Yanmar 4D98E Specifications
| Engine Model: Yanmar 4D98E |
| Engine Type: 4-stroke inline 4-cylinder naturally aspirated water cooled diesel |
| Total Displacement: 202.5 cu.in (3.32 L) |
| Rated Engine Power: 66 Hp (49 kW) at 2400 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 4D98E is a 3.3-liter, naturally
aspirated four-cylinder industrial diesel engine from Yanmar's
long-established D-series engine family. Introduced in the late 1990s,
this water-cooled, vertical, in-line four-cycle powerplant utilizes a
direct injection combustion system to achieve efficient fuel consumption
across a range of demanding applications.
The Yanmar 4D98E is designed as a compact, heavy-duty "workhorse" suited
for construction equipment, agricultural machinery, material handling
vehicles, marine propulsion, and power generation systems. Its robust
cast iron construction and forced lubrication system provide durability
under continuous operation in dusty, high-temperature, or
vibration-intensive environments. The engine rotates counterclockwise
when viewed from the flywheel end and employs a Bosch-type distributor
injection pump for reliable fuel delivery.
Type: Vertical, in-line, 4-cycle, water-cooled diesel engine, naturally
aspirated.
Number of Cylinders: 4.
Displacement: 3.318 L (202.5 cu.in).
Bore x Stroke: 98.0 mm (3.86 in) x 110.0 mm (4.33 in).
Compression Ratio: 18.5:1.
Combustion System: Direct injection (swirl chamber type).
Firing Order: 1-3-4-2 (cylinder No.1 located on the flywheel side).
Rotation Direction: Counterclockwise viewed from flywheel.
Rated Output: 499 kW (66 hp) at 2400 rpm.
Maximum Torque: 215.7 Nm (159.1 lb-ft) at 1700 rpm.
Rated Speed Range: 2200-2500 rpm depending on specific application
calibration.
The cylinder block is constructed from high-strength cast iron with an
inline, vertical 4-cylinder configuration. It features a robust
open-deck design where the crankcase is integrated into the block
casting, providing the structural rigidity required to withstand high
diesel cycle pressures.
The cylinder bores are machined directly into the parent cast iron
material, utilizing a plateau-honed finish to optimize piston ring
sealing and oil retention. The block incorporates five main bearing caps
to support the crankshaft. The cooling water jacket surrounds the
cylinders, providing efficient heat dissipation.
The cylinder head is a separate casting made of cast iron, designed to
house the swirl chambers, valves, and rocker arm assembly. It utilizes a
cross-flow design where intake and exhaust ports are located on opposite
sides. The engine operates 2 valves per cylinder (one intake, one
exhaust), actuated by a pushrod and rocker arm system driven by a
camshaft located in the cylinder block.
Valves: 8 total (4 intake, 4 exhaust)
Intake Valve Diameter: 34.0 mm (1.34 in)
Valve Stem Diameter: 8.0 mm (0.31 in)
Valve Seat Material: High-strength alloy steel inserts
Valve Clearance (Cold): 0.20 mm (0.008 in) for both intake and exhaust
Fuel System Type: Direct injection with distributor-type injection pump.
Injection Pump: Bosch-type VE distributor pump.
Fuel Injection Pressure: 12.3-13.3 MPa (125-135 kgf/cm2) (1780-1930
psi).
Fuel Injection Timing: 4 to 6 degrees before top dead center, adjustable
by specification class.
Applicable Fuel: Diesel oil conforming to ISO 8217 DMA or BS 2869 A1/A2.
Lubrication Type: Forced lubrication with trochoid-type oil pump.
Oil Pump Type: Trochoid pump driven from the crankshaft.
Engine Oil Capacity: 7.5 L (7.9 qt) total system capacity. Oil pan
effective capacity: 2.0 L (2.1 qt).
Recommended Oil Grade: API class CC or higher diesel engine oil.
Viscosity selection based on ambient temperature.
The lubrication system incorporates a spin-on full-flow oil filter. The
trochoid pump design provides reliable oil flow with compact dimensions
and few moving parts.
Cooling Type: Pressurized radiator cooling system with centrifugal water
pump.
Water Pump: Belt-driven centrifugal type.
Coolant Capacity: 4.2 L (4.4 qt) engine only, excluding radiator and
external piping.
The cooling system uses a radiator with fan mounted to the water pump
pulley. A thermostat regulates coolant temperature to maintain optimal
operating conditions for combustion efficiency and reduced wear.
| Intake and Exhaust Systems |
Air Intake System: Natural aspiration without turbocharger. A dry-type
replaceable air filter element removes particulates before air enters
the cylinders. The engine operates efficiently in dusty environments
when equipped with proper air filtration.
Exhaust System: Exhaust outlet positioned on the cylinder head. The
system may include a muffler for noise reduction. Marine applications
require water-cooled exhaust elbows.
Starting System: Electric start system operating on 12 volts. Starter
motor power rating ranges from 2.3 kW to 3.0 kW depending on
application.
Electrical System: 12-volt negative ground configuration. Battery
capacity: 12V-64 Ah (5-hour rating) or above. An alternator provides
charging current during operation.
Overall Engine Length: 700 mm (27.6 in) measured from fan to flywheel
face.
Overall Engine Width: 508 mm (20.0 in) measured between fuel filter and
alternator.
Overall Engine Height: 706 mm (27.8 in) measured from oil pan bottom to
rocker cover upper surface.
Dry Engine Weight: 225 kg (496 lb) without coolant, oil, or ancillary
components such as the radiator, starter motor, or alternator. The dense
cast iron construction contributes to the substantial weight, providing
vibration damping and structural rigidity.
Engine Oil Change Interval: 250 operating hours under normal conditions
using API class CC or higher oil. Severe duty operation, including dusty
environments, sustained high-load operation, or frequent cold starts,
requires 100-150 hour intervals. Oil Filter Replacement: Spin-on
cartridge replaced at every oil change. Valve Clearance Inspection
Interval: 250-500 operating hours. Adjustment as required to maintain
0.20 mm (0.008 in) clearance on both intake and exhaust valves.
Fuel Filter Replacement: Replaceable element filter. Replacement
interval of 200-300 operating hours or sooner if water contamination or
fuel flow restriction is observed. A water separator with drain
provision is incorporated. Fuel Injection Timing Check: 1000-hour
intervals. Timing marks should align when cylinder number one is at top
dead center on the compression stroke with the fuel injection pump at
the delivery point.
Injection Pressure Testing: Injectors removed and tested at 1000-hour
intervals. Opening pressure must maintain 12.3-13.3 MPa (1780-1930 psi).
Deviations exceeding 5% require injector nozzle replacement. Cooling
System Maintenance: Coolant replacement every 1000 hours or 12 months.
Radiator fins inspected and cleaned of debris at 250-hour intervals.
Water Pump Inspection: Impeller and seal inspection at 1000-hour
intervals. Bearing wear or seal leakage requires pump replacement.
Air Filter Service: Dry element cleaning every 100-150 operating hours
in normal conditions. Daily cleaning in dusty environments. Element
replacement annually or when visible damage or restriction is observed.
Cylinder Head Nut Torque Verification: 50 operating hours after cylinder
head reinstallation or engine overhaul. Retorque as specified.
Cylinder Head Nuts, Stage one: 50 Nm (36.9 lb-ft).
Cylinder Head Nuts, Stage two: 90 Nm (66.4 lb-ft).
Connecting Rod Cap Bolts: 55 Nm (40.6 lb-ft).
Main Bearing Cap Bolts: 90 Nm (66.4 lb-ft).
Flywheel Bolts: 75 Nm (55.3 lb-ft).
Injector Hold-Down Nuts: 25 Nm (18.4 lb-ft).
Rocker Arm Shaft Bracket Nuts: 22 Nm (16.2 lb-ft).
Valve Adjustment Locknuts: 18 Nm (13.3 lb-ft).
Fuel Injection Pump Mounting Nuts: 20 Nm (14.8 lb-ft).
Oil Drain Plug: 35 Nm (25.8 lb-ft).
Timing Gear Cover Bolts: 12 Nm (8.9 lb-ft).
Water Pump Mounting Bolts: 20 Nm (14.8 lb-ft).
Starter Motor Mounting Bolts: 40 Nm (29.5 lb-ft).
Alternator Mounting Bracket Bolts: 25 Nm (18.4 lb-ft).
Fan Pulley Bolts: 20 Nm (14.8 lb-ft).
The Yanmar 4D98E is installed across a wide range of industrial and
marine equipment, with the following applications documented:
Komatsu Equipment: The 4D98E is utilized in Komatsu 4D98E-1A-TR,
4D98E-1C, 4D98E-1FB, and 4D98E-1AGD-F configurations. Specific machinery
includes D21A-7T-M and D21P-7T-M tractors, FD20TH and FD30H forklifts,
PC70FR-1, PC75R-1, PC75R-2, PW75-1, and PW75R-2 excavators, SK09J-2 skid
steer loader, WA75-3 and WA85-3 wheel loaders, WB70A and WB70A-1 backhoe
loaders, and XD30 forklift.
Forklifts: Counterbalanced forklifts from 3-ton to 20-ton capacity, and
rubber-tracked forklifts from 5-ton to 25-ton capacity use this engine
as a powerplant.
Construction Equipment: Mini excavators, wheel loaders, road rollers,
dump trucks, cranes, concrete pumps, compactors, and skid steer loaders.
Agricultural Machinery: Tractors, ride-on tillers, rice transplanters,
reapers, and cultivators. The engine provides high torque at low RPM for
field operations.
Marine Applications: Fishing boats, tugboats, workboats, pleasure
crafts, passenger vessels (up to 12 meters length), and auxiliary power
for larger vessels. Marine variants incorporate corrosion-resistant
components and seawater-cooled exhaust systems.
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