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Mitsubishi K4F Engine

The Mitsubishi K4F is a compact, vertical, in-line 4-cylinder four-stroke diesel engine designed primarily for agricultural, industrial, construction, and marine applications. It features a displacement of 1,490 cc (1.5 Liters). Known for its high power-to-weight ratio and durable construction, the K4F is heavily utilized in mini-excavators, wheel loaders, and small utility tractors like the Mitsubishi MT33 and Deutz Fahr Agrokid.

Valve Configuration: Overhead Valve (OHV) pushrod mechanism, driven by a gear-connected camshaft. Valves per Cylinder: 2 valves per cylinder (1 intake, 1 exhaust). Bore: 78.0 mm. Stroke: 78.0 mm. Cylinder Dimensions: Square configuration (1:1 bore-to-stroke ratio) providing a balance of low-end torque and high-rev stability.

Lubrication System: Forced pressure lubrication system. Oil Pump: Trochoid type pump driven directly via the crankshaft. Filtration: Full-flow paper filter element. Cooling System: Forced-circulation, liquid-cooled system. Components: Driven by a belt-powered centrifugal water pump alongside a heavy-duty cooling fan and standard radiator block setup.

Fuel System: Indirect Injection (IDI) using a high-efficiency swirl combustion chamber design. Compression Ratio: 23:1 for standard indirect injection builds. Fuel Injection Pump: Bosch M-Type inline mechanical multi-plunger fuel injection pump. Governor: Mechanical centrifugal flyweight type governor to control fuel delivery dynamically. Fuel Injector Nozzle: Throttle-type injection nozzle.

General Technical Data

Engine Specifications

Engine Model ............... Mitsubishi K4F
Engine Type ............... 4-cycle inline 4-cylinder indirect injection liquid-cooled diesel
Number of Cylinders ............... 4
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 3.071 (78.0)
Engine Stroke, in (mm) ............... 3.071 (78.0)
Displacement, cu.in (L) ............... 90.9 (1.490)
Rated Engine Power, hp (kW) ............... 30-33 (22.4-24.6)
Rated Engine Speed, rpm ............... 2600
Peak Torque ............... 63.4-67.8 Nm (46.8-50.0 lb-ft) at 1600-1800 rpm
Idle Speed ............... 750-850 rpm
Aspiration Type ............... Naturally Aspirated
Operating Speed ............... 2600 rpm
Compression Ratio ............... 23.0:1
Firing Order ............... 1-3-4-2
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure forced lubrication
Oil Pump Type ............... Trochoid type gear-driven pump
Oil Filter Type ............... Full-flow, spin-on cartridge
Cooling System ............... Liquid-cooled with radiator and expansion tank
Water Pump Type ............... Belt-driven centrifugal type
Air Cleaner Type ............... Dry element dual-stage type
Starting System ............... Electric starter motor
Electrical System ............... 12V
Alternator Output ............... 35A

Fuel System

Fuel Injection Pump Type ............... Bosch Type M inline mini pump
Governor Type ............... Mechanical centrifugal all-speed governor
Fuel Injection Nozzle Type ............... Throttle pintle type nozzle
Injection Timing, deg BTDC ............... 23.0
Injection Opening Pressure, psi (bar) ............... 1707-1849 (118.0-127.5)
Fuel Filter Type ............... Spin-on element paper cartridge type
Fuel Feed Pump Type ............... Mechanical diaphragm type pump
Fuel Transfer Pressure, psi (bar) ............... 2.8-4.3 (0.19-0.30)
Maximum Leak-Off Flow, gal/hr (L/hr) ............... 0.26 (1.0)
Fuel Injection Pipe Outer Diameter, in (mm) ............... 0.236 (6.0)
Fuel Injection Pipe Inner Diameter, in (mm) ............... 0.078 (2.0)

Dimensions and Weight

Overall Length, in (mm) ............... 22.4 (570)
Overall Width, in (mm) ............... 18.7 (475)
Overall Height, in (mm) ............... 23.8 (605)
Dry Weight, lbs (kg) ............... 313 (142)
Wet Weight, lbs (kg) ............... 337 (153)

Maintenance Data

Service Information

Compression Pressure, Standard, psi (bar) ............... 427 (29.4)
Compression Pressure, Limit, psi (bar) ............... 370 (25.5)
Compression Variation Between Cylinders, psi (bar) ............... 35.6 (2.45)
Oil Pressure at Rated Speed, psi (bar) ............... 42.7-71.1 (2.94-4.90)
Oil Pressure at Idle Speed, psi (bar) ............... 7.11 (0.49)
Oil Pressure Relief Valve Setting, psi (bar) ............... 56.9-71.1 (3.92-4.90)
Radiator Cap Opening Valve Pressure, psi (bar) ............... 12.8 (0.88)
Thermostat Valve Opening Temperature, F (C) ............... 169-176 (76.5-80.0)
Thermostat Valve Full Open Temperature, F (C) ............... 194 (90.0)
Fan Belt Deflection Pressed with 22 lbs, in (mm) ............... 0.39-0.59 (10.0-15.0)
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 5W-20
API Service Classifications ......................... CD or higher
Engine Oil Capacity with Filter, qt (L) ............... 5.81 (5.5)
Engine Oil Capacity, High Level, qt (L) ............... 5.28 (5.0)
Engine Oil Capacity, Low Level, qt (L) ............... 3.70 (3.5)
Coolant System Capacity, qt (L) ............... 2.64 (2.5)
Total Coolant Capacity, qt (L) ............... 6.34 (6.0)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 100 hours
Replace air cleaner ............... Every 1000 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) ............... 3.0709-3.0720 (78.000-78.030)
Cylinder Block Main Bearing Bore I.D, in (mm) ............... 2.2047-2.2055 (56.000-56.020)
Cylinder Top Surface Flatness, in (mm) ............... 0.0019 (0.05)
Cylinder Head Bottom Surface Distortion, in (mm) ............... 0.0019 (0.05)
Connecting Rod Small End Bushing I.D, in (mm) ............... 0.9061-0.9069 (23.015-23.036)
Connecting Rod Big End I.D, in (mm) ............... 1.8898-1.8906 (48.000-48.020)
Connecting Rod Side Play, in (mm) ............... 0.0039-0.0098 (0.100-0.250)
Connecting Rod Bearing Clearance, in (mm) ............... 0.0012-0.0031 (0.030-0.080)
Connecting Rod Big End Width, in (mm) ............... 0.8642-0.8661 (21.950-22.000)
Crankshaft Main Journal Outer Diameter, in (mm) ............... 2.0461-2.0469 (51.970-51.990)
Crankshaft Main Bearing Oil Clearance, in (mm) ............... 0.0014-0.0033 (0.035-0.085)
Crankpin Outer Diameter, in (mm) ............... 1.6917-1.6925 (42.970-42.990)
Crankshaft End Play, in (mm) ............... 0.0020-0.0098 (0.050-0.250)
Piston Outer Diameter, in (mm) ............... 3.0681-3.0693 (77.930-77.960)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0024-0.0035 (0.060-0.090)
Piston Pin Bore Inside Diameter, in (mm) ............... 0.9055-0.9061 (23.000-23.015)
Piston Pin Outer Diameter, in (mm) ............... 0.9052-0.9055 (22.993-23.000)
Piston Pin to Piston Bore Clearance, in (mm) ............... 0.0000-0.0009 (0.000-0.022)
Piston Pin to Small End Bushing Clearance, in (mm) ............... 0.0006-0.0017 (0.015-0.043)
Top Ring Groove Width, in (mm) ............... 0.0811-0.0827 (2.060-2.100)
Second Ring Groove Width, in (mm) ............... 0.0807-0.0819 (2.050-2.080)
Oil Ring Groove Width, in (mm) ............... 0.1583-0.1591 (4.020-4.040)
Top Ring Side Clearance, in (mm) ............... 0.0024-0.0039 (0.060-0.100)
Second Ring Side Clearance, in (mm) ............... 0.0020-0.0035 (0.050-0.090)
Oil Ring Side Clearance, in (mm) ............... 0.0008-0.0024 (0.020-0.060)
Top Ring End Gap, in (mm) ............... 0.0059-0.0138 (0.15-0.35)
Second Ring End Gap, in (mm) ............... 0.0059-0.0138 (0.15-0.35)
Oil Ring End Gap, in (mm) ............... 0.0079-0.0157 (0.20-0.40)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.2583-0.2591 (6.560-6.580)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.2571-0.2579 (6.530-6.550)
Intake Valve Guide Inner Diameter, in (mm) ............... 0.2598-0.2607 (6.600-6.622)
Exhaust Valve Guide Inner Diameter, in (mm) ............... 0.2598-0.2607 (6.600-6.622)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0008-0.0024 (0.020-0.062)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0020-0.0036 (0.050-0.092)
Valve Face Angle, deg ............... 45
Valve Seat Angle, deg ............... 45
Valve Seat Width, in (mm) ............... 0.0512-0.0709 (1.30-1.80)
Valve Spring Free Length, in (mm) ............... 1.6260 (41.30)
Camshaft Journal Outer Diameter (Front), in (mm) ............... 1.6913-1.6921 (42.960-42.980)
Camshaft Journal Outer Diameter (Center), in (mm) ............... 1.6519-1.6527 (41.960-41.980)
Camshaft Journal Outer Diameter (Rear), in (mm) ............... 1.6126-1.6134 (40.960-40.980)
Camshaft Journal Inner Diameter (Front), in (mm) ............... 1.6929-1.6945 (43.000-43.040)
Camshaft Journal Inner Diameter (Center), in (mm) ............... 1.6535-1.6551 (42.000-42.040)
Camshaft Journal Inner Diameter (Rear), in (mm) ............... 1.6142-1.6157 (41.000-41.040)
Camshaft Oil Clearance (Front), in (mm) ............... 0.0008-0.0031 (0.020-0.080)
Camshaft Oil Clearance (Center), in (mm) ............... 0.0020-0.0039 (0.050-0.100)
Camshaft Oil Clearance (Rear), in (mm) ............... 0.0008-0.0031 (0.020-0.080)
Cam Lobe Height (Intake), in (mm) ............... 1.3409 (34.06)
Cam Lobe Height (Exhaust), in (mm) ............... 1.3409 (34.06)
Camshaft End Play, in (mm) ............... 0.0020-0.0059 (0.050-0.150)
Rocker Shaft Outer Diameter, in (mm) ............... 0.4717-0.4724 (11.980-12.000)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.4728-0.4739 (12.010-12.038)
Rocker Arm Bushing to Shaft Clearance, in (mm) ............... 0.0004-0.0023 (0.010-0.058)
Idler Gear Shaft Outer Diameter, in (mm) ............... 1.3366-1.3374 (33.950-33.970)
Idler Gear Bushing Inner Diameter, in (mm) ............... 1.3386-1.3402 (34.000-34.040)
Idler Gear Bushing to Shaft Clearance, in (mm) ............... 0.0012-0.0035 (0.030-0.090)
Idler Gear End Side Play, in (mm) ............... 0.0020-0.0079 (0.050-0.200)
Crankshaft Timing Gear to Camshaft Gear Backlash, in (mm) ............... 0.0016-0.0047 (0.040-0.120)
Camshaft Gear to Injection Pump Gear Backlash, in (mm) ............... 0.0016-0.0047 (0.040-0.120)

Tightening Torques

Cylinder Head Bolts, Nm (lb-ft) ............... 73.5-83.4 (54.2-61.5)
Connecting Rod Cap Nuts, Nm (lb-ft) ............... 31.4-34.3 (23.2-25.3)
Main Bearing Cap Bolts, Nm (lb-ft) ............... 49.0-53.9 (36.1-39.8)
Flywheel Bolts, Nm (lb-ft) ............... 83.4-93.2 (61.5-68.7)
Crankshaft Pulley Center Nut, Nm (lb-ft) ............... 147.1-166.7 (108.5-122.9)
Camshaft Thrust Plate Bolt, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Camshaft Timing Gear Sprocket Bolt, Nm (lb-ft) ............... 58.8-68.6 (43.4-50.6)
Rocker Arm Shaft Bracket Bolt, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Rocker Arm Adjusting Screw Lock Nut, Nm (lb-ft) ............... 11.8-17.6 (8.7-13.0)
Cylinder Head Cover Cap Nut, Nm (lb-ft) ............... 4.9-6.9 (3.6-5.1)
Oil Pan Drain Plug, Nm (lb-ft) ............... 39.2-49.0 (28.9-36.1)
Oil Pan Mounting Bolt, Nm (lb-ft) ............... 8.8-10.8 (6.5-8.0)
Timing Gear Case Cover M6 Bolt, Nm (lb-ft) ............... 8.8-10.8 (6.5-8.0)
Timing Gear Case Cover M8 Bolt, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Fuel Injection Pump Delivery Valve Holder, Nm (lb-ft) ............... 39.2-44.1 (28.9-32.5)
Fuel Injection Pump Assembly Mounting Bolt, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Fuel Injection Pump Gear Nut, Nm (lb-ft) ............... 39.2-53.9 (28.9-39.8)
Fuel Injection Nozzle Assembly to Head, Nm (lb-ft) ............... 49.0-58.8 (36.1-43.4)
Fuel Injection Nozzle Retaining Nut, Nm (lb-ft) ............... 34.3-44.1 (25.3-32.5)
Fuel Injection High Pressure Pipe Nut, Nm (lb-ft) ............... 24.5-29.4 (18.1-21.7)
Fuel Leak-Off Pipe Nut, Nm (lb-ft) ............... 24.5-29.4 (18.1-21.7)
Glow Plug Screw, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Glow Plug Electrical Cable Connector Nut, Nm (lb-ft) ............... 1.0-1.5 (0.7-1.1)
Oil Pressure Switch Sensor, Nm (lb-ft) ............... 14.7-19.6 (10.8-14.5)
Water Temperature Sensor, Nm (lb-ft) ............... 29.4-39.2 (21.7-28.9)
Thermostat Housing Attachment Bolt, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Water Pump Assembly Mounting Bolt, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Intake Manifold Securing Bolt, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Exhaust Manifold Securing Nut, Nm (lb-ft) ............... 19.6-26.5 (14.5-19.5)
Starter Motor Mounting Bolt, Nm (lb-ft) ............... 49.0-63.7 (36.1-47.0)
Alternator Pivot Support Bolt, Nm (lb-ft) ............... 44.1-53.9 (32.5-39.8)
Alternator Adjusting Brace Lock Bolt, Nm (lb-ft) ............... 14.7-21.6 (10.8-15.9)
Flywheel Housing Mounting Bolt, Nm (lb-ft) ............... 49.0-63.7 (36.1-47.0)
Rear Oil Seal Case Retaining Bolt, Nm (lb-ft) ............... 8.8-10.8 (6.5-8.0)
Oil Pump Screen Pickup Tube Bolt, Nm (lb-ft) ............... 8.8-10.8 (6.5-8.0)
Oil Pressure Relief Valve Plug, Nm (lb-ft) ............... 39.2-49.0 (28.9-36.1)
Cooling Fan Blade Bolt, Nm (lb-ft) ............... 8.8-10.8 (6.5-8.0)
Breather Valve Body Assembly Bolt, Nm (lb-ft) ............... 4.9-6.9 (3.6-5.1)
Stop Lever Bracket Attachment Screw, Nm (lb-ft) ............... 4.9-6.9 (3.6-5.1)
Fuel Feed Pump Attachment Bolt, Nm (lb-ft) ............... 8.8-10.8 (6.5-8.0)
Front Gear Case Engine Mount Bracket Bolt, Nm (lb-ft) ............... 49.0-63.7 (36.1-47.0)
Rear Engine Mount Bracket Attachment Bolt, Nm (lb-ft) ............... 49.0-63.7 (36.1-47.0)

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• Mitsubishi Engines Specs
  
• Mitsubishi K4C Specs
  
• Mitsubishi K4D Specs
  
• Mitsubishi K4E Specs
  
• Mitsubishi K4M Specs
  
• Mitsubishi K4N Specs
  

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