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Mitsubishi K3F Engine

The Mitsubishi K3F is a vertical, water-cooled, 4-stroke, inline 3-cylinder indirect injection (IDI) diesel engine. Engineered primarily for high-demand compact applications, this engine is a prominent choice for agricultural machinery, mini excavators, and compact tractors manufactured by brands such as Airman, Deutz-Fahr, and Hitachi. The K3F is recognized for its robust power-to-weight ratio, structural compactness, and reliable fuel efficiency under varying thermal loads.

Valve Configuration: Overhead Valve (OHV) arrangement, with 2 valves per cylinder (6 valves total) arranged in-line. Rated Power: 24.0 HP (17.9 kW) depending on the specific application, governor mapping, and machinery application. Bore x Stroke: 78 mm x 78 mm. Total Displacement: 1.118 Liters (1118 cc). Compression Ratio: 23:1.

Fuel System: Swirl combustion chamber design utilizing indirect injection (IDI). Injection Pump: Bosch M-type inline multi-plunger fuel injection pump. Injection Nozzle Type: Throttle nozzle arrangement. Governor: Centrifugal flyweight type governor for stable RPM management. Injection / Firing Order: 1-3-2. Fuel Requirement: Diesel fuel oil meeting ASTM No. 2-D standards.

Lubrication System: Forced lubrication configuration. Oil Pump: High-efficiency trochoid pump. Filtration: Full-flow, replaceable paper-element oil filter cartridge. Oil Specification: API classification CD or higher. Cooling SystemType: Forced liquid/water circulation cooling system. Configuration: Utilizes an integrated belt-driven water pump, thermostat control loop, and external radiator to establish heavy-duty thermal regulation and eliminate cylinder hotspotting.

General Technical Data

Engine Specifications

Engine Model ............... Mitsubishi K3F
Engine Type ............... 4-cycle inline 3-cylinder indirect injection liquid-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line vertical
Engine Bore, mm (in) ............... 78.0 (3.071)
Engine Stroke, mm (in) ............... 78.0 (3.071)
Total Displacement, cc (cu.in) ............... 1118 (68.22)
Rated Engine Power, hp (kW) ............... 24.0 (17.9)
Rated Engine Speed, rpm ............... 3000
Max Engine Power, hp (kW) ............... 24.5 (18.3)
Maximum Torque, Nm (lb-ft) ............... 65.0 (47.9) at 2000 rpm
Low Idle Speed, rpm ............... 800-900
High Idle Speed, rpm ............... 3150-3250
Aspiration Type ............... Naturally aspirated
Compression Ratio ............... 23.0:1
Firing Order Sequence ............... 1-3-2
Combustion Chamber ............... Swirl pre-combustion chamber design
Valve Mechanism Arrangement ............... Overhead valve
Number of Valves Per Cylinder ............... 2
Cylinder Block Material ............... High-strength cast iron alloy
Cylinder Head Construction ............... Monolithic heavy duty cast iron
Lubrication System ............... Forced pressure feed loop system
Oil Pump Type ............... Gear-driven trochoid rotary pump
Oil Filter Assembly Type ............... Full-flow cartridge spin-on paper element
Cooling System ............... Liquid-cooled forced circulation circuit
Water Pump Type ............... Belt-driven centrifugal impeller pump
Air Cleaner Type ............... Heavy-duty dry dual-element type
Starting System ............... Electric starter motor engagement
Electrical System, V ............... 12
Alternator Charging, A ............... 40
Starter Motor Rating, kW (hp) ............... 1.2 (1.61)

Fuel System

Fuel Injection Pump Model ............... Bosch Type ND-PFR3M mechanical inline
Fuel Injection Pump Type ............... Bosch M type in-line mini pump unit
Fuel Injection Pump Plunder Diameter, mm (in) ............... 5.5 (0.216)
Fuel Injection Pump Stroke length, mm (in) ............... 7.0 (0.275)
Fuel Injection Nozzle Model ............... Bosch DN12SD12 throttle pintle unit
Fuel Injection Nozzle Type ............... Throttle pintle type orifice design
Fuel Injection Valve Opening Pressure, bar (psi) ............... 120.0-130.0 (1740-1885)
Fuel Injection Opening Pressure Limit, bar (psi) ............... 115.0 (1668)
Fuel Injection Timing Angle ............... 23.0 degrees BTDC
Fuel Delivery Pump Type ............... Mechanical diaphragm lift pump
Fuel Delivery Pump Pressure, bar (psi) ............... 0.2-0.3 (2.9-4.35)
Primary Fuel Filter ............... High density porous pleated paper cartridge
Water Separator ............... Transparent bowl clear sedimenter assembly
Fuel Return Line Max Backpressure, bar (psi) ............... 0.05 (0.725)
Fuel Specification Standard Class ............... ASTM Number 2-D ultra low sulfur diesel
Governor Configuration ............... Centrifugal flyweight mechanical governor
Governor Spring Free Length, mm (in) ............... 56.4 (2.220)
Governor Spring Outer Diameter, mm (in) ............... 12.8 (0.503)
Injection Nozzle Spray Pattern Angle ............... 4.0 degrees conical mist dispersion
Injection Nozzle Needle Valve Diameter, mm (in) ............... 4.0 (0.157)
Fuel Overflow Valve Crack Pressure, bar (psi) ............... 1.5 (21.7)

Dimensions and Weight

Overall Length, mm (in) ............... 530 (20.9)
Overall Width, mm (in) ............... 480 (18.9)
Overall Height, mm (in) ............... 620 (24.4)
Dry Weight, kg (lbs) ............... 98 (216)
Wet Weight, kg (lbs) ............... 104 (229)

Maintenance Data

Service Information

Cylinder Compression Pressure (Std), bar (psi) ............... 32.0 (464)
Cylinder Compression Pressure (Min), bar (psi) ............... 26.0 (377)
Engine Oil Pressure at Idle Speed, bar (psi) ............... 1.0 (14.5)
Engine Oil Pressure at Rated Speed, bar (psi) ............... 3.0 - 4.5 (43.5-65.2)
Engine Oil Pressure Relief Valve, bar (psi) ............... 5.0 (72.5)
Thermostat Valve Initial Opening Temperature, C (F) ............... 76.5 (169.7)
Thermostat Valve Full Open Heat Temperature, C (F) ............... 90.0 (194.0)
Cooling System Radiator Cap Pressure, bar (psi) ............... 0.9 (13.0)
Cooling Fan Drive Belt Deflection Tension, mm (in) ............... 10.0-12.0 (0.393-0.472)
Intake Valve Clearance, Cold, mm (in) ............... 0.25 (0.0098)
Exhaust Valve Clearance, Cold, mm (in) ............... 0.25 (0.0098)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30W, SAE 10W-30, or 5W-30
API Service Classifications ......................... CD, CE, CF-4
Engine Oil Capacity, Upper Dipstick, L (US gal) ............... 3.0 (0.79)
Engine Oil Capacity, Lower Dipstick, L (US gal) ............... 1.8 (0.48)
Engine Coolant Capacity, Engine Only, L (US gal) ............... 4.0 (1.05)
Engine Coolant Capacity with Radiator, L (US gal) ............... 6.5 (1.71)

Service Intervals

Change oil and filter ............... Every 100 hours
Inspect air cleaner ............... Every 50 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 250 hours
Valve clearance adjustment ............... Every 500 hours
Fuel system inspection ............... Every 500 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 1000 hours
Clean radiator core ............... Every 250 hours
Inspect belt tension ............... Every 250 hours

Service Specifications

Cylinder Bore Inner Diameter, mm (in) ............... 78.000-78.030 (3.0708-3.0720)
Cylinder Bore Maximum Wear Limit, mm (in) ............... 78.200 (3.0787)
Cylinder Bore Out of Roundness, mm (in) ............... 0.015 (0.0005)
Cylinder Block Top Surface Flatness Distortion, mm (in) ............... 0.05 (0.0019)
Connecting Rod Center to Center Length, mm (in) ............... 115.0 (4.527)
Connecting Rod Small End Bushing I.D, mm (in) ............... 23.015-23.025 (0.9061-0.9064)
Connecting Rod Big End Bore Inner Diameter, mm (in) ............... 46.000-46.015 (1.8110-1.8116)
Connecting Rod Bearing Oil Clearance, mm (in) ............... 0.030-0.065 (0.0011-0.0025)
Connecting Rod End Play, mm (in) ............... 0.10-0.25 (0.0039-0.0098)
Crankshaft Main Journal Width (Front), mm (in) ............... 26.0 (1.023)
Crankshaft Main Journal Width (Center), mm (in) ............... 30.0 (1.181)
Crankshaft Main Journal Width (Rear), mm (in) ............... 32.0 (1.259)
Crankshaft Main Journal Outer Diameter, mm (in) ............... 50.000-50.015 (1.9685-1.9690)
Crankshaft Main Bearing Oil Clearance, mm (in) ............... 0.035-0.072 (0.0013-0.0028)
Crankpin Journal Outer Diameter, mm (in) ............... 43.000-43.015 (1.6929-1.6935)
Crankshaft Journal Out of Roundness, mm (in) ............... 0.010 (0.0003)
Crankshaft End Play, mm (in) ............... 0.05-0.18 (0.0019-0.0070)
Main Journal Thrust Bearing Length, mm (in) ............... 30.000-30.050 (1.1811-1.1830)
Crankshaft Side Thrust Washer Thickness, mm (in) ............... 2.000-2.050 (0.0787-0.0807)
Piston Skirt Outer Diameter, mm (in) ............... 77.940-77.970 (3.0685-3.0696)
Piston to Cylinder Wall Clearance, mm (in) ............... 0.045-0.075 (0.0017-0.0029)
Piston Pin Total Length, mm (in) ............... 64.0 (2.519)
Piston Pin Bore Inner Diameter, mm (in) ............... 23.000-23.010 (0.9055-0.9059)
Piston Pin to Piston Bore Clearance, mm (in) ............... 0.002-0.012 (0.00007-0.00047)
Piston Pin to Connecting Rod Bushing Clearance, mm (in) ............... 0.015-0.031 (0.00059-0.00122)
Top Ring Groove Width, mm (in) ............... 2.030-2.050 (0.0799-0.0807)
Second Ring Groove Width, mm (in) ............... 2.020-2.040 (0.0795-0.0803)
Oil Ring Groove Width, mm (in) ............... 4.015-4.035 (0.1580-0.1588)
Top Ring Thickness, mm (in) ............... 1.970-1.995 (0.0775-0.0785)
Second Ring Thickness, mm (in) ............... 1.970-1.990 (0.0775-0.0783)
Oil Ring Thickness, mm (in) ............... 3.970-3.990 (0.1563-0.1570)
Top Ring Side Clearance, mm (in) ............... 0.050-0.075 (0.0019-0.0029)
Second Ring Side Clearance, mm (in) ............... 0.030-0.065 (0.0011-0.0025)
Oil Ring Side Clearance, mm (in) ............... 0.025-0.065 (0.0009-0.0025)
Top Ring End Gap, mm (in) ............... 0.15-0.30 (0.0059-0.0118)
Second Ring End Gap, mm (in) ............... 0.15-0.30 (0.0059-0.0118)
Oil Ring End Gap, mm (in) ............... 0.15-0.35 (0.0059-0.0137)
Cylinder Head Surface Warp Distortion Flatness, mm (in) ............... 0.05 (0.0019)
Intake Valve Stem Outer Diameter, mm (in) ............... 6.560-6.575 (0.2582-0.2588)
Exhaust Valve Stem Outer Diameter, mm (in) ............... 6.530-6.550 (0.2570-0.2578)
Valve Guide Inner Diameter, mm (in) ............... 6.600-6.615 (0.2598-0.2604)
Intake Valve Stem to Guide Clearance, mm (in) ............... 0.025-0.055 (0.0009-0.0021)
Exhaust Valve Stem to Guide Clearance, mm (in) ............... 0.050-0.085 (0.0019-0.0033)
Valve Face Angle ............... 45.0 degrees
Valve Seat Width, mm (in) ............... 1.30-1.80 (0.0511-0.0708)
Valve Head Thickness, mm (in) ............... 1.00 (0.0393)
Valve Spring Free Length, mm (in) ............... 39.50 (1.5551)
Camshaft Overall Axial Length, mm (in) ............... 385.0 (15.15)
Camshaft Journal Outer Diameter (Front), mm (in) ............... 43.000-43.025 (1.6929-1.6938)
Camshaft Journal Outer Diameter (Center), mm (in) ............... 42.000-42.025 (1.6535-1.6545)
Camshaft Journal Outer Diameter (Rear), mm (in) ............... 41.000-41.025 (1.6141-1.6151)
Camshaft Journal Oil Clearance, mm (in) ............... 0.030-0.085 (0.0011-0.0033)
Camshaft End Play, mm (in) ............... 0.05-0.22 (0.0019-0.0086)
Intake Cam Lobe Height, mm (in) ............... 33.650 (1.3248)
Exhaust Cam Lobe Height, mm (in) ............... 33.650 (1.3248)
Rocker Arm Shaft Overall Length, mm (in) ............... 365.0 (14.37)
Rocker Arm Bushing Inner Diameter, mm (in) ............... 17.000-17.020 (0.6692-0.6700)
Rocker Arm Shaft Outer Diameter, mm (in) ............... 16.965-16.985 (0.6679-0.6687)
Rocker Arm Bushing to Shaft Clearance, mm (in) ............... 0.015-0.055 (0.0005-0.0021)
Tappet Lifter Body Outer Diameter, mm (in) ............... 21.960-21.980 (0.8645-0.8653)
Tappet Lifter Guide Bore Inner Diameter, mm (in) ............... 22.000-22.025 (0.8661-0.8671)
Tappet Body to Guide Bore Clearance, mm (in) ............... 0.020-0.065 (0.0007-0.0025)

Tightening Torques

Cylinder Head Bolt, Nm (lb-ft) ............... 75.0-85.0 (55.3-62.6)
Main Bearing Cap Bolt, Nm (lb-ft) ............... 50.0-55.0 (36.8-40.5)
Connecting Rod Cap Bolt, Nm (lb-ft) ............... 32.0-35.0 (23.6-25.8)
Flywheel Mounting Flange Bolt, Nm (lb-ft) ............... 80.0-90.0 (59.0-66.3)
Crankshaft Front Pulley Center Nut, Nm (lb-ft) ............... 110.0-120.0 (81.1-88.5)
Camshaft Thrust Plate Retaining Fastener Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Rocker Arm Shaft Support Stay Fixing Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Rocker Arm Valve Clearance Adjuster Nut Jam Lock, Nm (lb-ft) ............... 12.0-18.0 (8.8-13.2)
Timing Gear Case Cover Sealing Outer Ring Bolt, Nm (lb-ft) ............... 8.0-12.0 (5.9-8.8)
Timing Gear Case Backing Rear Plate Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Main Idler Gear Shaft Mounting Foundation Bolt, Nm (lb-ft) ............... 25.0-30.0 (18.4-22.1)
Oil Sump Pan Perimeter Flange Sealing Bolt, Nm (lb-ft) ............... 8.0-12.0 (5.9-8.8)
Oil Sump Drain Outlet Hex Plug Element Core, Nm (lb-ft) ............... 40.0-50.0 (29.5-36.8)
Oil Pressure Switch Sensor Unit Tapered NPT, Nm (lb-ft) ............... 12.0-18.0 (8.8-13.2)
Oil Pump Pressure Relief Valve Internal Plug, Nm (lb-ft) ............... 35.0-45.0 (25.8-33.1)
Water Pump Assembly Base Attachment Flange Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Cooling Fan Blade Ring Plastic Hub Joining Bolt, Nm (lb-ft) ............... 8.0-12.0 (5.9-8.8)
Thermostat Housing Outlet Body Attachment Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Intake Manifold Connection Flange Engine Port Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Exhaust Manifold Connection Flange Engine Port Nut, Nm (lb-ft) ............... 20.0-25.0 (14.7-18.4)
Fuel Injection Pump Deck Mount Retention Flange Stud, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Fuel Injection Pump Drive Gear Taper Lock Attachment Nut, Nm (lb-ft) ............... 40.0-50.0 (29.5-36.8)
Fuel Injection Nozzle Holder Assembly Outer Thread In Head, Nm (lb-ft) ............... 50.0-60.0 (36.8-44.2)
Fuel Injection High Pressure Steel Line Nut, Nm (lb-ft) ............... 25.0-30.0 (18.4-22.1)
Fuel Return Spill Line Leak-Off Rail Banjo Fastener Bolt, Nm (lb-ft) ............... 20.0-25.0 (14.7-18.4)
Glow Plug Hex Body Thread Engagement Cylinder Head, Nm (lb-ft) ............... 15.0-20.0 (11.0-14.7)
Glow Plug Power Supply Rail Terminal Small Nut, Nm (lb-ft) ............... 1.5-2.0 (1.1-1.4)
Starter Motor Mounting Flange Flywheel Housing Bolt, Nm (lb-ft) ............... 45.0-55.0 (33.1-40.5)
Alternator Pivot Support Base Long Foundation Bolt, Nm (lb-ft) ............... 40.0-50.0 (29.5-36.8)
Alternator Adjusting Tension Strap Sliding Link Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Valve Cover Valve Train Top Sealing Shield Cap Nut, Nm (lb-ft) ............... 5.0-8.0 (3.6-5.9)
Air Cleaner Housing Support Bracket Frame Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Engine Suspension Front Rear Rubber Mount Bracket Bolt, Nm (lb-ft) ............... 45.0-55.0 (33.1-40.5)
Fuel Delivery Diaphragm Lift Pump Base Flange Bolt, Nm (lb-ft) ............... 15.0-22.0 (11.0-16.2)
Oil Strainer Pick Up Tube Bracket Internal Bolt, Nm (lb-ft) ............... 8.0-12.0 (5.9-8.8)
Crankshaft Rear Oil Seal Retainer Back Case Bolt, Nm (lb-ft) ............... 8.0-12.0 (5.9-8.8)
Flywheel Housing Shell Structural Engine Block Bolt, Nm (lb-ft) ............... 45.0-55.0 (33.1-40.5)
Exhaust Pipe Connection Downpipe Flange Coupling Nut, Nm (lb-ft) ............... 30.0-40.0 (22.1-29.5)
Water Temperature Sender Unit Sensor Port Brass Nut, Nm (lb-ft) ............... 20.0-30.0 (14.7-22.1)
Fuel Filter Bracket Structural Mount Chassis Frame Bolt, Nm (lb-ft) ............... 20.0-30.0 (14.7-22.1)
Injection Pump Delivery Valve Holder Internal Hex Nut, Nm (lb-ft) ............... 35.0-40.0 (25.8-29.5)
Injection Pump Control Rack Alignment Guide Screw, Nm (lb-ft) ............... 6.0-9.0 (4.4-6.6)
Governor Housing Cover Plate Assembly Rear Screw, Nm (lb-ft) ............... 6.0-8.0 (4.4-5.9)
Breather Valve Air Baffle Plate Cover Top Bolt, Nm (lb-ft) ............... 8.0-12.0 (5.9-8.8)

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• Mitsubishi Engines Specs
  
• Mitsubishi K3E Specs
  
• Mitsubishi K3G Specs
  
• Mitsubishi K3H Specs
  
• Mitsubishi K3M Specs
  

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