates around the
cylinder liners and then rises through transfer passages into the
cylinder head.
The cylinder head incorporates integrated coolant passages that direct
flow around the exhaust valve seats and injector nozzles, areas of
highest thermal load. A wax-pellet thermostat is located in a housing at
the front of the cylinder head. The thermostat is rated to begin opening
at 76-82°C (169-180°F), depending on the specific application and
market. When the thermostat is closed, coolant recirculates within the
engine for rapid warm-up.
When open, coolant flows to the top tank of a down-flow radiator. A
viscous clutch or fixed-blade cooling fan is mounted on the water pump
hub. A coolant recovery reservoir connected to the radiator filler neck
captures overflow during expansion. System pressure is maintained by a
radiator cap rated for 0.7-1.0 bar (10-15 psi). On turbocharged and
intercooled variants, an air-to-air or air-to-water intercooler (charge
air cooler) reduces intake air temperature before it enters the intake
manifold.
| Intake and Exhaust Systems |
Intake System: Air enters through a heavy-duty dry-type, two-stage air
cleaner with a replaceable paper filter element and an integral dust
ejector. The air cleaner includes a restriction indicator that signals
when the element requires replacement. On turbocharged variants, clean
air flows to the turbocharger compressor inlet, then to the intercooler
(if equipped), and finally to the intake manifold which distributes
charge air evenly to all six cylinders.
Exhaust System: A single cast-iron exhaust manifold collects exhaust
gases from all six cylinders. On turbocharged variants, the manifold
routes exhaust gases into the turbocharger turbine housing. From the
turbocharger outlet, exhaust flows through a flexible coupling, an
exhaust silencer (muffler), and a vertical or horizontal exhaust stack.
Industrial and excavator variants often include a spark arrestor for
fire safety.
The engine is equipped with either a 12-volt or 24-volt negative-ground
electrical system, depending on the vehicle application. Heavy-duty
truck and construction equipment variants use 24-volt systems for higher
cranking power. The charging system uses a heavy-duty alternator with
output ranging from 35 to 70 amperes. A 24-volt or 12-volt starter
motor, rated at 5.0-7.0 kW, engages the flywheel ring gear through a
solenoid. The electrical system supplies power for the starter motor,
fuel shut-off solenoid, instrumentation, and chassis lighting.
Starting Aid: For cold weather starting, most 6D22 installations include
glow plugs (pre-heaters) mounted in the intake manifold or individual
pre-combustion chambers. Some industrial variants include an intake air
heater (grid heater) instead of glow plugs. An automatic cold start
advance system on the injection pump advances injection timing during
cranking for improved cold starting.
Turbocharger System: Turbocharged 6D22 variants are equipped with a
single, fixed-geometry turbocharger, commonly a Mitsubishi TD-series or
equivalent. The turbocharger is mounted directly on the exhaust
manifold. Exhaust gas flow spins the turbine wheel, which drives the
compressor wheel on the same shaft. The compressor draws ambient air
through the air cleaner and compresses it, increasing air density and
enabling more fuel to be burned per cycle. Water-cooled turbocharger
center housings are present on later variants for improved thermal
management.
Air Compressor (for Air Brake Equipped Vehicles): On chassis equipped
with air brakes, a single-cylinder or twin-cylinder, water-cooled air
compressor is gear-driven from the engine timing gear train. The
compressor mounts to the side of the cylinder block or timing gear
housing and supplies compressed air to the vehicle's air tank and brake
system on truck applications.
Overall Engine Length (Front Pulley to Flywheel Housing): 1,450 mm (57.1
in)
Overall Engine Width: 750 mm (29.5 in)
Overall Engine Height (From Oil Pan Rail to Valve Cover Top): 1,100 mm
(43.3 in)
Dry Weight (Base Engine, No Fluids, No Flywheel): 980 kg (2,160 lb)
Weight (With Fluids, Flywheel, Turbocharger, Starter, Alternator): 1,050
kg (2,315 lb)
Engine Oil Grade: SAE 15W-40 or SAE 20W-50 (diesel-rated, API CD, CE,
CF-4, or higher). Oil Capacity (Engine Only, No Filter): 25-27 L
(6.6-7.1 gal). Oil Filter Capacity (Spin-On, Full-Flow): 4.0-4.5 L
(1.1-1.2 gal). Total System Capacity (Engine + Filter): 29-31.5 L
(7.7-8.3 gal). Normal Oil Pressure (Rated Speed, Hot): 350-450 kPa
(51-65 psi). Minimum Oil Pressure (Hot Idle): 70-100 kPa (10-15 psi).
Engine Oil Change Interval: Change every 250 operating hours or 10,000
km (6,000 miles) for heavy-duty service, whichever occurs first. Reduce
to 150 hours for severe duty (dusty environments, frequent idling). Oil
Filter Change Interval: Replace at every oil change.
Coolant Type: Diesel-rated ethylene glycol antifreeze. Total Cooling
System Capacity (Engine and Radiator): 35-45 L (9.2-11.9 gal).
Thermostat Opening Temperature: 76-82°C (169-180°F). Radiator Cap
Pressure Rating: 0.7-1.0 bar (10-15 psi). Coolant Change Interval:
Drain, flush, and refill every 2,000 hours or every 2 years. Fuel Filter
Change Interval (Water Separator and Secondary): Replace every 500
operating hours or 20,000 km (12,000 miles).
Drain water from separator weekly in humid climates. Air Cleaner Element
Replacement: Replace primary paper element when restriction indicator
shows red or every 500 hours under normal conditions. Valve Clearance
(Cold Engine): Intake: 0.40 mm (0.016 in). Exhaust: 0.40-0.60 mm
(0.016-0.024 in) (naturally aspirated: 0.40 mm; turbocharged: 0.60 mm).
Valve Adjustment Interval: Inspect and adjust every 1,000 operating
hours or 50,000 km (31,000 miles) for truck applications.
Injection Pump Timing Check: Verify injection pump timing every 2,000
hours using a dial indicator on the pump plunger. Adjust as required.
Injector Testing: Test injector opening pressure and spray pattern every
2,000 hours. Recalibrate or replace as needed. Standard injection
pressure: 21.6 MPa (3,130 psi). Compression Test: Perform compression
test every 2,000 hours. Standard value: 2.75 MPa (398 psi) @ 250 rpm.
Service limit: 1.96 MPa (284 psi) with maximum variation between
cylinders of 0.3 MPa (3 kgf/cm2 / 43 psi).
Cylinder Head Bolts: 180 Nm (132 lb-ft).
Main Bearing Cap Bolts: 370 Nm (273 lb-ft).
Connecting Rod Cap Bolts: 115 Nm (85 lb-ft).
Flywheel Bolts (to Crankshaft Flange): 315 Nm (232 lb-ft).
Crankshaft Pulley Bolt (Front Damper): 500-550 Nm (369-406 lb-ft).
Camshaft Drive Gear Bolt: 180-200 Nm (133-148 lb-ft).
Injection Pump Mounting Nuts (to Timing Gear Housing): 40-50 Nm (30-37
lb-ft).
High-Pressure Injection Lines (Injector End, Pump End): 30-35 Nm (22-26
lb-ft).
Injector Hold-Down Clamp Bolts: 50-60 Nm (37-44 lb-ft).
Intake Manifold Bolts: 35-45 Nm (26-33 lb-ft).
Exhaust Manifold Nuts (to Cylinder Head): 50-60 Nm (37-44 lb-ft).
Turbocharger Mounting Nuts (to Exhaust Manifold): 45-55 Nm (33-41
lb-ft).
Turbocharger Oil Feed Line Fittings: 25-30 Nm (18-22 lb-ft).
Oil Pan Bolts (Cast Aluminum or Stamped Steel Pan): 20-25 Nm (15-18
lb-ft).
Valve Cover Bolts (Perimeter and Center): 10-12 Nm (7-9 lb-ft).
Thermostat Housing Bolts: 25-30 Nm (18-22 lb-ft).
Water Pump Mounting Bolts (to Cylinder Block): 35-40 Nm (26-30 lb-ft).
Oil Cooler Mounting Bolts (Water-Cooled Cooler to Block): 40-50 Nm
(30-37 lb-ft).
Starter Motor Mounting Bolts: 60-70 Nm (44-52 lb-ft).
Alternator Mounting Bracket Bolts: 45-55 Nm (33-41 lb-ft).
Air Compressor Mounting Bolts (Gear-Driven Compressor): 50-60 Nm (37-44
lb-ft).
Glow Plugs (If Equipped): 20-25 Nm (15-18 lb-ft).
Oil Drain Plug (Oil Pan): 60-70 Nm (44-52 lb-ft).
The Mitsubishi 6D22 engine was utilized as the standard or optional
diesel powertrain for the following vehicles and equipment across global
markets.
Mitsubishi Fuso Trucks:
Mitsubishi Fuso Super Great (heavy-duty truck, model year 1983-1996).
Fuso Cargo FV418 (1989-1996).
Fuso The Great FP-R (8-ton semi-tractor).
Fuso The Great U-FN428T(S6) (6D22-T6 variant).
Heavy-Duty Buses:
Mitsubishi Fuso Aerostar (large bus, select markets).
Mitsubishi Fuso Aeroqueen (intercity bus).
Construction and Excavation Equipment:
Kobelco excavators (various models, late 1980s to mid-1990s).
Kato excavators and cranes.
Caterpillar (Mitsubishi-branded) heavy equipment for Asian markets.
Industrial Power Units:
Marine diesel engines (6D22 marine variant for auxiliary power).
Stationary generator sets (prime and standby power applications).
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