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Komatsu 3D67E Engine

The Komatsu 3D67E is a heavy-duty, vertical, water-cooled, 4-cycle indirect injection (IDI) diesel engine designed primarily for compact construction equipment like mini-excavators. Engineered for durability and high-torque delivery in small-profile machine environments, it features an inline 3-cylinder configuration. The engine provides a balance of low emission output, high mechanical reliability, and smooth operation under variable load profiles common in tight workspace applications.

Valve Configuration: The engine utilizes an overhead valve (OHV) mechanism driven by a gear-train camshaft configuration. It features two valves per cylinder (one intake and one exhaust), regulated via pushrods and rocker arms for precise timing control. The engine has a precise cylinder bore diameter of 67.0 mm and a piston stroke length of 73.6 mm. This configuration results in a total displacement volume of 0.78 liters across all three cylinders.

Fuel System: Fuel management is governed by a Bosch MD-type mechanical mini-injection pump supplying fuel into a spherical E-TVCS type swirl combustion chamber for indirect injection. The assembly features specialized nozzle holders with high-pressure injectors, working alongside pre-heating glow plugs inside the combustion chambers to ensure clean ignition and smooth cold-weather startup operations.

Lubrication: Oil distribution relies on a forced lubrication system pressurized by a high-efficiency trochoid pump. The circuit includes an electrical pressure-indicating switch and filters the engine oil through a full-flow cartridge-type replaceable paper filter to protect internal components from operational debris. Cooling: Temperature regulation is handled through a liquid-cooled configuration using forced circulation via a centrifugal water pump coupled with a pressurized radiator. The cooling loop includes an engine-driven fan to effectively dissipate thermal load from the block and cylinder head under intensive operating conditions.

General Technical Data

Engine Specifications

Engine Model ............... Komatsu 3D67E-1A
Engine Type ............... 4-cycle inline 3-cylinder vertical direct injection liquid-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line vertical
Engine Bore, in (mm) ............... 2.64 (67.0)
Engine Stroke, in (mm) ............... 2.90 (73.6)
Displacement, cu.in (L) ............... 47.48 (0.778)
Rated Engine Power, hp (kW) ............... 15.0 (11.2)
Rated Engine Speed, rpm ............... 2600
Maximum No-Load Speed, rpm ............... 2800
Minimum No-Load Speed, rpm ............... 900-1000
Peak Torque, lb-ft (Nm) ............... 33.6 (45.6) at 2000 rpm
Idle Speed, rpm ............... 950
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 23.0:1
Firing Order ............... 1-3-2
Direction of Rotation ............... Counterclockwise viewed from flywheel side
Crankshaft Material ............... Forged steel induction hardened journals
Connecting Rod Material ............... Forged alloy steel die forged H-beam geometry
Camshaft Drive Mechanism ............... Helical gear train drive system
Valves Per Cylinder ............... 2
Cylinder Block Type ............... Monoblock cast iron high-strength alloy
Cylinder Head Type ............... Single-piece cast iron crossflow configuration
Combustion Chamber ............... Direct injection toroidal bowl in piston crown
Lubrication System ............... Forced lubrication with trochoid gear pump
Oil Pump Type ............... Crankshaft-driven trochoid gear type
Oil Filter Type ............... Full-flow, spin-on cartridge element
Cooling System ............... Forced circulation with centrifugal pump and radiator
Water Pump Type ............... V-belt driven centrifugal impeller pump
Air Cleaner Type ............... Dry dual-stage pleated paper element
Starting System ............... Electric starter motor engagement mechanism
Electrical System, V ............... 12
Alternator Capacity, A ............... 40
Starter Motor Power, hp (kW) ............... 1.47 (1.1)

Fuel System

Fuel Injection Pump Type ............... Bosch in-line mini pump config YPES type
Fuel Feed Pump Type ............... Mechanical diaphragm lift pump system
Fuel Injection Nozzle Type ............... Multi-hole mini nozzle assembly
Number of Nozzle Holes ............... 4
Nozzle Hole Diameter, in (mm) ............... 0.0079 (0.20)
Fuel Injection Pressure, psi (MPa) ............... 2842.0 (19.6)
Fuel Injection Timing, deg ............... 17.0 before top dead center
Fuel Filter Type ............... Spin-on cartridge element with water separator unit
Fuel Transfer Pump Pressure, psi (kPa) ............... 2.9-4.3 (20.0-30.0)
Maximum Fuel Inlet Restriction, in Hg (kPa) ............... 3.93 (13.3)
Maximum Fuel Return Restriction, in Hg (kPa) ............... 5.90 (20.0)
Fuel Injection Pipe Outer Diameter, in (mm) ............... 0.236 (6.0)
Fuel Injection Pipe Inner Diameter, in (mm) ............... 0.078 (2.0)
Fuel Return Line Diameter, in (mm) ............... 0.315 (8.0)
Governor Type ............... Mechanical centrifugal all-speed control governor
Injection Pump Plunger Diameter, in (mm) ............... 0.216 (5.5)
Injection Pump Plunger Stroke, in (mm) ............... 0.236 (6.0)
Fuel System Venting Method ............... Manual bleed screw filtration system
Recommended Fuel Grade ............... Ultra-low sulfur diesel ASTM D975 № 2-D

Dimensions and Weight

Overall Length, in (mm) ............... 19.5 (495)
Overall Width, in (mm) ............... 15.5 (395)
Overall Height, in (mm) ............... 21.1 (535)
Dry Weight, lbs (kg) ............... 166 (75)
Wet Weight, lbs (kg) ............... 179 (81)

Maintenance Data

Service Information

Compression Pressure, Standard, psi (MPa) ............... 426.0 (2.94) at 250 rpm
Compression Pressure, Limit, psi (MPa) ............... 341.0 (2.35) at 250 rpm
Compression Pressure Differential Between Cylinders, psi (MPa) ............... 28.4 (0.19)
Oil Pressure at Rated Speed, psi (kPa) ............... 42.6-56.8 (294.0-392.0)
Oil Pressure at Low Idle, psi (kPa) ............... 8.5 (58.8)
Maximum Oil Temperature, F (C) ............... 230.0 (110.0)
Normal Operating Coolant Temperature, F (C) ............... 176.0-194.0 (80.0-90.0)
Thermostat Opening Temperature, F (C) ............... 160.0 (71.0)
Thermostat Full-Open Temperature, F (C) ............... 185.0 (85.0)
V-Belt Tension Deflection, in (mm) ............... 0.39-0.55 (10.0-14.0)
Intake Valve Clearance (Cold), in (mm) ............... 0.0059-0.0098 (0.15-0.25)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.0059-0.0098 (0.15-0.25)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30, SAE 10W-30, or 15W-40
API Service Classifications ......................... CF or CH-4
Engine Oil Capacity with Filter, qt (L) ............... 2.95 (2.8)
Engine Oil Capacity, Sump Only, qt (L) ............... 2.53 (2.4)
Cooling System Fluid Capacity, qt (L) ............... 1.58 (1.5)

Service Intervals

Change oil and filter ............... Every 250 hours
Inspect air cleaner ............... Every 100 hours
Replace air cleaner ............... Every 1000 hours
Replace fuel filter ............... Every 500 hours
Valve clearance adjustment ............... Every 500 hours
Fuel system inspection ............... Every 1000 hours
Change coolant ............... Every 2000 hours
Compression test ............... Every 1000 hours
Clean radiator core ............... Every 250 hours
Inspect belt tension ............... Every 150 hours

Service Specifications

Cylinder Bore Inner Diameter, in (mm) ............... 2.6378-2.6382 (67.000-67.010)
Cylinder Bore Maximum Wear Limit, in (mm) ............... 2.6417 (67.100)
Cylinder Bore Out of Round Limit, in (mm) ............... 0.0004 (0.010)
Cylinder Bore Taper Maximum, in (mm) ............... 0.0004 (0.010)
Cylinder Block Upper Surface Flatness, in (mm) ............... 0.0019 (0.050)
Cylinder Head Lower Surface Flatness, in (mm) ............... 0.0019 (0.050)
Crankshaft Main Journal Diameter, in (mm) ............... 1.6515-1.6521 (41.950-41.965)
Crankshaft Main Bearing Clearance, in (mm) ............... 0.0014-0.0028 (0.038-0.072)
Crankpin Journal Diameter, in (mm) ............... 1.4941-1.4947 (37.950-37.965)
Crankshaft End Play Axial, in (mm) ............... 0.0043-0.0082 (0.110-0.210)
Connecting Rod Small End Bushing I.D, in (mm) ............... 0.7876-0.7881 (20.005-20.018)
Connecting Rod Big End Bearing Clearance, in (mm) ............... 0.0014-0.0027 (0.038-0.070)
Connecting Rod Side Clearance, in (mm) ............... 0.0059-0.0137 (0.150-0.350)
Piston Skirt Outer Diameter, in (mm) ............... 2.6358-2.6362 (66.950-66.960)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0015-0.0023 (0.040-0.060)
Piston Pin Bore Inside Diameter, in (mm) ............... 0.7874-0.7877 (20.000-20.009)
Piston Pin Outer Diameter, in (mm) ............... 0.7871-0.7874 (19.993-20.000)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0000-0.0006 (0.000-0.016)
Piston Pin to Small End Bushing Clearance, in (mm) ............... 0.0001-0.0009 (0.005-0.025)
Top Ring Groove Width, in (mm) ............... 0.0610-0.0618 (1.550-1.570)
Second Ring Groove Width, in (mm) ............... 0.0591-0.0598 (1.500-1.520)
Oil Ring Groove Width, in (mm) ............... 0.1181-0.1189 (3.000-3.020)
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 (0.150-0.300)
Second Ring End Gap, in (mm) ............... 0.0071-0.0130 (0.180-0.330)
Oil Ring End Gap, in (mm) ............... 0.0059-0.0137 (0.150-0.350)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.2342-0.2348 (5.950-5.965)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.2340-0.2346 (5.945-5.960)
Intake Valve Guide Inside Diameter, in (mm) ............... 0.2362-0.2367 (6.000-6.012)
Exhaust Valve Guide Inside Diameter, in (mm) ............... 0.2362-0.2367 (6.000-6.012)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0013-0.0024 (0.035-0.062)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0026 (0.040-0.067)
Valve Face Angle, deg ............... 45.0
Valve Seat Angle, deg ............... 45.0
Valve Head Thickness, in (mm) ............... 0.0393-0.0472 (1.000-1.200)
Valve Sinkage Depth, in (mm) ............... 0.0157-0.0275 (0.400-0.700)
Valve Spring Free Length, in (mm) ............... 1.4685 (37.300)
Camshaft Journal Outer Diameter, in (mm) ............... 1.4153-1.4161 (35.950-35.970)
Camshaft Bearing Inside Diameter, in (mm) ............... 1.4173-1.4185 (36.000-36.030)
Camshaft Oil Clearance, in (mm) ............... 0.0011-0.0031 (0.030-0.080)
Cam Lobe Height (Intake), in (mm) ............... 1.2578-1.2618 (31.950-32.050)
Cam Lobe Height (Exhaust), in (mm) ............... 1.2578-1.2618 (31.950-32.050)
Camshaft End Play, in (mm) ............... 0.0019-0.0059 (0.050-0.150)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.4716-0.4722 (11.982-11.994)
Rocker Arm Bushing Inside Diameter, in (mm) ............... 0.4724-0.4732 (12.000-12.020)
Rocker Arm Bushing to Shaft Clearance, in (mm) ............... 0.0002-0.0014 (0.006-0.038)
Tappet Outer Diameter, in (mm) ............... 0.8244-0.8251 (20.941-20.962)
Tappet Bore Inside Diameter, in (mm) ............... 0.8267-0.8275 (21.000-21.021)
Tappet to Block Clearance, in (mm) ............... 0.0014-0.0031 (0.038-0.080)

Tightening Torques

Cylinder Head Bolt, lb-ft (Nm) ............... 39.8-44.2 (54.0-60.0)
Connecting Rod Cap Bolt, lb-ft (Nm) ............... 16.6-20.2 (22.6-27.4)
Main Bearing Cap Bolt, lb-ft (Nm) ............... 36.1-41.9 (49.0-56.8)
Flywheel Mounting Bolt, lb-ft (Nm) ............... 43.4-47.7 (58.8-64.7)
Flywheel Housing Bolt, lb-ft (Nm) ............... 18.0-22.0 (24.5-29.8)
Crankshaft Pulley Bolt, lb-ft (Nm) ............... 61.4-68.7 (83.3-93.2)
Camshaft Thrust Plate Bolt, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Camshaft Gear Nut, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Rocker Shaft Support Bracket Bolt, lb-ft (Nm) ............... 18.0-22.0 (24.5-29.8)
Valve Cover Nut, lb-ft (Nm) ............... 5.1-7.2 (6.9-9.8)
Oil Pan Mounting Bolt, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Oil Pan Drain Plug, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Oil Pump Assembly Bolt, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Water Pump Mounting Bolt, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Thermostat Housing Bolt, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Intake Manifold Mounting Bolt, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Exhaust Manifold Mounting Bolt, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Fuel Injection Pump Drive Gear Nut, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Fuel Injection Pump Mounting Bolt, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Fuel Injection Nozzle Retaining Nut, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Fuel High Pressure Pipe Nut, lb-ft (Nm) ............... 18.0-21.6 (24.5-29.4)
Fuel Leak-off Line Joint Bolt, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Starter Motor Mounting Bolt, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Alternator Mounting Pivot Bolt, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Alternator Adjusting Link Bolt, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Glow Plug Torque Specification, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Oil Pressure Switch Sensor, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Coolant Temperature Sender Sensor, lb-ft (Nm) ............... 14.4-21.6 (19.6-29.4)

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