Mitsubishi 4DQ5 Specifications
| Engine Model: Mitsubishi 4DQ5 |
| Engine Type: 4-cycle inline 4-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 127.2 cu.in (2.08 L) |
| Rated Engine Power: 50 Hp (37 kW) at 2800 rpm |
| Fuel System Type: Indirect injection |
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The Mitsubishi 4DQ5 is a 4-cylinder,
water-cooled, 4-stroke diesel engine from Mitsubishi’s 4DQ series. This
power unit is designed for light to medium-duty applications including
forklifts, small trucks, agricultural machinery, and marine propulsion.
The engine employs a swirl combustion system, an indirect injection
design that produces smooth operation and reduced combustion noise at
low engine speeds. The engine’s inline configuration and OHV valvetrain
provide a compact envelope for installation in constrained engine
compartments.
The Mitsubishi 4DQ5 shares its bore dimension with the 4DQ1 (1986 cc),
though the longer stroke increases displacement to 2.084 liters. A
gear-driven oil pump and a sheathed-type glow plug system enhance cold
start reliability. This engine preceded common-rail diesel technology,
utilizing a mechanical in-line injection pump serviceable with basic
tools in field conditions.
Engine Type: Inline 4-cylinder, 4-stroke, water-cooled diesel, naturally
aspirated
Displacement: 2084 cc (2.084 L / 127.2 cu.in)
Bore x Stroke: 84 mm x 94 mm (3.31 in x 3.70 in)
Compression Ratio: 21.0:1
Combustion System: Swirl combustion chamber (indirect injection, IDI)
Aspiration: Naturally aspirated (no turbocharger)
Valvetrain: OHV (Overhead Valve), 2 valves per cylinder, 8 valves total
Firing Order: 1-3-4-2
Rotation (from flywheel end): Counter-clockwise
Maximum Power (industrial): 37 kW (50 hp)
Low Idle Speed: 750-800 rpm
High Idle Speed (no-load, governed): 3000 rpm (varies by governor
setting)
Fuel Grade: No. 2D diesel fuel
Emission Standard: Euro 3 (on later production units)
The cylinder block is constructed from cast iron with an open-deck
design. Four cylinder bores are machined directly into the parent metal
without replaceable wet liners. The block incorporates a siamese bore
configuration where each cylinder shares a common wall with the adjacent
cylinder, reducing overall engine length and increasing rigidity. The
crankcase extends below the crankshaft centerline with a deep skirt
design.
Five main bearing bulkheads support the crankshaft, with thrust bearing
position at the center main journal. The water jacket surrounds the
upper portion of each cylinder bore. Cast oil galleries supply lubricant
to the main bearings and camshaft bearings. A side-mounted spin-on oil
filter threads directly onto the block casting. The cylinder block
design permits disassembly without removing the engine from the
equipment frame in many forklift applications.
Crankshaft: Forged carbon steel with five main journals. Counterweights
are integrated into the crank web. A rubber torsional vibration damper
is pressed onto the crankshaft nose. Flywheel: Cast iron with a machined
clutch surface for power take-off in industrial applications. Flywheel
housing conforms to SAE #4 or #5 pattern depending on the application.
Ring gear tooth count is 110.
The cylinder head is a single-piece cast iron component with a swirl
combustion chamber for each cylinder. Each swirl chamber is a spherical
pre-combustion chamber located off-center within the combustion bowl.
Glow plugs are threaded into each swirl chamber for cold start
assistance. The valve train is an overhead valve (OHV) configuration
with pushrods and rocker arms.
Each cylinder receives two valves: one intake and one exhaust, arranged
in a parallel valve layout. Valve stem seals are positive-type on intake
valves only. Hardened valve seat inserts on the exhaust side resist wear
under elevated temperatures. The camshaft is located in the cylinder
block, not the cylinder head. Valve clearance adjustment uses a
screw-and-locknut arrangement on the rocker arms.
The cold clearance specification for both intake and exhaust valves is
0.25 mm (0.010 in) on most 4DQ series engines. The rocker shaft is
supported by four pedestals bolted directly to the cylinder head.
Camshaft: Cast iron, located in the cylinder block on the right side.
Driven by a gear from the crankshaft. Camshaft bearings are plain-type
bronze bushings pressed into the block.
The fuel system is a mechanical indirect injection design. An in-line
injection pump, mounted to the side of the timing gear case, delivers
fuel to each cylinder in the 1-3-4-2 firing order. The injection pump
incorporates a mechanical centrifugal governor with both idle and
maximum speed control springs. A manual stop lever permits mechanical
fuel shutoff. Steel injection lines route individually to each injection
nozzle located in the swirl chamber.
Injection nozzles are throttle-type (pintle) with a specified opening
pressure range. Injection timing is adjustable by shim thickness between
the pump mounting flange and the pump base. A hand primer lever on the
feed pump permits manual bleeding of air after filter changes. A fuel
filter with an integral water sediment bowl mounts on the engine side of
the block. The system operates without electronic engine control.
The lubrication system uses a gear-driven oil pump mounted on the front
timing gear case. The pump draws oil through a wire mesh suction
strainer positioned at the bottom of the oil pan. Oil passes through a
spin-on full-flow filter mounted on the left side of the cylinder block.
A pressure relief valve in the oil pump opens at 3.0 ± 0.2 bar (43.5 ±
2.9 psi) to regulate maximum system pressure.
The system lacks piston cooling jets due to the indirect injection
combustion system generating lower thermal loads. Oil pressure at rated
speed measures 2.5-4.0 bar (36-58 psi). A low oil pressure switch
activates a warning lamp at 0.5 bar (7 psi). Standard oil pan capacity
is 5.5 L (5.8 qt) for industrial applications. The recommended engine
oil meets API Class CC or better specification.
The cooling system is pressurized and water-cooled, driven by a
belt-mounted centrifugal water pump. Coolant flows from the radiator
lower hose into the pump, then through the cylinder block water jacket,
upward through the cylinder head, and returns to the radiator top tank.
A wax-pellet thermostat, mounted in a housing on the cylinder head,
begins opening at 76.5 ± 2.0°C (169.7 ± 3.6°F) and achieves full opening
at 90°C (194°F).
A bypass circuit permits coolant circulation within the engine when the
thermostat remains closed. Coolant capacity for the engine block and
cylinder head only is 3.2 L (3.4 qt). Total system capacity, including
radiator and hoses, ranges from 5.5 to 6.5 L (5.8-6.9 qt) depending on
the installation. A removable pressure cap relieves excess pressure at
0.9-1.1 bar (13-16 psi). A four- or five-blade fan mounted to the water
pump pulley draws air through the radiator core.
Aspiration: Natural aspiration without turbocharger. Air passes through
a dry-type paper filter element with an optional foam pre-cleaner for
dusty environments.
Combustion System: Indirect injection using a swirl chamber. The chamber
volume occupies 50-55% of the total clearance volume.
Cold Start System: Four sheathed-type glow plugs, one per cylinder,
rated at 12 V. A glow controller integrates a timer relay for 5-15
second pre-heat dependent on coolant temperature. Glow plug indicator
lamp on the dashboard signals when pre-heat is active.
Electrical System: 12 V negative ground. Starter motor model M002T54172
with 2.0 kW output, pinion-shift type with overrunning clutch.
Alternator model A001T25070 with 35 A nominal output, IC regulator
maintaining 14.4 ± 0.3 V. Battery specification is 12 V, 100 Ah.
Starter Operation: Reduction gear train between armature and pinion
shaft. Armature shaft carries a drive gear meshing with a driven gear
splined to the pinion shaft. Five clutch rollers in the overrunning
clutch transmit torque in the drive direction and freewheel when the
engine overruns the starter.
Governor: Mechanical centrifugal governor integral to the injection
pump. Governor droop is 8-10% from no-load to full-load at rated speed.
Length (fan to flywheel housing): 680 mm (26.8 in)
Width (overall, exhaust manifold to injection pump): 520 mm (20.5 in)
Height (oil pan rail to rocker cover): 650 mm (25.6 in)
Dry Weight (basic engine, no flywheel, no starter, no alternator): 200
kg (441 lb)
Dry Weight (fully dressed industrial power unit): 240-260 kg (529-573
lb)
Engine Oil Change Interval: 250 hours or 6 months under normal
industrial duty.
Engine Oil Capacity (including filter): 5.5 L (5.8 qt).
Engine Oil Grade (0°C / 32°F): SAE 15W-40 or SAE 20W-50, API CC, CD, or
CF.
Engine Oil Grade (cold ambient -15°C to 0°C / 5°F to 32°F): SAE 10W-30.
Engine Oil Grade (extremely cold below -15°C / 5°F): SAE 5W-20.
Engine Oil Pressure Relief Valve Setting: 3.0 ± 0.2 bar (43.5 ± 2.9
psi).
Engine Oil Pressure at Rated Speed: 2.5-4.0 bar (36-58 psi).
Engine Oil Pressure at Low Idle (minimum, hot engine): 0.7 bar (10 psi).
Coolant Capacity (engine only): 3.2 L (3.4 qt).
Coolant Capacity (system total, including radiator): 5.5-6.5 L (5.8-6.9
qt).
Coolant Specification: Ethylene glycol base antifreeze with low-silicate
formulation.
Thermostat Opening Temperature: 76.5 ± 2.0°C (169.7 ± 3.6°F) start;
fully open at 90°C (194°F).
Fuel Filter Replacement Interval: 200 hours. Water sediment bowl drain
daily.
Air Filter Service Interval: Clean foam pre-cleaner every 50 hours.
Air Filter Service Interval: Replace paper element every 200 hours.
Valve Clearance (Cold, Intake and Exhaust): 0.25 mm (0.010 in).
Valve Clearance Inspection Interval: 250 hours.
Injection Timing (static, fuel spill method): 18-22 deg BTDC at No. 1
cylinder.
Injector Nozzle Opening Pressure: 9.8-11.8 MPa (1420-1710 psi).
Injector Nozzle Replacement Interval: 1000 hours.
Glow Plug Activation Time: 5-15 seconds dependent on coolant
temperature.
Compression Pressure (standard): 3.5-4.2 MPa (508-610 psi) at cranking
speed.
Compression Pressure Variation Between Cylinders: Maximum 0.2 MPa (29
psi) difference.
Drive Belt Tension: Deflection of 10-12 mm (0.39-0.47 in) under 10 kg
(22 lb) force at belt midpoint.
Idle Speed Adjustment (low): 750-800 rpm. Adjust via idle stop screw on
injection pump.
Idle Speed Adjustment (high, governed): 3000 rpm no-load. Adjust via max
speed screw (sealed).
Cylinder Head Bolts (Stage 1): 50 Nm (37 lb-ft)
Cylinder Head Bolts (Stage 2): 118 Nm (87 lb-ft)
Connecting Rod Cap Nuts: 54 ± 5 Nm (40 ± 4 lb-ft)
Main Bearing Cap Bolts: 83 Nm (61 lb-ft)
Flywheel Bolts (to crankshaft flange): 85 Nm (63 lb-ft)
Flywheel Housing Bolts (to block): 45 Nm (33 lb-ft)
Camshaft Thrust Plate Bolts: 20 Nm (15 lb-ft)
Rocker Arm Shaft Bracket Bolts: 35 Nm (26 lb-ft)
Rocker Arm Adjusting Lock Nut: 15 Nm (11 lb-ft)
Valve Cover Nuts (with gasket): 8 Nm (6 lb-ft)
Injection Pump Mounting Nuts (to timing case): 35 Nm (26 lb-ft)
Injection Pump Drive Gear Nut: 55 Nm (41 lb-ft)
Injection Line Fittings (pump end): 25 Nm (18 lb-ft)
Injection Line Fittings (nozzle end): 25 Nm (18 lb-ft)
Injector Hold-Down Clamp Nut: 25 Nm (18 lb-ft)
Crankshaft Pulley Bolt: 120 Nm (89 lb-ft)
Oil Pan Bolts (M8): 12 Nm (9 lb-ft)
Oil Pan Drain Plug (magnetic): 45 Nm (33 lb-ft)
Oil Filter (spin-on canister): Hand tighten plus 3/4 turn, or 15 Nm (11
lb-ft)
Water Pump Mounting Bolts: 20 Nm (15 lb-ft)
Thermostat Housing Bolts: 15 Nm (11 lb-ft)
Starter Motor Mounting Bolts (M10): 45 Nm (33 lb-ft)
Starter Motor B-terminal Nut: 10 Nm (89 lb-in)
Alternator Mounting Bolt (pivot): 35 Nm (26 lb-ft)
Alternator Adjustment Arm Bolt: 20 Nm (15 lb-ft)
Alternator B+ Terminal Nut: 8 Nm (71 lb-in)
Glow Plug (in cylinder head): 20 Nm (15 lb-ft)
Exhaust Manifold Nut: 25 Nm (18 lb-ft)
Intake Manifold Bolt: 20 Nm (15 lb-ft)
Engine Mount Bracket Bolts (to block): 60 Nm (44 lb-ft)
Forklifts: Mitsubishi FG20, FG25, FG30 series diesel forklifts.
Caterpillar (Cat) GP15, GP18, GP20 forklifts with Mitsubishi engine
packages. TCM FG20, FG25 forklifts.
Light to Medium-Duty Trucks: Mitsubishi Canter light trucks (selected
markets, replacing 4DQ1 and preceding 4DR series). Class 2 and Class 3
cab-over trucks in Asian and South American markets.
Agricultural Equipment: Mitsubishi tractors (MT series). Small combine
harvesters. Irrigation pump drives (50-80 mm suction diameter). Rice
transplanters.
Industrial Machinery: Small wheel loaders. Compact rollers and
compaction equipment. Welding generators (diesel-driven sets in the
15-25 kVA range).
Marine Applications: Sabb Motor M-Series M4.210 marine diesel (based on
4DQ5). Small workboat auxiliary power. Sailboat auxiliary propulsion up
to 40 ft length.
Commercial Mowers: Toro 450D diesel reel mowers. Other commercial turf
maintenance equipment requiring compact diesel power.
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