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Yanmar 3TG66UJ Engine

General Technical Data

Engine Specifications

Engine Model ............... Yanmar 3TG66UJ
Engine Type ............... 4-cycle inline 3-cylinder liquid-cooled gasoline
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 2.60 (66.0)
Engine Stroke, in (mm) ............... 2.53 (64.2)
Displacement, cu.in (L) ............... 40.2 (0.658)
Rated Engine Power, hp (kW) ............... 18.0 (13.4)
Rated Engine Speed, rpm ............... 3200
Peak Torque ............... 31.0 lb-ft (42.0 Nm) at 2400 rpm
Idle Speed ............... 900-1000 rpm
Operating Speed ............... 3200 rpm
Compression Ratio ............... 9.2:1
Firing Order ............... 1-2-3
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure
Oil Pump Type ............... Trochoid gear-driven
Oil Filter Type ............... Full-flow, spin-on
Cooling System ............... Liquid-cooled
Water Pump Type ............... Belt-driven, centrifugal
Air Cleaner Type ............... Dry dual-stage
Starting System ............... Electric Starter
Electrical System ............... 12V
Alternator Charging ............... 20A

Fuel System

Fuel Type ............... Gasoline
Fuel Delivery ............... Carburetor
Choke Type ............... Manual or Automatic configuration
Fuel Pump Type ............... Mechanical diaphragm
Fuel Pump Pressure, psi (kPa) ............... 2.2-3.6 (15.1-24.8)
Fuel Filter Type ............... Inline cartridge
Governor Type ............... Centrifugal all-speed mechanical
Governor Linkage ............... Mechanical rod and spring
Recommended Fuel Grade ............... 87 Octane unleaded gasoline
Maximum Fuel Consumption, gal/hr (L/hr) ............... 1.45 (5.5)

Dimensions and Weight

Engine Length, in (mm) ............... 15.6 (395)
Engine Width, in (mm) ............... 16.1 (410)
Engine Height, in (mm) ............... 19.8 (505)
Dry Weight, lbs (kg) ............... 135 (61)
Wet Weight, lbs (kg) ............... 146 (66)

Maintenance Data

Service Information

Cylinder Compression Pressure, Standard, psi (kPa) ............... 170.0 (1172.0)
Cylinder Compression Pressure, Limit, psi (kPa) ............... 142.0 (979.0)
Oil Pressure at Low Idle, psi (kPa) ............... 14.5 (100.0)
Oil Pressure at Rated Speed, psi (kPa) ............... 43.5-58.0 (300.0-400.0)
Relief Valve Operating Pressure, psi (kPa) ............... 56.8 (392.0)
Thermostat Opening Temperature, F (C) ............... 160.0 (71.0)
Thermostat Full Open Temperature, F (C) ............... 185.0 (85.0)
Spark Plug Type ............... NGK BPR5ES or equivalent
Spark Plug Gap, in (mm) ............... 0.028-0.031 (0.7-0.8)
Ignition Timing ............... 20 deg BTDC at 3200 rpm
Intake Valve Clearance (Cold), in (mm) ............... 0.006 (0.15)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.006 (0.15)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, SAE 5W-20
API Service Classifications ......................... SH or SG
Engine Oil Capacity with Filter, qt (L) ............... 2.3 (2.2)
Engine Oil Capacity without Filter, qt (L) ............... 2.0 (1.9)
Cooling System Capacity, qt (L) ............... 1.1 (1.0)

Service Intervals

Change engine oil ............... Every 100 hours
Replace oil filter ............... Every 100 hours
Replace fuel filter ............... Every 250 hours
Service air filter ............... Every 50 hours
Replace air filter ............... Every 250 hours
Change coolant ............... Every 1000 hours
Valve-lash adjustment ............... Every 300 hours
Check fuel system ............... Every 300 hours
Replace spark plug ............... Every 300 hours
Belt inspection ............... Every 100 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 2.6000-2.6012 (66.000-66.030)
Cylinder Bore Maximum Wear Limit, in (mm) ............... 2.6063 (66.160)
Cylinder Bore Out-of-Round Limit, in (mm) ............... 0.0004 (0.010)
Connecting Rod Small End Bushing I.D, in (mm) ............... 0.7484-0.7492 (19.010-19.030)
Connecting Rod Big End Side Clearance, in (mm) ............... 0.0059-0.0138 (0.150-0.350)
Crankshaft Main Journal Outer Diameter, in (mm) ............... 1.6524-1.6531 (41.970-41.990)
Crankpin Standard Outer Diameter, in (mm) ............... 1.4949-1.4957 (37.970-37.990)
Crankshaft Main Bearing Clearance, in (mm) ............... 0.0015-0.0031 (0.038-0.078)
Crankpin Bearing Clearance, in (mm) ............... 0.0014-0.0029 (0.035-0.074)
Crankshaft End Play, in (mm) ............... 0.0043-0.0091 (0.110-0.230)
Piston Skirt Outer Diameter, in (mm) ............... 2.5961-2.5972 (65.940-65.970)
Piston to Cylinder Bore Clearance, in (mm) ............... 0.0024-0.0035 (0.060-0.090)
Piston Pin Bore Inner Diameter, in (mm) ............... 0.7480-0.7484 (19.000-19.010)
Piston Pin Outer Diameter, in (mm) ............... 0.7476-0.7480 (18.989-19.000)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0000-0.0008 (0.000-0.021)
Top Ring Groove Width, in (mm) ............... 0.0610-0.0618 (1.550-1.570)
Second Ring Groove Width, in (mm) ............... 0.0610-0.0618 (1.550-1.570)
Oil Ring Groove Width, in (mm) ............... 0.1114-0.1122 (2.830-2.850)
Top Ring Side Clearance, in (mm) ............... 0.0016-0.0028 (0.040-0.070)
Second Ring Side Clearance, in (mm) ............... 0.0012-0.0024 (0.030-0.060)
Oil Ring Side Clearance, in (mm) ............... 0.0012-0.0024 (0.030-0.060)
Top Ring End Gap, in (mm) ............... 0.0059-0.0118 (0.150-0.300)
Second Ring End Gap, in (mm) ............... 0.0059-0.0118 (0.150-0.300)
Oil Ring End Gap, in (mm) ............... 0.0079-0.0157 (0.200-0.400)
Cylinder Head Distortion Maximum Surface, in (mm) ............... 0.0020 (0.050)
Cylinder Block Top Surface Distortion Maximum, in (mm) ............... 0.0020 (0.050)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.2343-0.2348 (5.950-5.965)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.2339-0.2344 (5.940-5.955)
Valve Guide Inner Diameter, in (mm) ............... 0.2362-0.2367 (6.000-6.012)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0014-0.0024 (0.035-0.062)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0018-0.0028 (0.045-0.072)
Valve Sinkage from Cylinder Head Face, in (mm) ............... 0.0276-0.0354 (0.700-0.900)
Intake Valve Seat Angle, deg ............... 45
Exhaust Valve Seat Angle, deg ............... 45
Intake Valve Face Angle, deg ............... 45
Exhaust Valve Face Anglet, deg ............... 45
Valve Spring Free Length, in (mm) ............... 1.465 (37.2)
Camshaft Journal Outer Diameter, in (mm) ............... 1.4941-1.4949 (37.950-37.970)
Cam Lobe Height (Intake), in (mm) ............... 1.2583-1.2614 (31.960-32.040)
Cam Lobe Height (Exhaust), in (mm) ............... 1.2583-1.2614 (31.960-32.040)
Camshaft Journal Clearance, in (mm) ............... 0.0012-0.0028 (0.030-0.070)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.4717-0.4724 (11.980-12.000)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.4728-0.4740 (12.010-12.040)
Rocker Arm Shaft to Bushing Clearance, in (mm) ............... 0.0004-0.0024 (0.010-0.060)
Tappet Standard Outer Diameter, in (mm) ............... 0.8244-0.8252 (20.940-20.960)
Tappet Bore Standard Inner Diameter, in (mm) ............... 0.8268-0.8276 (21.000-21.020)
Tappet to Bore Clearance, in (mm) ............... 0.0016-0.0031 (0.040-0.080)

Tightening Torques

Cylinder Head Bolt (Initial Stage) ............... 22 lb-ft (30 Nm)
Cylinder Head Bolt (Final Stage) ............... 44 lb-ft (60 Nm)
Connecting Rod Cap Nut ............... 24 lb-ft (32 Nm)
Main Bearing Cap Bolt ............... 40 lb-ft (54 Nm)
Flywheel Bolt ............... 47 lb-ft (64 Nm)
Crankshaft Pulley Bolt ............... 65 lb-ft (88 Nm)
Camshaft Thrust Plate Bolt ............... 9 lb-ft (12 Nm)
Camshaft Gear Bolt ............... 22 lb-ft (30 Nm)
Rocker Arm Shaft Support Bolt ............... 22 lb-ft (30 Nm)
Valve Cover Nut ............... 7 lb-ft (10 Nm)
Oil Pan Mounting Bolt ............... 9 lb-ft (12 Nm)
Oil Drain Plug ............... 36 lb-ft (49 Nm)
Spark Plug ............... 18 lb-ft (25 Nm)
Carburetor Mounting Nut ............... 14 lb-ft (19 Nm)
Intake Manifold Bolt ............... 9 lb-ft (12 Nm)
Exhaust Manifold Bolt ............... 18 lb-ft (25 Nm)
Water Pump Mounting Bolt ............... 9 lb-ft (12 Nm)
Starter Motor Mounting Bolt ............... 33 lb-ft (45 Nm)
Alternator Mounting Pivot Bolt ............... 22 lb-ft (30 Nm)
Alternator Adjusting Brace Bolt ............... 14 lb-ft (19 Nm)
Oil Pressure Switch ............... 11 lb-ft (15 Nm)
Coolant Temperature Sensor ............... 18 lb-ft (25 Nm)
Flywheel Housing Bolt ............... 22 lb-ft (30 Nm
Timing Gear Case Cover Bolt ............... 9 lb-ft (12 Nm)
Governor Housing Bolt ............... 9 lb-ft (12 Nm)
Fuel Pump Mounting Bolt ............... 14 lb-ft (19 Nm)

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