________________________________________________________________________________

Mitsubishi K3M Engine

The Mitsubishi K3M is a vertical, water-cooled, 4-stroke, 3-cylinder inline diesel engine with a displacement of 1.5 liters (1,500 cc). Designed for optimal durability, energy efficiency, and compact space utilization, it is heavily relied upon in agricultural machinery and industrial applications. The engine features prominently as the primary powerplant for mini-excavators and utility tractors, such as the Mitsubishi MT300 Tractor and the Mahindra 3015. In institutional workshop settings, it is classified under the heavy-duty Mitsubishi K3 engine series and is recognized for its robust, cast-iron crankcase construction and low-vibration operation.

Valve Configuration: Overhead valve (OHV) design driven by a side-mounted camshaft via pushrods and rocker assemblies. Valves Per Cylinder: 2 valves (1 intake, 1 exhaust). Bore: 84 mm (3.307 inches). Stroke: 90 mm (3.543 inches). Total Displacement: 1500 cc (91.3 cubic inches). Lubrication System: Full forced-feed pressure lubrication system. Oil Pump: High-efficiency trochoid gear pump driven directly from the crankshaft assembly. Filtration: Full-flow, replaceable spin-on cartridge filter element. Lubricant Specification: Engine service classification API CC or CD grade oil.

Cooling System Type: Forced-circulation liquid cooling loop. Flow Activation: Centrifugal water pump driven by a V-belt connected to the crankshaft pulley. Thermal Regulation: Wax-pellet type thermostat positioned at the cylinder head water outlet to maintain optimum operational block temperatures. Air Circulation: Engine-driven cooling fan paired with a pressurized heavy-duty industrial radiator.

Fuel System: Indirect injection (IDI) or direct injection depending on the sub-variant, utilizing a dedicated pre-combustion chamber setup in standard configurations to ensure clean burning. Injection Pump: Built-in, high-pressure fuel injection pump. Timing Control: Fuel injection timing is fixed mechanically and fine-tuned via the insertion or removal of precision shims under the injection pump housing. Governing and Emissions: Integrated mechanical flyweight governor assembly fitted with built-in smoke set and Angleich torque-control devices to automatically regulate fuel delivery based on shifting engine loads.

General Technical Data

Engine Specifications

Engine Model ............... Mitsubishi K3M
Engine Type ............... 4-cycle inline 3-cylinder water-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line vertical position
Cylinder Bore, in (mm) ............... 3.307 (84.0)
Engine Stroke, in (mm) ............... 3.543 (90.0)
Total Displacement, cu.in (L) ............... 91.3 (1.496)
Rated Engine Power, hp (kW) ............... 22.0-30.0 (16.4-22.4)
Rated Engine Speed, rpm ............... 2200-2800
Maximum Idle Speed, rpm ............... 2400-3000
Minimum Idle Speed, rpm ............... 700-800
Aspiration Type ............... Naturally aspirated
Compression Ratio ............... 22.0:1
Firing Order ............... 1-3-2
Direction of Rotation ............... Counter-clockwise direction
Combustion Chamber ............... Swirl chamber
Cylinder Block Material ............... High-strength cast iron alloy
Cylinder Head Material ............... Cast iron alloy
Main Bearing Number ............... 4 precision journal insert bearings
Crankshaft Material ............... Forged steel alloy
Camshaft Material ............... Chill cast iron alloy
Valve Mechanism ............... Overhead valve config
Number of Valves Per Cylinder ............... 2 (1 intake and 1 exhaust)
Lubrication Method ............... Forced lubrication circuitry
Oil Pump Type ............... Trochoid gear pump
Oil Filter Type ............... Full-flow cartridge spin-on paper element
Cooling Method ............... Forced coolant circulation
Water Pump Type ............... Belt-driven centrifugal impeller pump
Air Cleaner Type ............... Dry heavy duty dual stage paper element
Starting System ............... Electric cranking starting motor
Electrical System ............... 12V

Fuel System

Fuel Injection Pump Type ............... Bosch M type inline multi-plunger pump
Governor Type ............... Centrifugal mechanical flyweight
Fuel Injection Nozzle Type ............... Throttle type nozzle orifice design
Fuel Injection Timing, degrees BTDC ............... 17.0-19.0
Injection Pump Feed Pressure, psi (bar) ............... 2.84-4.26 (0.20-0.30)
Nozzle Injection Starting Pressure, Std, psi (MPa) ............... 1706-1849 (11.8-12.7)
Nozzle Injection Starting Pressure, Limit, psi (MPa) ............... 1563 (10.8)
Fuel Filter Type ............... Paper element cartridge type full flow spin-on canister
Fuel Feed Pump Type ............... Mechanical diaphragm
Fuel Overflow Valve Opening Pressure, psi (MPa) ............... 21.3-28.4 (0.15-0.20)
Fuel Injection Pipe Outer Diameter, in (mm) ............... 0.236 (6.0)
Fuel Injection Pipe Inner Diameter, in (mm) ............... 0.079 (2.0)
Fuel Injection Pipe Length, in (mm) ............... 15.75 (400.0)
Fuel Return Pipe Diameter, in (mm) ............... 0.157 (4.0)
Fuel Tank Venting Pressure, psi (kPa) ............... 0.145 (1.0)
Fuel Grade Type ............... ASTM D975 No. 2-D premium grade diesel

Dimensions and Weight

Overall Length, in (mm) ............... 22.6 (575)
Overall Width, in (mm) ............... 18.9 (480)
Overall Height, in (mm) ............... 24.4 (620)
Dry Weight, lbs (kg) ............... 342 (155)

Maintenance Data

Service Information

Compression Pressure, Standard, psi (MPa) ............... 426 (2.94)
Compression Pressure, Limit, psi (MPa) ............... 370 (2.55)
Compression Pressure Between Cylinders, psi (MPa) ............... 35.5 (0.25)
Radiator Cap Relief Valve Pressure, psi (kPa) ............... 12.8 (88.3)
Thermostat Valve Crack Open Temperature, F (C) ............... 160 (71.0)
Thermostat Valve Fully Open Temperature, F (C) ............... 185 (85.0)
Fan Belt Deflection Tension, in (mm) ............... 0.39-0.47 (10.0-12.0)
Intake Valve Clearance, in (mm) ............... 0.010 (0.25)
Exhaust Valve Clearance, in (mm) ............... 0.010 (0.25)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30W, SAE 10W-30, or 15W-40
API Service Classifications ......................... CD or higher
Engine Oil Capacity, Upper Level, US qt (L) ............... 4.23 (4.0)
Engine Oil Capacity, Lower Level, US qt (L) ............... 2.96 (2.8)
Cooling System Capacity, US gal (L) ............... 1.06 (4.0)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 50 hours
Replace air cleaner ............... Every 400 hours
Replace fuel filter ............... Every 200 hours
Valve clearance adjustment ............... Every 200 hours
Fuel system inspection ............... Every 400 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 800 hours
Clean radiator core ............... Every 250 hours
Inspect belt tension ............... Every 250 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 3.307 (84.00)
Cylinder Bore Out-of-Roundness, in (mm) ............... 0.0004 (0.01)
Cylinder Bore Taper, in (mm) ............... 0.0004 (0.01)
Crankshaft Main Journal Outer Diameter, in (mm) ............... 2.2835-2.2839 (58.00-58.01)
Crankpin Journal Outer Diameter, in (mm) ............... 1.9685-1.9689 (50.00-50.01)
Crankshaft Main Bearing Oil Clearance, in (mm) ............... 0.0016-0.0035 (0.04-0.09)
Crankpin Bearing Oil Clearance, in (mm) ............... 0.0012-0.0031 (0.03-0.08)
Crankshaft End Play, in (mm) ............... 0.0020-0.0118 (0.05-0.30)
Connecting Rod Small End Bushing I.D, in (mm) ............... 1.1028-1.1035 (28.01-28.03)
Connecting Rod Big End Side Clearance, in (mm) ............... 0.0039-0.0138 (0.10-0.35)
Piston Skirt Outer Diameter, in (mm) ............... 3.304-3.305 (83.93-83.95)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0020-0.0028 (0.05-0.07)
Piston Pin Bore Inner Diameter, in (mm) ............... 1.1024-1.1028 (28.00-28.01)
Piston Pin Outer Diameter, in (mm) ............... 1.1020-1.1024 (27.99-28.00)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0001-0.0004 (0.003-0.011)
Top Ring Side Clearance, in (mm) ............... 0.0024-0.0039 (0.06-0.10)
Second Ring Side Clearance, in (mm) ............... 0.0020-0.0035 (0.05-0.09)
Oil Ring Side Clearance, in (mm) ............... 0.0012-0.0028 (0.03-0.07)
Top Ring End Gap, in (mm) ............... 0.0098-0.0157 (0.25-0.40)
Second Ring End Gap, in (mm) ............... 0.0079-0.0138 (0.20-0.35)
Oil Ring End Gap, in (mm) ............... 0.0079-0.0157 (0.20-0.40)
Cylinder Head Surface Flatness, in (mm) ............... 0.0020 (0.05)
Cylinder Block Top Surface Flatness, in (mm) ............... 0.0020 (0.05)
Valve Stem Outer Diameter (Intake), in (mm) ............... 0.3130-0.3138 (7.95-7.97)
Valve Stem Outer Diameter (Exhaust), in (mm) ............... 0.3118-0.3126 (7.92-7.94)
Valve Guide Inner Diameter Standard, in (mm) ............... 0.3150-0.3157 (8.00-8.02)
Valve Stem to Guide Clearance (Intake), in (mm) ............... 0.0012-0.0028 (0.03-0.07)
Valve Stem to Guide Clearance (Exhaust), in (mm) ............... 0.0024-0.0039 (0.06-0.10)
Valve Face Angle, degrees ............... 45.0
Valve Seat Angle, degrees ............... 45.0
Valve Spring Free Length, in (mm) ............... 1.6929 (43.0)
Camshaft Journal Outer Diameter (Front), in (mm) ............... 1.7323-1.7331 (44.00-44.02)
Camshaft Journal Outer Diameter (Center), in (mm) ............... 1.6929-1.6937 (43.00-43.02)
Camshaft Journal Outer Diameter (Rear), in (mm) ............... 1.6535-1.6543 (42.00-42.02)
Camshaft Journal Oil Clearance, in (mm) ............... 0.0020-0.0039 (0.05-0.10)
Cam Lobe Height (Intake), in (mm) ............... 1.5236 (38.70)
Cam Lobe Height (Exhaust), in (mm) ............... 1.5276 (38.80)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.4724-0.4732 (12.00-12.02)
Rocker Shaft Outer Diameter, in (mm) ............... 0.4713-0.4720 (11.97-11.99)
Rocker Arm to Shaft Clearance, in (mm) ............... 0.0004-0.0020 (0.01-0.05)

Tightening Torques

Cylinder Head M10 Bolt, lb-ft (Nm) ............... 54.2-61.5 (73.5-83.4)
Cylinder Head M12 Bolt, lb-ft (Nm) ............... 83.2-90.4 (112.8-122.6)
Connecting Rod Cap Nut, lb-ft (Nm) ............... 23.1-26.0 (31.4-35.3)
Main Bearing Cap Bolt, lb-ft (Nm) ............... 36.2-43.4 (49.0-59.0)
Flywheel Mounting Bolt, lb-ft (Nm) ............... 43.4-50.6 (59.0-68.6)
Crankshaft Pulley Center Nut, lb-ft (Nm) ............... 72.3-86.8 (98.0-117.7)
Rocker Arm Shaft Bracket Bolt, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Cylinder Head Rocker Cover Nut, lb-ft (Nm) ............... 3.6-5.1 (4.9-6.9)
Oil Pan Drain Plug, lb-ft (Nm) ............... 28.9-36.2 (39.2-49.0)
Oil Pan Mounting Bolt, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Timing Gear Case Cover Bolt, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Camshaft Thrust Plate Bolt, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Oil Pump Mounting Bolt, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Water Pump Mounting Bolt, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Thermostat Housing Bolt, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Intake Manifold Mounting Bolt, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Exhaust Manifold Mounting Nut, lb-ft (Nm) ............... 18.1-21.7 (24.5-29.4)
Starter Motor Mounting Bolt, lb-ft (Nm) ............... 28.9-36.2 (39.2-49.0)
Alternator Mounting Bracket Pivot Bolt, lb-ft (Nm) ............... 21.7-28.9 (29.4-39.2)
Glow Plug Installation, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Oil Pressure Switch, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Water Temperature Sensor, lb-ft (Nm) ............... 14.5-21.7 (19.6-29.4)

________________________________________________________________________________________

• Mitsubishi Engines Specs
  
• Mitsubishi K3E Specs
  
• Mitsubishi K3F Specs
  
• Mitsubishi K3G Specs
  
• Mitsubishi K3H Specs
  

________________________________________________________________________________

________________________________________________________________________________________

_______________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________