Mitsubishi 6D34 Specifications
| Engine Model: Mitsubishi 6D34 |
| Engine Type: 4-cycle inline 6-cylinder liquid-cooled diesel |
| Total Displacement: 358 cu.in (5.86 L) |
| Rated Engine Power: 168 Hp (125 kW) at 2150 rpm |
| Fuel System Type: Direct injection |
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The Mitsubishi 6D34 is a 5.9-liter, inline
6-cylinder diesel engine manufactured by Mitsubishi Heavy Industries.
This engine belongs to the 6D series of powerplants and represents a
highly durable and widely applied unit in commercial and industrial
sectors worldwide. Produced over several decades from the 1980s onward,
the 6D34 found extensive application in Fuso medium-duty trucks, Kobelco
and Kato hydraulic excavators, industrial generator sets, and various
construction machinery platforms.
The engine features a direct injection combustion system with an OHV
valvetrain and is available in naturally aspirated, turbocharged, and
turbocharged intercooled configurations. The Mitsubishi 6D34 gained
recognition for its robust cast iron construction, serviceability, and
capacity for high-mileage operation, making it a preferred powerplant
for construction equipment and commercial vehicles across global markets
including Japan, North America, Europe, Southeast Asia, and South
America.
The Mitsubishi 6D34 is a 4-stroke, inline 6-cylinder diesel engine
designed for medium-duty commercial trucks and heavy construction
equipment. The engine architecture follows a conventional inline
configuration with an even firing interval of 120 degrees. The bore and
stroke relationship is oversquare, with a bore of 104 mm and a stroke of
115 mm, providing a balance of low-end torque and governed speed
operation for vehicle and equipment applications.
The engine features direct injection combustion, a design that provides
better fuel efficiency compared to indirect injection predecessors. The
engine is water-cooled with a centrifugal water pump and is available in
multiple aspiration configurations depending on the specific variant and
application.
Engine Type: Inline 6-cylinder, 4-stroke diesel
Displacement: 5,861 cc (5.9 L / 358 cu.in)
Bore x Stroke: 104 mm x 115 mm (4.09 in x 4.53 in)
Compression Ratio: 16.5:1 (6D34T turbocharged)
Compression Ratio: 18.2:1 (6D34TL turbocharged intercooled)
Valvetrain: OHV, 2 valves per cylinder (12 valves total)
Firing Order: 1-5-3-6-2-4
Aspiration Options: Naturally aspirated, turbocharged, or turbocharged
with intercooler
Combustion System: Direct injection
Cooling System: Water-cooled with centrifugal pump
6D34-TL (Turbocharged Intercooled, Kato
HD820-3 / Kobelco SK235SR):
Maximum Power: 125 kW (168 hp) @ 2,150 rpm
Engine Speed Rating: 2,150 rpm governed
6D34-TLE2A (Excavator Application):
Maximum Power: 125 kW (168 hp) @ 2,150 rpm
Engine Speed Rating: 2,150 rpm governed
6D34-TL (General Industrial):
Maximum Power: 140-165 hp (104-123 kW) @ 2,500 rpm
Peak Torque Range: 440-580 Nm (325-428 lb-ft) @ 1,500-2,200 rpm
6D34-T (Turbocharged, Fuso Truck):
Maximum Power: 130-150 hp (97-112 kW) @ 2,800 rpm
Peak Torque: 400-500 Nm (295-369 lb-ft)
6D34 High-Output Variants:
Maximum Power: Up to 201 hp (150 kW) @ 2,600 rpm
Peak Torque: Up to 686 Nm (506 lb-ft) @ 1,500 rpm
Compression Pressure:
Standard Compression: 2.75 MPa (398 psi) @ 200 rpm
Minimum Compression Limit: 1.96 MPa (284 psi) @ 200 rpm
Maximum Variation Between Cylinders: 0.39 MPa (57 psi)
The cylinder block is constructed from high-strength cast iron with a
deep-skirt design that extends the cylinder walls below the crankshaft
centerline, providing rigidity required for diesel combustion pressures
in commercial applications. The block incorporates wet-type or
parent-bore cylinder construction depending on the specific production
series. The block contains seven main bearing bulkheads with reinforced
ribbing to support the forged steel crankshaft.
Cast-in water jackets surround each cylinder bore for coolant
circulation, with cooling passages directed to the upper cylinder area
where combustion temperatures are highest. The crankcase incorporates a
cast oil sump mounting flange with a gasket sealing surface. Freeze
plugs are installed in the block sides. The cylinder block also houses
the camshaft, which is driven by the timing gear train at the front of
the engine.
The cylinder head is manufactured from cast iron using an OHV (overhead
valve) design with two valves per cylinder. The valve actuation system
consists of a camshaft located in the cylinder block, mechanical lifters
(tappets), pushrods, and forged steel rocker arms mounted on a rocker
shaft. The valves are arranged in an inline configuration with intake
and exhaust valves positioned parallel to each other.
The cross-flow design places the intake manifold on one side of the
cylinder head and the exhaust manifold on the opposite side, keeping
intake air cooler and improving volumetric efficiency. Valve seats are
pressed-in alloy steel rings, and valve guides are replaceable units
pressed into the head casting. The cylinder head gasket is a composite
construction with steel fire rings around each cylinder bore.
Valves per Cylinder: 2 (1 intake, 1 exhaust)
Total Valves: 12
Valve Arrangement: Overhead valve (OHV)
Intake Valve Clearance (Cold): 0.40 mm (0.016 in)
Exhaust Valve Clearance (Cold): 0.40 mm (0.016 in)
Valve Seat Angle: 45 degrees
Camshaft Drive: Gear train
The fuel system employs a direct injection configuration with an inline
mechanical injection pump manufactured by Zexel or Bosch under license.
The injection pump is mounted on the side of the cylinder block and
driven by the engine timing gear train. The injection pump delivers fuel
to the injection nozzles at precisely timed intervals based on engine
speed and load. A mechanical governor integrated into the injection pump
housing maintains engine speed under varying operating conditions.
Each cylinder has a dedicated injection nozzle installed in the cylinder
head, directing fuel directly into the combustion chamber. The injection
timing is adjustable by rotating the injection pump mounting flange or
by adding or removing shims. A fuel filter with integral water
sedimenter is mounted on the engine or chassis frame. A hand primer
lever on the injection pump or lift pump allows manual fuel system
priming after filter changes.
Fuel Type: Diesel (standard grade, low sulfur for later variants)
Injection System: Direct injection
Injection Pump Type: Inline mechanical, with integral governor
Injection Pump Timing: Adjustable via pump mounting flange rotation
Fuel Lift Pump: Mechanical diaphragm, camshaft-driven
Turbocharger (Turbo Variants): TE06H-16M or TE06H-16M-12.0
The lubrication system is a full-pressure, forced-feed design. A
gear-type oil pump, mounted on the front of the crankshaft or within the
timing gear cover and driven directly from the crankshaft, draws oil
from the oil pan through a submerged strainer. The pump delivers oil
under pressure to a full-flow spin-on oil filter mounted on the cylinder
block. A bypass valve allows oil flow to the bearings if the filter
becomes restricted. Filtered oil is routed through a main oil gallery
machined into the cylinder block.
Cross-drilled passages direct oil from the gallery to the seven main
bearings. Drilled passages in the crankshaft feed oil from each main
bearing to the adjacent connecting rod bearings. Oil is also routed
upward through a vertical passage in the cylinder block and cylinder
head to lubricate the valve train components. An oil pressure relief
valve located near the oil pump outlet maintains system pressure. The
oil pan is constructed from stamped steel with a drain plug at its
lowest point.
Oil Type: Diesel engine oil, SAE 15W-40 or 10W-30 (API CF-4 or higher)
Total Oil Capacity (including filter): 18-22 L (4.8-5.8 US gal)
Oil Pressure (Operating, warm): 350-450 kPa (51-65 psi)
Oil Pressure (Idle, warm, minimum): 70 kPa (10 psi)
Oil Filter Type: Spin-on, full-flow
Oil Change Interval: 250-500 operating hours depending on duty cycle
The cooling system is a pressurized, forced-circulation design. A
centrifugal water pump mounted on the front of the cylinder block and
driven by a V-ribbed belt from the crankshaft pulley circulates coolant
through the engine and radiator. Coolant enters the water pump inlet, is
discharged into the cylinder block water jacket, and flows upward around
the cylinder bores and into the cylinder head. The heated coolant then
travels forward through the cylinder head to the thermostat housing
mounted at the front of the head. A wax-pellet thermostat regulates
coolant flow to the radiator, beginning to open at 76-82 °C (169-180
°F).
When closed, coolant bypasses the radiator for rapid warm-up; when open,
coolant is directed to the top tank of the radiator, passes downward
through the vertical tube-and-fin core, and returns to the water pump
inlet. A belt-driven fan mounted on the water pump hub draws air through
the radiator core. On turbocharged intercooled variants, an air-to-air
intercooler is mounted in front of the radiator. A coolant recovery tank
maintains system fill level.
Coolant Type: Ethylene glycol antifreeze with corrosion inhibitors
Total Cooling System Capacity (including radiator): 20-23 L (5.3-6.1 US
gal)
Thermostat Opening Temperature (Start): 76-82 °C (169-180 °F)
Radiator Cap Pressure: 7-10 psi (48-69 kPa)
Water Pump Type: Centrifugal, sealed bearing, belt-driven
| Intake and Exhaust Systems |
Intake System: Air enters through a dry-type paper element air cleaner
with a restriction indicator on construction equipment applications. On
turbocharged variants, compressed air from the turbocharger passes
through an intercooler (air-to-air) before entering the intake manifold.
The intake manifold is a cast iron component with a central plenum
feeding six runners.
Exhaust System: The exhaust manifold is a single-piece cast iron unit
with six ports merging into a single outlet positioned for turbocharger
mounting on turbo variants. The exhaust system includes a flexible
coupling to absorb vibration. Some variants are equipped with exhaust
gas recirculation (EGR) for emissions compliance.
The engine is equipped with a 12-volt or 24-volt electrical system
depending on the application (trucks use 12 V or 24 V; construction
equipment often uses 24 V). A belt-driven alternator produces 40-60
amperes depending on the application. A solenoid-operated starter motor
is mounted on the transmission bellhousing or engine block.
Turbocharger System: Turbocharged variants (6D34T, 6D34TL) utilize a
Mitsubishi TE06H-16M or TE06H-16M-12.0 turbocharger mounted directly to
the exhaust manifold. The turbocharger includes a wastegate to control
maximum boost pressure. Intercooled variants (6D34TL) incorporate an
air-to-air charge air cooler between the turbocharger and intake
manifold.
Governor System: A mechanical governor integrated into the injection
pump housing maintains engine speed under varying loads. The governor
includes variable speed control for vehicle applications and constant
speed settings for generator applications.
Start Aid System: Glow plugs or intake air grid heater are installed for
cold starting assistance depending on the application and ambient
temperature conditions.
The Mitsubishi 6D34 is a medium-duty engine sized for installation in
cab-over trucks and excavator engine compartments. Dimensions reflect
the inline 6-cylinder architecture with the injection pump mounted on
the side of the cylinder block.
Overall Length (timing cover to flywheel housing): 1,200 mm (47.2 in)
Overall Width (across valve cover and injection pump): 700 mm (27.6 in)
Overall Height (crankshaft centerline to top of intake manifold): 950 mm
(37.4 in)
Crankshaft Centerline to Top of Cylinder Head: 380 mm (15.0 in)
Crankshaft Centerline to Bottom of Oil Pan: 260 mm (10.2 in)
Bore Pitch: 120 mm (4.72 in)
Dry Weight (base engine, no fluids): 430-470 kg (948-1,036 lb)
Wet Weight (with all fluids): 460-500 kg (1,014-1,102 lb)
Engine Oil Change Interval: 250-500 operating hours or 6 months.
Engine Oil Filter Change Interval: Replace with every oil change.
Fuel Filter Change Interval: 250-500 operating hours or 6 months.
Valve Clearance Inspection Interval: 500 operating hours.
Valve Clearance (Cold, Intake): 0.40 mm (0.016 in).
Valve Clearance (Cold, Exhaust): 0.40 mm (0.016 in).
Compression Pressure Test: Maximum variation between cylinders 0.39 MPa.
Injection Timing Check Interval: 500-1,000 operating hours.
Injection Nozzle Inspection Interval: 1,000 operating hours.
Coolant Replacement Interval: 1,000 operating hours or 2 years.
Air Cleaner Element Cleaning/Replacement: 100-250 operating hours.
Drive Belt Inspection Interval: Inspect every 250 operating hours;
replace as needed.
Idle Speed (Warm, No Load): 600-700 rpm.
Rated Speed (Truck Applications): 2,500-2,800 rpm.
Rated Speed (Excavator Applications): 2,150 rpm.
Cylinder Head Bolts (M14): 175 Nm (129 lb-ft)
Main Bearing Bolts: 59 Nm (43.5 lb-ft)
Connecting Rod Bolts: 29 Nm (21.4 lb-ft)
Camshaft Bearing Cap Bolts: 20-25 Nm (15-18 lb-ft)
Flywheel Bolts: 78-88 Nm (58-65 lb-ft)
Intake Manifold Nuts: 20-25 Nm (15-18 lb-ft)
Exhaust Manifold Nuts (M10): 17-20 Nm (12.5-14.8 lb-ft)
Rocker Shaft Bracket Bolts: 25-30 Nm (18-22 lb-ft)
Valve Adjuster Locknuts: 16-18 Nm (12-13 lb-ft)
Oil Pan Bolts: 10-12 Nm (7-9 lb-ft)
Water Pump Mounting Bolts: 20-25 Nm (15-18 lb-ft)
Injection Pump Mounting Nuts: 20-25 Nm (15-18 lb-ft)
Injection Nozzle Retaining Nut: 50-60 Nm (37-44 lb-ft)
Turbocharger Mounting Nuts: 30-35 Nm (22-26 lb-ft)
Starter Motor Mounting Bolts: 40-45 Nm (30-33 lb-ft)
The Mitsubishi 6D34 engine is widely used across commercial truck,
construction equipment, and industrial generator platforms. Production
of the 6D34 spanned from the 1980s through the 2010s, with the final
production years from 2017 to 2021. The engine was sold under multiple
brand names including Mitsubishi Fuso, Kobelco, Kato, and various
industrial OEMs.
Mitsubishi Fuso Trucks:
Fuso Fighter (Medium-duty truck): 6D34 engine as standard powerplant for
FK and FM series.
Fuso Canter (Heavy-duty variants): Certain export market Canter models
equipped with 6D34.
Fuso Bus Chassis: Light and medium bus applications using 6D34T
turbocharged variant.
Kobelco Excavators:
SK200 Series: SK200, SK200-3, SK200-6 excavators equipped with 6D34
engine.
SK230SR, SK235SR: Medium excavators using 6D34-TL turbocharged
intercooled variant.
SK330LC: Select variants with 6D34 power.
Kato Excavators:
HD820-3: Hydraulic excavator equipped with 6D34 turbocharged intercooled
engine.
HD1430, HD1880: Select Kato excavator models.
Kawasaki Construction Equipment:
Wheel loaders: Certain Kawasaki wheel loader models equipped with 6D34
engine.
Industrial Generator Sets:
Mitsubishi Generator Series: Standby and prime power generators.
Open-skid generator sets: 60-100 kW output range using 6D34T.
Industrial Power Units:
Irrigation pumps: Stationary power units for agricultural pumping.
Compressors: Industrial air compressor drive applications.
Marine Propulsion: Small workboats and fishing vessels (select markets).
Mitsubishi Industrial Applications:
Forklifts: Heavy-duty forklift power (FD series).
Forklift variants: 6D34-MT (151 kW, 550 Nm torque).
Manufacturing period: Late 1990s-2000s.
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