Mitsubishi L3E Specifications
| Engine Model: Mitsubishi L3E |
| Engine Type: 4-cycle inline 3-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 58.1 cu.in (0.95 L) |
| Rated Engine Power: 23.7 Hp (17.7 kW) at 3600 rpm |
| Fuel System Type: Direct or indirect fuel injection |
____________________________________________________________________________________
The Mitsubishi L3E is a compact, three-cylinder
diesel engine recognized for its durable construction, operational
simplicity, and dependable performance in a wide range of light
industrial and agricultural applications. This 0.952-liter power plant
embodies a design philosophy centered on reliability, ease of
maintenance, and fuel economy. It is manufactured in multiple variants,
encompassing both traditional indirect injection (IDI) and modern direct
injection (DI) combustion systems to suit different performance and
emission requirements.
Its naturally aspirated configuration and straightforward mechanical
design contribute to a robust power curve suitable for constant-speed
and variable-load duties. The engine's compact physical envelope and
relatively low dry weight facilitate installation in space-constrained
machinery, from compact tractors to small construction equipment and
stationary generator sets.
Manufacturer: Mitsubishi Heavy Industries, Ltd. (MHI).
Engine Model: L3E.
Engine Type: 4-cycle, water-cooled, vertical inline diesel.
Combustion System: Available in Indirect Injection (Swirl Chamber) or
Direct Injection variants.
Specific model suffix denotes type (e.g., L3E-DI for Direct Injection).
Aspiration: Naturally aspirated.
Emission Compliance: Variants exist for different regional standards;
common compliance includes Japanese Industrial Standards and earlier
European directives for industrial engines.
Management System: Mechanical governing and fuel injection pump.
Number of Cylinders: 3.
Bore: 76 mm (2.992 in).
Stroke: 70 mm (2.756 in).
Displacement: 0.952 L (952 cc) (58.1 cu in).
Compression Ratio: Indirect Injection: 23:1. Direct Injection: 18:1
(varies by specific model).
Firing Order: 1-2-3.
Rotation Direction: Counter-clockwise when viewed from the flywheel
side.
Maximum Gross Power Output: 17.7 kW (23.7 hp) at 3,600 rpm for common
variants.
Output varies with governed speed, injection system, and application.
Maximum Gross Torque: 52 Nm (38 lb-ft) at 2,400 rpm (representative
value, DI variant).
Maximum Governed Speed: 3,600 rpm.
Continuous rated speeds are often lower (e.g., 3,000 or 3,300 rpm).
Idle Speed: 750-900 rpm (adjustable).
The cylinder block is a single, rigid casting from high-strength gray
iron. It is a closed-deck design, providing a robust structure for the
cylinder bores and main bearing webs. The cylinder bores are
precision-honed directly into the block material; this engine does not
use removable wet or dry liners. The crankshaft is a nodular cast iron
component, supported by four main bearings to ensure smooth operation
and minimize vibration inherent in three-cylinder layouts.
Connecting rods are forged steel, fitted with replaceable bearing shells
at the crankpin end. The small end features a pressed-fit piston pin.
Pistons are aluminum alloy. In Indirect Injection variants, pistons have
a flat or shallow dish crown. In Direct Injection variants, pistons
incorporate a specific re-entrant combustion bowl. The piston ring pack
consists of two compression rings and one oil control ring.
The cylinder head is a single-piece cast iron component. It is secured
to the block with studs and nuts. Each cylinder accommodates one intake
and one exhaust valve, positioned vertically. Valve seats are
induction-hardened for durability. The valve train is actuated by a
camshaft located in the cylinder block (OHV-Overhead Valve design). The
camshaft is gear-driven from the crankshaft.
It operates the valves via pushrods and rocker arms mounted on a shaft
on the cylinder head. Valve clearance is adjusted by means of a screw
and locknut on each rocker arm. The cylinder head design differs between
IDI and DI versions; IDI models incorporate a pre-combustion (swirl)
chamber with a glow plug, while DI models have a direct injection nozzle
mounted centrally.
The fuel system is mechanically controlled. It consists of a fuel feed
pump, a single or multi-element inline injection pump, and fuel
injectors. The injection pump is a jerk-pump type, often a Bosch VE or
similar distributor pump, driven from the engine gear train. In Indirect
Injection engines, the pump delivers fuel to pintle-type injectors that
spray into the pre-combustion chamber.
In Direct Injection engines, the pump supplies higher pressure to
multi-hole injectors that spray directly into the main combustion
chamber. Fuel delivery timing is fixed or has a mechanical advance
mechanism. A mechanical centrifugal governor, integral to the injection
pump, controls engine speed by regulating fuel rack position. A hand
priming lever is commonly fitted on the feed pump or filter housing for
system bleeding.
The engine employs a forced-feed, full-flow wet sump lubrication system.
A gear-type oil pump, driven from the crankshaft, draws oil from the
sump through a pickup strainer. Pressurized oil is fed through a
full-flow, spin-on cartridge oil filter. After filtration, oil is
directed to the main gallery, supplying the crankshaft main and
connecting rod bearings, the camshaft bearings, and the valve gear via
passages in the pushrods.
The turbocharger is not present in this naturally aspirated engine,
eliminating that oil feed requirement. The recommended engine oil is API
CD or CF grade. Total oil capacity, including the filter, is 3.5 liters
(3.7 US qt). The oil pan is a stamped steel or cast aluminum component.
Cooling is provided by a pressurized, pump-circulated liquid system. A
centrifugal water pump, driven by a V-belt from the crankshaft pulley,
circulates coolant. System temperature is regulated by a wax-pellet type
thermostat housed in the water outlet housing.
Heat is rejected via a tube-and-fin radiator; the cooling fan is mounted
on the engine and is also V-belt driven. The system requires a mixture
of ethylene-glycol antifreeze and water, usually in a 30/70 to 50/50
ratio depending on climate. Total cooling system capacity is 3.0 liters
(3.2 US qt) for the engine side, excluding the radiator.
Intake System: Comprises an air cleaner, intake manifold, and, on some
DI models, a small intake swirl port or runner design to promote air
motion. Exhaust System: Consists of an exhaust manifold and a downpipe
connecting to the machine's exhaust line. No complex after-treatment is
present on standard models.
Electrical System: Operates on a 12V system. A 12V starter motor and a
12V alternator (often 20-40A) are standard equipment. Indirect Injection
models require a glow plug system for cold starting, controlled by a key
switch or manual timer. A mechanical or electronic engine stop solenoid
acts on the injection pump fuel rack. Governor: A mechanical centrifugal
governor is integrated within the fuel injection pump.
Length (Front Face of Block to Flywheel Housing): 527 mm (20.75 in).
Width (Overall): 418 mm (16.46 in).
Height (Overall, from sump to valve cover): 532 mm (20.94 in).
Dry Weight (with standard accessories): 75 kg (165 lb).
Engine Oil Change: Every 100 to 150 operating hours. Oil Filter
Replacement: Every other oil change, or every 200-300 hours. Fuel Filter
Replacement: Every 200 to 300 operating hours. Air Cleaner Element
Service: Clean or replace based on environment; inspect every 50 hours
in dusty conditions. Valve Clearance Adjustment: Check and adjust every
500 operating hours.
Coolant Replacement: Drain, flush, and refill every 1,000 operating
hours or annually. Fan Belt Tension Check/Adjustment: Inspect and adjust
tension every 100 hours; replace at signs of wear. Fuel Injection
Pump/Injector Service: Have injection pressure and spray pattern checked
by a specialist every 1,500 hours.
Cylinder Head Nuts: Tighten in the specified crisscross pattern to 78-88
Nm (58-65 lb-ft) for final torque. Main Bearing Cap Bolts: 78-88 Nm
(58-65 lb-ft).
Connecting Rod Cap Bolts: 49-59 Nm (36-44 lb-ft).
Flywheel to Crankshaft Bolts: 78-88 Nm (58-65 lb-ft).
Fuel Injector Holder (DI type): 59-69 Nm (44-51 lb-ft).
Glow Plug (IDI type): 15-20 Nm (11-15 lb-ft).
Oil Pan Drain Plug: 39-49 Nm (29-36 lb-ft).
Oil Filter Cartridge: Hand-tighten plus 3/4 turn after gasket contact.
The Mitsubishi L3E engine is widely utilized as a prime mover in compact
machinery across multiple industries due to its size, weight, and
dependable power output. Common applications include: Compact Tractors:
Iseki TU/TX series, Satoh, and various other Japanese and Korean compact
agricultural tractors.
Construction Machinery: Komatsu PC05, PC07 mini-excavators; Mikasa plate
compactors; Morooka MST rollers. Material Handling: Komatsu and TCM
1.5-2.5 ton capacity forklifts. Generator Sets: Mobile and stationary
generators in the 10-20 kVA range. Agricultural Equipment: Irrigation
pumps, rice transplanters, small harvesters. Industrial Pumps: Various
fixed and mobile water and diaphragm pump units.
____________________________________________________________________________________
| Industrial Engines Technical Specifications |
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Outboard Engines Technical Specifications |
