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Yanmar 3TN66UJ Engine

The Yanmar 3TN66UJ is a four-stroke vertical three-cylinder indirect injection naturally aspirated liqiud-cooled diesel engine from TN series. A 40.2 cubic inches (0.7 L) engine has a cylinder bore of 2.60" (66 mm), piston stroke of 2.53" (64.2 mm), and rated power of 15 Hp (11 kW) at 3300 rpm. The compression ratio rating is 23:1. The Yanmar 3TN66UJ engine is equipped with a mechanical fuel injection pump, dry element air cleaner with precleaner, full pressure lubrication system, and starting system with electric starter. The operating weight is 170 lbs (77 kg).

General Technical Data

Engine Specs

Engine Model ................ Yanmar 3TN66UJ
Engine Type ................ 4-Cycle indirect injection liquid-cooled diesel
Number of Cylinders ................ 3
Cylinder Bore, in (mm) ................ 2.60 (66.0)
Piston Stroke, in (mm) ................ 2.53 (64.2)
Total Displacement, cu.in (L) ................ 40.2 (0.66)
Rated Engine Power, hp (kW) ................ 15.0 (11.0)
Fast Idle Speed, rpm ................ 3350
Slow Idle Speed, rpm ................ 1450
Aspiration Type ................ Naturally aspirated
Compression Ratio ................ 23:1
Firing Order ................ 1-3-2
Air Cleaner Type ................ Dry element with precleaner
Lubrication System ................ Full pressure
Oil Filter Type ................ Full flow, replaceable
Electrical System Rating, Volts ................ 12
Charging System ................ Alternator
Alternator Rating, Amps ................ 35-40

Fuel System

Fuel System .................. Indirect injection
Fuel Pump Type .................. Mechanical
Governor Type .................. Mechanical
Fuel Filter Type .................. Replaceable element
Fuel Type .................. Diesel Fuel

Dimensions and Weight

Overall Lenght, in (mm) .................. 21.3 (540)
Overall Width, in (mm) .................. 16.9 (430)
Overall Height, in (mm) .................. 23.2 (590)
Net Weight, lbs (kg) .................. 170 (77)

Maintenance Data

Engine Oil

Engine Oil Type (Summer) .................. SAE 15W-30, 15W-40
Engine Oil Type (Winter) .................. SAE 5W-20, 5W-30
API Service Classifications .................. CE or CD
Engine Oil Capacity, qts (L) .................. 2.65 (2.50)

Cylinder and Valves

Cylinder Compression, psi (MPa) .................. 355 (2.45)
Intake Valve Clearance, mm (in) .................. 0.20 (0.008)
Exhaust Valve Clearance, mm (in) .................. 0.20 (0.008)

Fuel System and Coolant Capacity

Injection Pump Timing, deg ................ 13, BTDC
Fuel Injection Nozzle Pressure, kPa (psi) ................ 11722±480 (1700±70)
Fuel Supply Pump Pressure, kPa (psi) ................ 34-69 (5-10)
Coolant Capacity (Engine), qts (L) .................. 4.0 (3.8)

Service Specifications

Cylinder Block

Cylinder Bore Clearance, mm (in) ................ 0.25 (0.010)
Cylinder Bore I.D (Std), mm (in) ................ 66.00-66.03 (2.599-2.600)
Cylinder Bore I.D (Wear Limit), mm (in) ................ 66.20 (2.606)
Crankshaft End Play, mm (in) ................ 0.090-0.271 (0.004-0.011)
Crankshaft Main Bearing Clearance, mm (in) ................ 0.020-0.072 (0.0008-0.0028)
Connecting Rod Journal O.D (Std), mm (in) ................ 35.97-35.98 (1.4161-1.4165)
Connecting Rod Journal O.D (Wear Limit), mm (in) ................ 35.92 mm (1.414)
Connecting Rod Bearing Clearance, mm (in) ................ 0.020-0.072 (0.0008-0.0028)
Main Bearing Journal O.D (Std), mm (in) ................ 39.97-39.98 (1.5736-1.5740)
Main Bearing Journal O.D (Wear Limit), mm (in) ................ 39.92 (1.572)
Main Bearing Clearance, mm (in) ................ 0.15 (0.0059)
Main Bearing I.D (Std), mm (in) ................ 44.00-44.042 (1.732-1.734)
Main Bearing I.D (Wear Limit), mm (in) ................ 44.07 (1.735)
Piston O.D (Std), mm (in) ................ 65.927-65.957 (2.596-2.597)
Piston O.D (Wear Limit), mm (in) ................ 65.85 (2.593)
Piston O.D (0.25 mm Oversize), mm (in) ................ 66.18-66.21 (2.606-2.607)
Piston O.D (0.50 mm Oversize), mm (in) ................ 66.43-66.46 (2.615-2.616)
Piston Pin O.D (Std), mm (in) ................ 19.991-20.00 (0.787-0.788)
Piston Pin O.D (Wear Limit), mm (in) ................ 19.975 (0.786)
Piston Pin Bore Clearance, mm (in) ................ 0.045 (0.0018)
Piston Pin Bore I.D (Std), mm (in) ................ 20.00-20.008 (0.787-0.788)
Piston Pin Bore I.D (Wear Limit), mm (in) ................ 20.02 (0.788)
Piston Pin Bushing Clearance, mm (in) ................ 0.110 (0.0043)
Piston Pin Bushing I.D (Std), mm (in) ................ 20.025-20.038 (0.788-0.789)
Piston Pin Bushing I.D (Wear Limit), mm (in) ................ 20.10 (0.781)
Top Ring Groove Clearance, mm (in) ................ 0.065-0.100 (0.0026-0.0039)
Second Ring Groove Clearance, mm (in) ................ 0.030-0.065 (0.0012-0.0026)
Oil Ring Groove Clearance, mm (in) ................ 0.020-0.055 (0.0008-0.0022)
Top Ring End Gap, mm (in) ................ 0.15-0.35 (0.006-0.014)
Second Ring End Gap, mm (in) ................ 0.25-0.40 (0.010-0.016)
Oil Ring End Gap, mm (in) ................ 0.15-0.35 (0.006-0.014)

Cylinder Head and Valves

Cylinder Head (Max Out of Flatness), mm (in) ................ 0.05 (0.002)
Valve Clearance (Cold), mm (in) ................ 0.20 (0.008)
Intake Valve Seat Width (Std), mm (in) ................ 1.15 (0.045)
Intake Valve Seat Width (Wear Limit), mm (in) ................ 1.65 (0.065)
Exhaust Valve Seat Width (Std), mm (in) ................ 1.41 (0.056)
Exhaust Valve Seat Width (Wear Limit), mm (in) ................ 1.91 (0.075)
Intake and Exhaust Valves Faces, mm (in) ................ 0.51 (0.020)
Exhaust Valve Face Angle, deg ................ 45
Intake Valve Face Angle, deg ................ 30
Intake Valve Stem O.D (Std), mm (in) ................ 5.46-5.48 (0.2149-0.2157)
Exhaust Valve Stem O.D (Std), mm (in) ................ 5.44-5.46 (0.2142-0.2149)
Valve Stem O.D (Wear Limit), mm (in) ................ 5.40 (0.2126)
Valve Guide I.D (Maximum Clearance), mm (in) ................ 0.20 (0.008)
Valve Guide I.D (Std), mm (in) ................ 5.50-5.52 (0.216-0.217)
Valve Guide I.D (Wear Limit), mm (in) ................ 5.58 (0.220)
Valve Springs Free Length, mm (in) ................ 27.99 (1.102)
Exhaust Valve Seat Angle, deg ................ 45
Intake Valve Seat Angle, deg ................ 30
Camshaft Side Clearance, mm (in) ................ 0.05-0.15 (0.0020-0.0060)
Camshaft End Play, mm (in) ................ 0.05-0.20 (0.0020-0.0079)
Cam Lobe Height, mm (in) ................ 29.97-30.03 (1.180-1.182)
Camshaft Journal O.D (Gear Housing), mm (in) ................ 35.94-35.96 (1.4150-1.4157)
Camshaft Journal O.D (Flywheel), mm (in) ................ 35.94-35.96 (1.4150-1.4157)
Camshaft Journal O.D (Intermediate), mm (in) ................ 35.91-35.94 (1.4138-1.4150)
Camshaft Bushing I.D, mm (in) ................ 36.00-36.065 (1.417-1.420)
Camshaft Bushing Clearance, mm (in) ................ 0.18 (0.007)
Camshaft Bore I.D, mm (in) ................ 36.00-36.025 (1.417-1.418)
Rocker Arm Shaft O.D (Std), mm (in) ................ 9.97-9.99 (0.3925-0.3933)
Rocker Arm Shaft O.D (Wear Limit), mm (in) ................ 9.95 (0.3920)
Rocker Arm and Shaft Support Clearance, mm (in) ................ 0.14 (0.005)
Rocker Arm and Shaft Support I.D (Std), mm (in) ................ 10.00-10.02 (0.3937-0.3945)
Rocker Arm and Shaft Support I.D (Wear Limit), mm (in) ................ 10.09 (0.3972)

Tightening Torques

Rocker Arm Cover, Nm (lb-ft) ................ 18 (13.3)
Rocker Arm Assembly, Nm (lb-ft) ................ 26 (19.3)
Cylinder Head, Nm (lb-ft) ................ 34 (25)
Exhaust Manifold, Nm (lb-ft) ................ 11 (8.1)
Intake Manifold, Nm (lb-ft) ................ 11 (8.1)
Piston and Connecting Rod, Nm (lb-ft) ................ 23 (17)
Flywheel Housing Screw, Nm (lb-ft) ................ 49 (36)
Crankshaft Rear Oil Seal, Nm (lb-ft) ................ 11 (8.1)
Crankshaft and Main Bearings, Nm (lb-ft) ................ 54 (40)
Flywheel, Nm (lb-ft) ................ 83 (61)
Flywheel Housing, Nm (lb-ft) ................ 49 (36)
Camshaft, Nm (lb-ft) ................ 11 (8.1)
Timing Gear Cover, Nm (lb-ft) ................ 9 (6.7)
Crankcase Housing, Nm (lb-ft) ................ 22 (16.3)
Crankshaft Pulley, Nm (lb-ft) ................ 115 (85)
Oil Pump, Nm (lb-ft) ................ 25 (18)
Thermostat Cover, Nm (lb-ft) ................ 9 (6.7)
Water Pump, Nm (lb-ft) ................ 26 (19.3)
Fan Mounting, Nm (lb-ft) ................ 11 (8.1)
Fuel Injection Pump, Nm (lb-ft) ................ 20 (14.8)
Fuel Injection Nozzles, Nm (lb-ft) ................ 40 (30)

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