________________________________________________________________________________

Mitsubishi K3C Engine

The Mitsubishi K3C is a vertical, inline, 3-cylinder, 4-stroke, water-cooled industrial diesel engine with a displacement of 0.900 liters (900 cc). Celebrated for its power-to-weight ratio and highly compact footprint, this engine is widely utilized globally to power agricultural and construction machinery. It serves as the primary powerplant for sub-compact utility tractors, including the Iseki TU150, TU157, TU160, and TU1600 series, as well as VST MT180 and MT224 tractors. Designed for continuous heavy-duty cycles, the engine utilizes a heavy-cast iron cylinder block and head assembly to withstand high mechanical loads.

The cylinder head utilizes an Overhead Valve (OHV) arrangement with two valves per cylinder, equating to a total of 6 valves (3 intake, 3 exhaust) across the entire engine block. The valvetrain operates mechanically via a camshaft-driven assembly transferring lift to the rocker gear through cylindrical valve lifter tapets and pushrods. Cylinder Bore: 70.00 mm (2.75 in). Piston Stroke: 78.00 mm (3.07 in). Total Engine Displacement: 900 cc (54.9 cubic inches). Compression Ratio: 23:1.

Fuel System: The K3C relies on a high-efficiency indirect injection layout featuring a swirl combustion chamber design. Injection Pump Type: Bosch "M" type in-line multi-plunger fuel injection pump. Injection Nozzles: High-speed diesel pintle-type throttle nozzles designed to optimize fuel vaporization inside the swirl chamber pre-combustion zones. Speed Regulation: A mechanical centrifugal flyweight governor directly monitors the pump rack to keep fuel mapping consistent under shifting mechanical loads. Cold Starting Aid: 12-volt quick-heating glow plugs located in each swirl chamber entry path.

The engine employs a full forced-feed lubrication system driven by an internal trochoid-type oil pump. Pressurized engine oil is forced through a spin-on paper cartridge element filter before distributing down the main oil galleries to supply the crankshaft bearings, connecting rod journals, and overhead rocker assemblies. Pressure Control: Integrated oil pressure switch monitoring minimum safe operational limits. Thermal regulation is handled through a liquid-cooled configuration using a pressurized radiator and a closed bypass loop. Coolant circulation is forced actively across the cylinder sleeves and head passages via a front-mounted, belt-driven centrifugal water pump working alongside a high-flow cooling fan.

General Technical Data

Engine Specifications

Engine Model ............... Mitsubishi K3C
Engine Type ............... 4-cycle water-cooled vertical inline diesel engine
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 2.756 (70.0)
Engine Stroke, in (mm) ............... 3.071 (78.0)
Displacement, cu.in (L) ............... 54.96 (0.900)
Rated Engine Power, hp (kW) ............... 18.5 (13.8)
Rated Engine Speed, rpm ............... 2700
Peak Torque ............... 51.9 Nm (38.3 lb-ft)
Peak Torque Speed, rpm ............... 1600-1900
Idle Speed, rpm ............... 800-900
Max No-Load Speed, rpm ............... 2900-3000
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 23:1
Firing Order ............... 1-3-2
Combustion Chamber ............... Swirl Chamber (Indirect Injection)
Cylinder Block Type ............... Cast iron unlined mono-block
Cylinder Head Type ............... Cast iron cross-flow single-piece OHV design
Lubrication System ............... Forced pressure feed system
Oil Pump Type ............... Trochoid type gear-driven assembly
Oil Filter Type ............... Full-flow paper element spin-on canister style
Cooling System ............... Liquid cooled forced circulation setup
Water Pump Type ............... Belt-driven centrifugal impeller layout
Cooling Fan Blades ............... 4-blade high-flow push/pull layout
Air Cleaner Type ............... Dry dual-stage element housing assembly
Starting System ............... Electric starter motor assembly
Glow Plug Type ............... 12V quick-heat sheathed metal elements
Electrical System ............... 12V positive
Alternator Output ............... 15A or 35A

Fuel System

Fuel Injection Pump Type ............... Bosch M type in-line mini plug-in pump assembly
Fuel Injection Pump Feed ............... Gravity or mechanical diaphragm lift pump layout
Injection Pump Drive Line ............... Gear driven off the main camshaft assembly
Fuel Injection Nozzle Type ............... Throttle pintle type orifice design assembly
Injection Start Pressure Standard, psi (MPa) ............... 1706-1849 (11.77-12.75)
Injection Start Pressure Repair Limit, psi (MPa) ............... 1564 (10.79)
Injection Timing Standard Angle ............... 21-23 degrees BTDC
Governor Mechanism Type ............... Centrifugal flyweight mechanical regulation system
Fuel Specification Standard ............... ASTM D975 No. 2-D or JIS K2204 Class 2
Low Temperature Fuel Specs ............... ASTM D975 No.1-D or JIS K2204 Class 3
Fuel Filter Medium ............... High density micro-porous replaceable paper element
Fuel Feed Lift Pump Pressure, psi (MPa) ............... 2.84-4.26 (0.019-0.029)
Injection Pipe Outer Diameter, in (mm) ............... 0.236 (6.0)
Injection Pipe Inner Diameter, in (mm) ............... 0.078 (2.0)
Nozzle Holder Assembly Type ............... Screw-in body thread mounting assembly
Overflow Pipe Return System ............... Banjo joint connection to main fuel line circuit reservoir

Dimensions and Weight

Overall Length, in (mm) ............... 19.9 (505)
Overall Width, in (mm) ............... 17.5 (445)
Overall Height, in (mm) ............... 21.6 (550)
Dry Weight, lbs (kg) ............... 276 (125)

Maintenance Data

Service Information

Compression Pressure (Standard), psi (MPa) ............... 426 (2.94)
Compression Pressure (Minimum), psi (MPa) ............... 355 (2.45)
Compression Between Cylinders (Maximum), psi (MPa) ............... 35.5 (0.245)
Oil Pressure at Idle Speed, psi (MPa) ............... 14.2 (0.098)
Oil Pressure at Rated Speed, psi (MPa) ............... 42.6-71.1 (0.294-0.490)
Relief Valve Cracking Pressure, psi (MPa) ............... 56.8-62.5 (0.392-0.431)
Thermostat Valve Opening Temperature, F (C) ............... 170.6 (77.0)
Thermostat Valve Full Open Temperature, F (C) ............... 194.0 (90.0)
Radiator Cap Pressure, psi (MPa) ............... 12.8 (0.088)
Fan Belt Deflection, in (mm) ............... 0.39-0.47 (10.0-12.0)
Intake Valve Clearance, in (mm) ............... 0.0098 (0.25)
Exhaust Valve Clearance, in (mm) ............... 0.0098 (0.25)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30W, SAE 10W-30, or 5W-30
API Service Classifications ......................... CC, CD, or CE
Engine Oil Capacity, High Limit, qt (L) ............... 3.17 (3.0)
Engine Oil Capacity, Low Limit, qt (L) ............... 1.90 (1.8)
Engine Oil Capacity with Filter, qt (L) ............... 3.38 (3.2)
Cooling System Capacity, qt (L) ............... 4.22 (4.0)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 50 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 200 hours
Valve clearance adjustment ............... Every 400 hours
Fuel system inspection ............... Every 1000 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 Inner Diameter, in (mm) ............... 2.7559-2.7567 (70.000-70.020)
Cylinder Bore Maximum, Wear Limit, in (mm) ............... 2.7638 (70.20)
Crankshaft Main Journal Outer Diameter, in (mm) ............... 1.9665-1.9671 (49.950-49.965)
Crankpin Outer Diameter, in (mm) ............... 1.5730-1.5736 (39.955-39.970)
Main Bearing to Journal Oil Clearance, in (mm) ............... 0.0013-0.0033 (0.035-0.085)
Crankpin Bearing to Journal Oil Clearance, in (mm) ............... 0.0011-0.0030 (0.030-0.078)
Crankshaft End Play, in (mm) ............... 0.0019-0.0070 (0.05-0.18)
Connecting Rod Big End Side Play, in (mm) ............... 0.0039-0.0137 (0.10-0.35)
Main Bearing Shell Thickness, in (mm) ............... 0.0787 (2.000)
Connecting Rod Bearing Shell Thickness, in (mm) ............... 0.0590 (1.500)
Piston Outer Diameter, in (mm) ............... 2.7535-2.7543 (69.940-69.960)
Piston to Cylinder Bore Clearance, in (mm) ............... 0.0019-0.0031 (0.050-0.080)
Piston Pin Bushing Inner Diameter, in (mm) ............... 0.7874-0.7881 (20.001-20.019)
Piston Pin Outer Diameter, in (mm) ............... 0.7871-0.7874 (19.993-20.000)
Piston Pin to Piston Boss Bore Clearance, in (mm) ............... 0.0000-0.0004 (0.000-0.011)
Piston Pin to Connecting Rod Small End Clearance, in (mm) ............... 0.0001-0.0010 (0.003-0.026)
Top Ring Side Clearance, in (mm) ............... 0.0023-0.0037 (0.060-0.095)
Second Ring Side Clearance, in (mm) ............... 0.0019-0.0033 (0.050-0.085)
Oil Ring Side Clearance, in (mm) ............... 0.0011-0.0027 (0.030-0.070)
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 Surface Distortion Flatness, in (mm) ............... 0.0019 (0.050)
Cylinder Block Top Surface Flatness, in (mm) ............... 0.0019 (0.050)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.2582-0.2588 (6.560-6.575)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.2570-0.2578 (6.530-6.550)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0009-0.0021 (0.025-0.055)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0019-0.0033 (0.050-0.085)
Valve Guide Bushing Inner Diameter, in (mm) ............... 0.2598-0.2604 (6.600-6.615)
Valve Seat Contact Width, in (mm) ............... 0.0511-0.0708 (1.30-1.80)
Valve Face Angle ............... 45 degrees
Valve Seat Angle ............... 45 degrees
Valve Margin Head Thickness, in (mm) ............... 0.0393 (1.00)
Valve Spring Free Length, in (mm) ............... 1.6377 (41.60)
Camshaft Journal Outer Diameter (Front), in (mm) ............... 1.6515-1.6521 (41.950-41.965)
Camshaft Journal Outer Diameter (Center), in (mm) ............... 1.6122-1.6127 (40.950-40.965)
Camshaft Journal Outer Diameter (Rear), in (mm) ............... 1.4547-1.4553 (36.950-36.965)
Camshaft Bearing Oil Clearance, in (mm) ............... 0.0019-0.0039 (0.050-0.100)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.4716-0.4721 (11.980-11.993)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.4724-0.4731 (12.000-12.018)
Rocker Arm Shaft to Bushing Clearance, in (mm) ............... 0.0002-0.0014 (0.007-0.038)

Tightening Torques

Cylinder Head Bolts (M12), lb-ft (Nm) ............... 87.0-94.0 (118.0-127.0)
Cylinder Head Bolts (M10), lb-ft (Nm) ............... 58.0-65.0 (78.5-88.0)
Connecting Rod Bearing Cap Nut, lb-ft (Nm) ............... 36.0-40.0 (49.0-54.0)
Main Bearing Cap Securing Bolts, lb-ft (Nm) ............... 36.2-43.4 (49.0-58.8)
Flywheel Securing Fastener Bolt, lb-ft (Nm) ............... 61.4-68.7 (83.3-93.1)
Crankshaft Front Center Pulley Nut, lb-ft (Nm) ............... 108.4-122.9 (147.0-166.6)
Camshaft Gear Retaining Lock Bolt, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Rocker Arm Shaft Bracket Support Nuts, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Cylinder Head Cover Bonnet Cap Nut, lb-ft (Nm) ............... 3.6-5.1 (4.9-6.9)
Oil Pan Drain Plug Fitting Bolt, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Oil Pan Housing Mounting Flange Bolts, lb-ft (Nm) ............... 5.8-7.2 (7.8-9.8)
Timing Gear Case Cover Mounting Bolts, lb-ft (Nm) ............... 5.8-7.2 (7.8-9.8)
Injection Pump Housing Mounting Flange Nuts, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Fuel Injection Nozzle Holder to Cylinder Head, lb-ft (Nm) ............... 36.1-43.4 (49.0-58.8)
Fuel Injection Pipe Union Coupling Flare Nut, lb-ft (Nm) ............... 18.0-21.6 (24.5-29.4)
Nozzle Leak-Off Return Line Banjo Fitting Bolt, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Glow Plug Terminal Body Hex Installation Fitting, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Glow Plug Electrical Power Cable Harness Nuts, lb-ft (Nm) ............... 1.0-1.5 (1.3-2.0)
Water Pump Assembly Housing Core Mounting Bolts, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Thermostat Housing Case Flange Cover Screws, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Cooling Fan Blade Assembly to Pulley Hub Bolts, lb-ft (Nm) ............... 5.8-7.2 (7.8-9.8)
Exhaust Manifold Heat Shield Mounting Studs, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Intake Manifold Runner Pipe Intake Port Bolts, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Oil Pressure Switch Sensor Sending Unit, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Alternator Pivot Base Through Bolt, lb-ft (Nm) ............... 21.6-28.9 (29.4-39.2)
Alternator Slotted Tension Adjuster Brace Bolt, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Starter Motor Housing Mounting Flange Studs, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Flywheel Housing Plate to Cylinder Block Bolts, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Oil Pump Assembly Base Plate Fixing Screws, lb-ft (Nm) ............... 5.1-7.2 (6.9-9.8)
Oil Pump Pressure Relief Valve Cap Screw, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Crankcase Breather Valve Baffle Cover Hex Cap, lb-ft (Nm) ............... 3.6-5.1 (4.9-6.9)
Fuel Lift Diaphragm Pump Base Fixing Studs, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Injection Pump Delivery Valve Holder Body, lb-ft (Nm) ............... 25.3-28.9 (34.3-39.2)
Fuel Filter Bracket Mounting Frame Fasteners, lb-ft (Nm) ............... 14.4-21.6 (19.6-29.4)
Engine Support Mount Brackets to Engine Block, lb-ft (Nm) ............... 32.5-39.7 (44.1-53.9)
Idler Gear Shaft Support Thrust Plate Screws, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Water Drain Cock Plug Fitting in Cylinder Block, lb-ft (Nm) ............... 14.4-21.6 (19.6-29.4)
Air Intake Glow Plug Pre-heater Element, lb-ft (Nm) ............... 21.6-28.9 (29.4-39.2)

________________________________________________________________________________________

• Mitsubishi Engines Specs
  
• Mitsubishi K3A Specs
  
• Mitsubishi K3B Specs
  
• Mitsubishi K3D Specs
  
• Mitsubishi KE70 Specs
  
• Mitsubishi KE75 Specs
  

________________________________________________________________________________

________________________________________________________________________________________

_______________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________