Yanmar 4D94E Specifications
| Engine Model: Yanmar 4D94E |
| Engine Type: 4-stroke inline 4-cylinder naturally aspirated water cooled diesel |
| Total Displacement: 186.3 cu.in (3.05 L) |
| Rated Engine Power: 55 Hp (41 kW) at 2500 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 4D94E is a 4-cylinder, naturally
aspirated industrial diesel engine from Yanmar’s 4D series, produced
from the late 1990s through the 2000s. This powerplant was engineered as
a robust, heavy-duty diesel for construction machinery, forklifts,
agricultural tractors, and power generation applications. The Yanmar
4D94E is widely recognized as the OEM engine for Komatsu FD20-30 series
forklifts, FD20T-14 forklifts, D20P-7 dozers, and WA65-3 wheel loaders.
It shares its fundamental architecture with the 4TNE94 industrial engine
and the marine 4JH series.
The engine employs a vertical inline four-cylinder configuration with a
direct injection combustion system. The 94.0 mm bore and 110.0 mm stroke
produce a displacement of 3.054 L, an under-square design that favors
low-end torque production for heavy machinery. The cast iron cylinder
block and cylinder head provide the durability required for
continuous-duty industrial applications. The forced lubrication system
uses a trochoid pump, and the pressurized radiator cooling system is
driven by a centrifugal water pump.
Power output ranges from 34 to 41 kW (45 to 55 hp) at 2,200 to 2,500 rpm
depending on the specific application and governor setting. Maximum
torque is 178 Nm (131 lb-ft) at 1,500 rpm for standard industrial
configurations. The compression ratio of 18.5:1 is calibrated for direct
injection operation. The injection pump is a Bosch-type distributor (VE)
or inline pump depending on production date, with injection pressure set
to 196-206 kg/cm2 (2,787-2,930 psi). The firing order is 1-3-4-2, with
cylinder No. 1 located on the flywheel side. Rotation is
counterclockwise when viewed from the flywheel.
Engine Type: Inline-4, vertical, water-cooled, 4-stroke, naturally
aspirated diesel
Displacement: 3.054 L (186.3 cu.in)
Bore: 94.0 mm (3.70 in)
Stroke: 110.0 mm (4.33 in)
Compression Ratio: 18.5 : 1
Firing Order: 1-3-4-2 (No. 1 cylinder on flywheel side)
Idle Speed: 600 - 650 rpm, mechanically governed
Maximum Engine Speed: 2,500 rpm governed
Rated Output: 34 - 41 kW (45 - 55 hp) @ 2,200 - 2,500 rpm
Maximum Torque: 178 Nm (131 lb-ft) @ 1,500 rpm
Fuel System: Direct injection with Bosch-type distributor or inline
injection pump
Injection Pressure: 12.3 - 13.3 MPa (1,778 - 1,920 psi)
Aspiration: Naturally aspirated
Combustion System: Direct injection with swirl chamber type combustion
chamber
Direction of Rotation: Counterclockwise (viewed from flywheel side)
Starting System: 12V Electric starter (2.0 kW or 3.0 kW)
Alternator: 12V, 15-35A depending on specification
The cylinder block is constructed from high-strength cast iron with a
heavy-duty deep-skirt design. This material choice provides exceptional
thermal stability and structural rigidity under continuous industrial
operation. The block incorporates replaceable dry-type cylinder liners.
Cylinder Liners: Replaceable liners with an inner diameter of 94.0 mm,
outer diameter of 97.5 mm, and length of 185 mm. The liner installation
requires precise interference fit and sealing.
Main bearing caps are manufactured from cast iron and are secured with
two bolts each. The main bearing structure incorporates reinforcing ribs
extending from the main bearing bulkheads to the lower crankcase area.
Crankshaft: Forged steel with five main bearings, fully
counter-weighted. The crankshaft features induction-hardened bearing
surfaces. Connecting Rods: Forged steel with machined mating surfaces.
Piston Material: Cast aluminum alloy with anodized ring grooves. Pistons
are designed for the thermal demands of direct injection combustion.
Piston Cooling: Oil splash from the connecting rod bearings provides
piston cooling; no dedicated oil jets are present in this naturally
aspirated configuration.
The cylinder head is a single-piece cast iron construction spanning all
four cylinders, chosen for its thermal stability and durability in
continuous-operation applications. The valve train operates 2 valves per
cylinder (total 8 valves) arranged in an overhead valve configuration
with pushrods and rocker arms actuated by a camshaft located in the
cylinder block.
Valvetrain: Overhead valve (OHV) with pushrods and rocker arms,
operating 2 valves per cylinder (intake and exhaust), totaling 8 valves.
The camshaft is located in the cylinder block and driven by gears from
the crankshaft.
Intake Valve Diameter: 40.0 mm (1.57 in).
Exhaust Valve Diameter: 36.0 mm (1.42 in).
Valve Clearance (cold): 0.15 - 0.25 mm (0.006 - 0.010 in) intake and
exhaust.
Valve Seat Material: High-strength sintered alloy with
induction-hardened contact surfaces.
Valve Spring Material: High-tensile steel with conventional cylindrical
design.
Camshaft Drive: Gear-driven system with steel timing gears.
The crankshaft gear drives the camshaft gear and the injection pump gear
directly.
The fuel system is a direct injection system utilizing a swirl chamber
type combustion chamber. Fuel is injected directly into the combustion
chamber via mechanical injectors.
Injection Pump: Bosch-type distributor pump (VE) or inline plunger-type
pump driven by the engine’s gear train, with individual pumping elements
for each cylinder. Fuel Injectors: Mechanical inward-opening nozzle-type
injectors mounted in the cylinder head.
Injection Timing: 4° ATDC (After Top Dead Center) for standard
industrial configurations. Fuel Filter: Spin-on type with integral water
separator. Fuel Requirement: Diesel fuel meeting ISO 8217 DMA, BS 2869
A1 or A2.
The lubrication system is a forced-feed, fully pressurized wet-sump
design with a trochoid-type oil pump. This pump design provides
consistent oil flow across the operating speed range.
Oil Pump Type: Trochoid internal gear pump driven by the camshaft gear
train. Recommended Oil Viscosity: API grade class CC or higher ; 15W-40
heavy-duty diesel engine oil for standard operating conditions.
Oil Capacity (total system): 7.5 L (7.9 qt).
Oil Capacity (oil pan effective): 2.0 L (2.1 qt).
Oil Filter Type: Spin-on full-flow filter with integral bypass valve.
Crankcase Ventilation: Open-type system with breather tube.
The cooling system is a pressurized radiator-based liquid cooling system
with a centrifugal water pump.
Water Pump Type: Centrifugal with mechanical seal, driven by the
engine’s accessory drive belt.
Coolant Type: Ethylene-glycol based antifreeze with rust inhibitors.
Coolant Capacity (engine only): 4.2 L (4.4 qt).
Thermostat: Wax-type thermostat with opening temperature of 71 - 77 °C
(160 - 170 °F).
Radiator: Cross-flow copper-brass or aluminum radiator depending on
equipment manufacturer.
Cooling Fan: Belt-driven engine fan with viscous clutch on certain
applications.
Timing Drive: Gear-driven system with steel timing gears. The crankshaft
gear drives the camshaft gear and the injection pump gear directly. This
system requires no maintenance throughout the engine’s service life.
Governor: Mechanical centrifugal governor integrated with the injection
pump, providing speed regulation under varying loads.
Starting System: 12V electric starter motor with solenoid engagement.
Exhaust System: Cast iron exhaust manifold. The exhaust system
incorporates a dry stack or spark arrestor depending on application.
Emissions Compliance: Meets emissions standards applicable at time of
manufacture (pre-Tier 3 / Euro II).
Overall Length: 700 mm (27.6 in) measured from fan to flywheel
Overall Width: 508 mm (20.0 in) measured from fuel filter to alternator
Overall Height: 706 mm (27.8 in) measured from oil pan to rocker cover
upper surface
Dry Weight (engine only): 225 kg (496 lb)
Engine Oil and Filter Change: 250 hours or 6 months for normal-duty
operation using API grade CC or higher oil; 100 hours for severe service
including dusty environments or heavy loads. Valve Clearance Inspection:
250 hours. Cold clearance specification: 0.15 - 0.25 mm (0.006 - 0.010
in) for both intake and exhaust valves. Fuel Filter Replacement: 200
hours or 12 months. Water separator draining at 50 hours or when
water-in-fuel is indicated.
Engine Air Filter Element: Clean every 50 hours; replace every 200 hours
or when restriction indicator displays service required Cooling System:
Coolant replacement every 1,000 hours or 2 years. Inspection of hoses
and belt at 250 hours. Injection Pump: No scheduled maintenance; consult
authorized service agent for timing and calibration adjustments.
Starting System: Inspect starter motor mounting bolts and electrical
connections every 500 hours.
Cylinder Head Bolts (Cast Iron Head), Step 1: 49-59 Nm (36-44 lb-ft)
Cylinder Head Bolts (Cast Iron Head), Step 2: 103-113 Nm (76-83 lb-ft)
Connecting Rod Cap Bolts: 45 Nm (33 lb-ft)
Main Bearing Cap Bolts: 70 Nm (52 lb-ft)
Flywheel Bolts: 100 Nm (74 lb-ft)
Crankshaft Pulley Nut: 150 Nm (111 lb-ft)
Injection Pump Mounting Nuts: 25 Nm (18 lb-ft)
Injection Nozzle Hold-Down Nuts: 50 Nm (37 lb-ft)
Rocker Arm Shaft Brackets: 35 Nm (26 lb-ft)
Valve Cover Nuts: 10 Nm (7 lb-ft)
Intake Manifold Nuts: 25 Nm (18 lb-ft)
Exhaust Manifold Nuts: 30 Nm (22 lb-ft)
Water Pump Mounting Bolts: 25 Nm (18 lb-ft)
Starter Motor Mounting Bolts: 40 Nm (30 lb-ft)
Alternator Mounting Bolts: 30 Nm (22 lb-ft)
Engine Mount Brackets to Block: 50 Nm (37 lb-ft)
The 4D94E engine was installed across a wide range of construction
machinery, forklifts, agricultural equipment, and power generation
applications.
Komatsu Forklifts: The 4D94E serves as the standard engine for Komatsu
FD20-14, FD20T-14, FD25-14, FD30-14, FD30T-14, FG25T-12, P60-BXD, and
500PD-14 forklift models. The engine is mounted vertically with
rear-wheel drive and is offered with standard industrial torque
converter transmission.
Komatsu Dozers and Loaders: The 4D94E powers Komatsu D20P-7, D20A-7-M,
D20P-7A-M, D20PL-7-M, D20PLL-7-M, D20Q-7-M, D20S-7-M, D21A-7-M,
D21P-7A-M, D21PL-7-M, D21Q-7-M, D21S-7-M dozers and D20S-7 loader
models.
Komatsu Wheel Loaders: The engine is installed in Komatsu WA65-3,
WA65PT-3, and WA75-3 compact wheel loaders.
Komatsu Excavators: Komatsu excavators using the 4D94E include the PC55
and PC55MR-2 models, where the engine provides the power for hydraulic
systems.
Clark Forklifts: The 4D94E powers Clark C20D, C25D, and C30D forklift
models.
Hyundai and Daewoo Excavators: The engine is installed in excavator
models including Hyundai Robex 55-3, Robex 55W, Robex 55W-3 and Daewoo
SOLAR 55V.
Agricultural Tractors: Landini TREKKER 60F tractor utilizes the Yanmar
4D94E engine. The engine is mounted longitudinally with rear-wheel drive
and standard agricultural PTO.
Power Generation: The 4D94E is used as a prime mover in diesel generator
sets, including the QAS28 generator enclosure. Industrial generator
configurations include additional cooling capacity and constant-speed
governing.
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