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Mitsubishi K4D Engine

The Mitsubishi K4D is a vertical, water-cooled, 4-stroke, 4-cylinder inline diesel engine engineered primarily for heavy-duty industrial, agricultural, and construction machinery. It is widely integrated into equipment such as skid-steer loaders, wheel loaders, mini-excavators, and compact utility tractors.
Known for its high power-to-weight ratio and compact physical profile, the engine features an indirect injection design utilizing a swirl combustion chamber. This configuration ensures stable thermal efficiency, low operational vibration, and reliable cold-starting performance under variable industrial load profiles.

The engine features an Overhead Valve (OHV) layout driven by a gear-driven camshaft. It utilizes a total of 8 valves (2 valves per cylinder: 1 intake and 1 exhaust). Valve clearance adjustments must be performed mechanically at the rocker arm assembly according to standard service intervals. The cylinder block architecture consists of a 73 mm bore and a 78 mm stroke. This creates a total swept displacement of 1305 cc (1.305 Liters / 79.6 cubic inches).

Fuel System: Fuel delivery relies on an indirect injection (IDI) design paired with a swirl combustion chamber layout. The fuel delivery assembly features a dedicated in-line fuel injection pump assembly and mechanical throttle governor that meters fuel precisely to individual injection nozzles. A cartridge-style high-efficiency fuel filter is mounted prior to the injection pump inlet to protect precision internal tolerances from water and particulate fouling.

Lubrication System: Lubrication is managed via a forced circulation system pressurized by a high-efficiency, crankshaft-driven trochoid oil pump. The system includes a full-flow, replaceable paper element oil filter to manage particulate contamination. Oil pressure is continuously monitored through an integrated pressure switch tied into the equipment instrumentation circuit.

Cooling System: The engine employs a liquid-cooled, pressure-forced circulation system. Coolant flow is moved continuously through the block and cylinder head channels by a belt-driven centrifugal water pump. Thermal regulation is maintained via a wax-pellet type bypass thermostat that controls fluid routing between the internal engine bypass circuit and the external radiator unit.

General Technical Data

Engine Specifications

Engine Model ............... Mitsubishi K4D
Engine Type ............... 4-cycle inline 4-cylinder liquid-cooled diesel
Number of Cylinders ............... 4
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 2.87 (73.0)
Engine Stroke, in (mm) ............... 3.07 (78.0)
Displacement, cu.in (L) ............... 79.6 (1.305)
Rated Engine Power, hp (kW) ............... 21.7-28.0 (16.2-20.6)
Rated Engine Speed, rpm ............... 2400-2700
Maximum No-Load Speed, rpm ............... 2600-2900
Minimum Idle Speed, rpm ............... 800-900
Peak Torque, lb-ft (Nm) ............... 52.0-58.0 (70.5-78.6) at 1800 rpm
Aspiration Type ............... Naturally aspirated
Compression Ratio ............... 22.0:1-23.0:1
Firing Order ............... 1-3-4-2
Direction of Rotation ............... Counterclockwise viewed from flywheel side
Combustion Chamber Type ............... Swirl chamber indirect injection
Cylinder Block Material ............... Cast iron
Cylinder Head Material ............... Cast iron
Number of Valves per Cylinder ............... 2
Total Number of Valves ............... 8
Lubrication System ............... Forced pressure circulation by trochoid pump
Oil Filter Type ............... Full-flow, cartridge spin-on
Cooling System ............... Forced liquid circulation with centrifugal pump
Cooling Fan Drive ............... V-belt driven from crankshaft pulley
Air Cleaner Type ............... Dry element type
Glow Plug Type ............... Sheathed metal quick-heating elements
Starting System ............... Electric engagement motor
Electrical System, V ............... 12
Alternator Capacity, V (A) ............... 12 (35)

Fuel System

Fuel Injection Pump Model ............... Bosch-type M mini-pump
Fuel Injection Pump Type ............... In-line plunger configuration
Fuel Injection Nozzle Type ............... Throttle type nozzle pintle design
Fuel Injection Pressure, psi (bar) ............... 1706-1849 (118.0-127.5)
Fuel Injection Timing, deg ............... 18.0-20.0 BTDC
Fuel Feed Pump Mechanism ............... Diaphragm type mechanical pump
Fuel Filter Configuration ............... Spin-on element with water separator
Fuel Tank Return Line Layout ............... Overflow pipe back to secondary filter housing
Governor Type ............... Mechanical centrifugal type
Governor Spring Type ............... Dual variable speed tension spring
Plunger Outer Diameter, in (mm) ............... 0.216 (5.5)
Plunger Stroke length, in (mm) ............... 0.236 (6.0)
Delivery Valve Opening Pressure, psi (bar) ............... 426-497 (29.4-34.3)
Fuel Transfer Line Inner Diameter, in (mm) ............... 0.078 (2.0)
Fuel Transfer Line Outer Diameter, in (mm) ............... 0.236 (6.0)
Maximum Fuel System Pressure, psi (bar) ............... 2844 (196.1)
Fuel Leak-off Restrictor Hole Diameter, in (mm) ............... 0.023 (0.6)
Cold Start Enrichment Device ............... Automatic mechanical fuel enrichment rack
Fuel Shutoff Mechanism ............... Manual lever or electrical solenoid shutdown
Injection Pump Camshaft Lift, in (mm) ............... 0.236 (6.0)
Injection Pump Plunger Clearance Limit, in (mm) ............... 0.00019 (0.005)
Nozzle Needle Valve Lap Clearance, in (mm) ............... 0.00007 (0.002)
Nozzle Holder Clamping Assembly ............... Flange bolt mount to cylinder head

Dimensions and Weight

Overall Length, in (mm) ............... 22.44 (570.0)
Overall Width, in (mm) ............... 18.11 (460.0)
Overall Height, in (mm) ............... 23.62 (600.0)
Dry Weight, lbs (kg) ............... 253.5 (115.0)
Wet Weight, lbs (kg) ............... 275.5 (125.0)

Maintenance Data

Service Information

Compression Pressure (Standard), psi (bar) ............... 426 (29.4)
Compression Pressure (Minimum), psi (bar) ............... 341 (23.5)
Compression Pressure Between Cylinders, psi (bar) ............... 35.5 (2.45)
Oil Pressure at Rated RPM, psi (bar) ............... 28.4-56.8 (1.96-3.92)
Oil Pressure at Idle RPM, psi (bar) ............... 7.1-14.2 (0.49-0.98)
Radiator Cap Pressure, psi (bar) ............... 12.8 (0.88)
Thermostat Valve Opening Temperature, F (C) ............... 169-176 (76.0-80.0)
Thermostat Valve Full Open Temperature, F (C) ............... 194 (90.0)
Maximum Coolant Temperature, F (C) ............... 212 (100.0)
Minimum Coolant Temperature, F (C) ............... 140 (60.0)
Cooling Fan V-Belt Deflection, in (mm) ............... 0.39-0.47 (10.0-12.0)
Intake Valve Clearance (Cold), in (mm) ............... 0.0098 (0.25)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.0098 (0.25)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30W, SAE 10W-30, or 15W-40
API Service Classifications ......................... CD, CE, CF, CF-4
Engine Oil Capacity, High, qt (L) ............... 4.22 (4.0)
Engine Oil Capacity, Low, qt (L) ............... 2.64 (2.5)
Cooling System Capacity, qt (L) ............... 4.75 (4.5)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 100 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 400 hours
Valve clearance adjustment ............... Every 400 hours
Fuel system inspection ............... Every 600 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 800 hours
Clean radiator core ............... Every 250 hours
Inspect belt tension ............... Every 100 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 2.872 (73.00)
Cylinder Bore Out-of-Roundness, in (mm) ............... 0.00039 (0.01)
Cylinder Bore Taper Distortion, in (mm) ............... 0.00039 (0.01)
Connecting Rod Bearing Shell Thickness, in (mm) ............... 0.058 (1.49)
Connecting Rod Small End Bushing I.D, in (mm) ............... 0.827-0.828 (21.01-21.02)
Connecting Rod Big End Side Play, in (mm) ............... 0.0039-0.0098 (0.10-0.25)
Crankshaft Main Journal Outer Diameter, in (mm) ............... 1.967-1.968 (49.96-49.98)
Main Bearing Shell Thickness, in (mm) ............... 0.078 (1.99)
Main Journal Bearing Clearance, in (mm) ............... 0.0011-0.0027 (0.03-0.07)
Crankpin Journal Diameter, in (mm) ............... 1.691-1.692 (42.96-42.98)
Crankpin to Con Rod Bearing Clearance, in (mm) ............... 0.0011-0.0027 (0.03-0.07)
Crankshaft End Play, in (mm) ............... 0.0019-0.0071 (0.05-0.18)
Piston Outer Diameter, in (mm) ............... 2.871 (72.93)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0023-0.0035 (0.06-0.09)
Piston Pin Bore Inner Diameter, in (mm) ............... 0.826-0.827 (21.00-21.01)
Piston Pin Outer Diameter, in (mm) ............... 0.8265-0.8267 (20.99-21.00)
Piston Pin to Piston Bore Clearance, in (mm) ............... 0.0001-0.0003 (0.003-0.009)
Piston Pin to Con Rod Bushing Clearance, in (mm) ............... 0.0003-0.0009 (0.01-0.02)
Top Ring Groove Width, in (mm) ............... 0.079-0.081 (2.03-0.05)
Second Ring Groove Width, in (mm) ............... 0.079-0.080 (2.02-0.04)
Oil Ring Groove Width, in (mm) ............... 0.158-0.159 (4.01-4.03)
Top Ring Thickness, in (mm) ............... 0.077-0.078 (1.97-1.99)
Second Ring Thickness, in (mm) ............... 0.077-0.078 (1.97-1.99)
Oil Ring Thickness, in (mm) ............... 0.156-0.157 (3.97-3.99)
Top Ring Side Clearance, in (mm) ............... 0.0019-0.0031 (0.05-0.08)
Second Ring Side Clearance, in (mm) ............... 0.0011-0.0027 (0.03-0.07)
Oil Ring Side Clearance, in (mm) ............... 0.0007-0.0023 (0.02-0.06)
Top Ring End Gap, in (mm) ............... 0.0059-0.0118 (0.15-0.30)
Second Ring End Gap, in (mm) ............... 0.0059-0.0118 (0.15-0.30)
Oil Ring End Gap, in (mm) ............... 0.0078-0.0157 (0.20-0.40)
Cylinder Head Deck Surface Flatness, in (mm) ............... 0.0019 (0.05)
Cylinder Block Deck Surface Flatness, in (mm) ............... 0.0019 (0.05)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.258-0.259 (6.56-6.57)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.257-0.258 (6.54-6.55)
Intake Valve Guide Inner Diameter, in (mm) ............... 0.260-0.261 (6.60-6.61)
Exhaust Valve Guide Inner Diameter, in (mm) ............... 0.260-0.261 (6.60-6.61)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0011-0.0023 (0.03-0.06)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0019-0.0031 (0.05-0.08)
Valve Face Angle, deg ............... 45.0
Valve Seat Width, in (mm) ............... 0.047-0.059 (1.20-1.50)
Valve Head Thickness, in (mm) ............... 0.039 (1.0)
Valve Spring Free Length, in (mm) ............... 1.566 (39.8)
Camshaft Journal Outer Diameter (Front), in (mm) ............... 1.573-1.574 (39.96-39.98)
Camshaft Journal Outer Diameter (Center), in (mm) ............... 1.534-1.535 (38.96-38.98)
Camshaft Journal Outer Diameter (Rear), in (mm) ............... 1.494-1.495 (37.96-37.98)
Camshaft Journal Bearing Clearance, in (mm) ............... 0.0011-0.0035 (0.03-0.09)
Cam Lobe Height (Intake), in (mm) ............... 1.332 (33.84)
Cam Lobe Height (Exhaust), in (mm) ............... 1.334 (33.89)
Camshaft End Play, in (mm) ............... 0.0019-0.0059 (0.05-0.15)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.471-0.472 (11.97-11.98)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.472-0.473 (12.00-12.02)
Rocker Arm Bushing to Shaft Clearance, in (mm) ............... 0.0007-0.0019 (0.02-0.05)
Tappet Guide Bore Inner Diameter, in (mm) ............... 0.708-0.709 (18.00-18.02)
Tappet Stem Outer Diameter, in (mm) ............... 0.706-0.707 (17.95-17.97)
Tappet to Block Guide Clearance, in (mm) ............... 0.0011-0.0027 (0.03-0.07)
Idler Gear Shaft Outer Diameter, in (mm) ............... 1.180-1.181 (29.96-29.98)
Idler Gear Bushing Inner Diameter, in (mm) ............... 1.181-1.182 (30.00-30.02)
Idler Gear Bushing to Shaft Clearance, in (mm) ............... 0.0007-0.0023 (0.02-0.06)

Tightening Torques

Cylinder Head Bolt, lb-ft (Nm) ............... 54.2-57.8 (73.5-78.4)
Connecting Rod Cap Bolt, lb-ft (Nm) ............... 23.1-25.3 (31.4-34.3)
Main Bearing Cap Bolt, lb-ft (Nm) ............... 36.1-39.7 (49.0-53.9)
Flywheel Mounting Bolt, lb-ft (Nm) ............... 43.3-47.0 (58.8-63.7)
Crankshaft Center Pulley Nut, lb-ft (Nm) ............... 72.3-79.5 (98.0-107.8)
Camshaft Thrust Plate Fixing Bolt, lb-ft (Nm) ............... 7.2-8.6 (9.8-11.7)
Rocker Arm Shaft Bracket Bolt, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Valve Adjusting Locknut Stud, lb-ft (Nm) ............... 8.6-11.5 (11.7-15.6)
Cylinder Head Valve Rocker Cover Bolt, lb-ft (Nm) ............... 3.6-5.0 (4.9-6.8)
Timing Gear Case Backplate Fixing Bolt, lb-ft (Nm) ............... 13.0-15.1 (17.6-20.5)
Timing Gear Case Cover Outer Shield Bolt, lb-ft (Nm) ............... 13.0-15.1 (17.6-20.5)
Oil Pump Assembly Fastener Fixing Bolt, lb-ft (Nm) ............... 7.2-8.6 (9.8-11.7)
Oil Pan Oil Sump Peripheral Bolt, lb-ft (Nm) ............... 7.2-8.6 (9.8-11.7)
Oil Pan Bottom Drain Plug, lb-ft (Nm) ............... 25.3-32.5 (34.3-44.1)
Water Pump Housing Fixing Assembly Bolt, lb-ft (Nm) ............... 13.0-15.1 (17.6-20.5)
Thermostat Housing Assembly Bolt, lb-ft (Nm) ............... 13.0-15.1 (17.6-20.5)
Fuel Injection Pump Mounting Flange Nut, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Fuel Injection Pump Gear Drive Nut, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Fuel Injector Holder Body Nozzle Assembly, lb-ft (Nm) ............... 36.1-43.3 (49.0-58.8)
Fuel Injector Nozzle Cap Retaining Nut, lb-ft (Nm) ............... 25.3-28.9 (34.3-39.2)
Fuel High Pressure Delivery Line Nut, lb-ft (Nm) ............... 18.0-21.6 (24.5-29.4)
Fuel Low Pressure Return Pipe Banjo Bolt, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)
Glow Plug Body, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Glow Plug Wiring Harness Terminal Small Nut, lb-ft (Nm) ............... 1.0-1.5 (1.3-2.0)
Intake Manifold Flange Block Bolt, lb-ft (Nm) ............... 13.0-15.1 (17.6-20.5)
Exhaust Manifold Flange Block Bolt, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Oil Pressure Switch Sensor Unit, lb-ft (Nm) ............... 10.8-13.0 (14.7-17.6)
Coolant Temperature Sender Sensor Unit, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Starter Motor Mounting Flange Heavy Bolt, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Alternator Mounting Bracket Pivot Pivot Bolt, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Alternator Adjusting Brace Locking Clamp Bolt, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Flywheel Housing Backplate Engine Block Bolt, lb-ft (Nm) ............... 25.3-28.9 (34.3-39.2)
Front Crankshaft Oil Seal Case Fixing Bolt, lb-ft (Nm) ............... 7.2-8.6 (9.8-11.7)
Rear Crankshaft Oil Seal Fixing Bolt, lb-ft (Nm) ............... 7.2-8.6 (9.8-11.7)
Oil Pressure Relief Valve Assembly Plug, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Idler Gear Shaft Stopper Assembly Bolt, lb-ft (Nm) ............... 13.0-15.1 (17.6-20.5)
Fan Pulley Mounting Flange Small Bolt, lb-ft (Nm) ............... 7.2-8.6 (9.8-11.7)
Stop Solenoid Actuator Housing Mount Bolt, lb-ft (Nm) ............... 10.8-13.0 (14.7-17.6)
Fuel Feed Pump Mount Flange Nut, lb-ft (Nm) ............... 7.2-8.6 (9.8-11.7)
Breather Assembly Plate Top Cover Screw, lb-ft (Nm) ............... 2.1-3.6 (2.9-4.9)
Air Cleaner Mounting Bracket Support Bolt, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)

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• Mitsubishi Engines Specs
  
• Mitsubishi K4C Specs
  
• Mitsubishi K4E Specs
  
• Mitsubishi K4F Specs
  
• Mitsubishi K4M Specs
  
• Mitsubishi K4N Specs
  

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