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Yanmar 3TNA72UJ Engine

The Yanmar 3TNA72UJ is a 4-cycle 3-cylinder indirect injection naturally aspirated liqiud-cooled diesel engine from TNA series. A 53.6 cu.in (0.9 L) engine has a cylinder bore of 2.83" (72 mm), piston stroke of 2.83" (72 mm), and rated power of 17 Hp (12.7 kW) at 3600 rpm. The compression ratio rating is 22.3:1. The Yanmar 3TNA72UJ engine is equipped with a mechanical fuel injection pump, full pressure lubrication system, dry element air cleaner, and starting system with electric starter. The operating weight is 280 lbs (130 kg).

General Technical Data

Engine Specifications

Engine Model .................. Yanmar 3TNA72UJ
Engine Type .................. 4-Stroke 3-cylinder indirect injection diesel
Number of Cylinders .................. Three
Cylinder Bore, in (mm) .................. 2.83 (72.0)
Piston Stroke, in (mm) .................. 2.83 (72.0)
Displacement, L (cu.in) .................. 53.6 (0.88)
Rated Engine Power, hp (kW) .................. 17.0 (12.7)
Maximum Engine Power, hp (kW) .................. 22.0 (16.4)
Maximum Torque, Nm (ft-lb) .................. 47.6 (37)
Torque Speed, rpm .................. 2700
Fast Idle Speed, rpm .................. 3625
Slow Idle Speed, rpm .................. 1450
Aspiration Type .................. Naturally aspirated
Compression Ratio .................. 22.3:1
Firing Order .................. 1-3-2
Air Cleaner Type .................. Dry element
Lubrication System .................. Full pressure
Oil Filter Type .................. Full flow, replaceable
Cooling System .................. Liquid-cooled
Starting System .................. Electric Starter
Electrical System Rating, Volts .................. 12
Charging System .................. Alternator

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) .................. 19.8 (500)
Overall Width, in (mm) .................. 21.7 (550)
Overall Height, in (mm) .................. 16.7 (423)
Net Weight, lbs (kg) .................. 280 (130)

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) .......................... 3.3 (3.1)

Cylinder and Valves

Compression Pressure, psi (MPa) .......................... 356 (2.46)
Intake Valve Clearance, mm (in) .......................... 0.20 (0.008)
Exhaust Valve Clearance, mm (in) .......................... 0.20 (0.008)

Fuel System and Coolant Capacity

Fuel Injection Timing (BTDC), deg .......................... 13
Fuel injection Pressure, psi (MPa) .......................... 1700±70 (11.7±0.5)
Coolant Capacity (Engine), qts (L) .......................... 4.9 (4.7)

Service Specifications

Cylinder Block

Cylinder Bore I.D (Std), mm (in) .................. 72.00-72.03 (2.835-2.836)
Cylinder Bore I.D (Wear Limit), mm (in) .................. 72.20 (2.843)
Crankshaft Maximum Bend, mm (in) .................. 0.02 (0.0007)
Connecting Rod Journal O.D (Std), mm (in) .................. 39.97-39.98 (1.5736-1.5740)
Connecting Rod Journal O.D (Wear Limit), mm (in) .................. 39.92 (1.572)
Connecting Rod Bearing Clearance, mm (in) .................. 0.16 (0.006)
Connecting Rod Bearing I.D (Std), mm (in) .................. 40.00-40.042 (1.575-1.577)
Connecting Rod Bearing I.D (Wear Limit), mm (in) .................. 40.07 (1.578)
Main Bearing Journal O.D (Std), mm (in) .................. 43.97-43.98 (1.7311-1.7315)
Main Bearing Journal O.D (Wear Limit), mm (in) .................. 43.92 (1.729)
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) .................. 71.922-71.952 (2.832-2.833)
Piston O.D (Wear Limit), mm (in) .................. 71.81 (2.827)
Piston Pin O.D (Std), mm (in) .................. 20.991-21.00 (0.826-0.827)
Piston Pin O.D (Wear Limit), mm (in) .................. 20.975 (0.825)
Piston Pin Bore Clearance, mm (in) .................. 0.045 (0.0018)
Piston Pin Bore I.D (Std), mm (in) .................. 21.00-21.009 (0.8268-0.8271)
Piston Pin Bore I.D (Wear Limit), mm (in) .................. 21.02 (0.828)
Piston Pin Bushing Clearance, mm (in) .................. 0.110 (0.0043)
Piston Pin Bushing I.D (Std), mm (in) .................. 21.025-21.038 (0.8278-0.8282)
Piston Pin Bushing I.D (Wear Limit), mm (in) .................. 21.10 (0.831)
Piston to Cylinder Clearance, mm (in) .................. 0.61-0.79 (0.024-0.031)
Top Ring Groove Clearance, mm (in) .................. 0.075-0.110 (0.0030-0.0043)
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) .................. 0.10-0.25 (0.004-0.010)
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 Distortion (Std), mm (in) .................. 0.05 (0.002)
Cylinder Head Distortion (Wear Limit), mm (in) .................. 0.15 (0.006)
Intake Valve Seat Width (Std), mm (in) .................. 1.44 (0.057)
Intake Valve Seat Width (Wear Limit), mm (in) .................. 1.98 (0.078)
Exhaust Valve Seat Width (Std), mm (in) .................. 1.77 (0.070)
Exhaust Valve Seat Width (Wear Limit), mm (in) .................. 2.27 (0.089)
Intake Valve Seat Angle, deg .................. 30
Exhaust Valve Seat Angle, deg .................. 45
Intake Valve Face Angle, deg .................. 30
Exhaust Valve Face Angle, deg .................. 45
Intake Valve Stem O.D (Std), mm (in) .................. 6.94-6.96 (0.2732-0.2740)
Intake Valve Stem O.D (Wear Limit), mm (in) .................. 6.90 (0.2717)
Exhaust Valve Stem O.D (Std), mm (in) .................. 6.94-6.96 (0.2732-0.2740)
Exhaust Valve Stem O.D (Wear Limit), mm (in) .................. 6.90 (0.2717)
Intake Valve Guide I.D (Std), mm (in) .................. 7.00-7.02 (0.275-0.276)
Intake Valve Guide I.D (Wear Limit), mm (in) .................. 7.08 (0.279)
Exhaust Valve Guide I.D (Std), mm (in) .................. 7.00-7.02 (0.275-0.276)
Exhaust Valve Guide I.D (Wear Limit), mm (in) .................. 7.08 (0.279)
Intake Valve Stem to Valve Guide Clearance, mm (in) .................. 0.20 (0.008)
Exhaust Valve Stem to Valve Guide Clearance, mm (in) .................. 0.20 (0.008)
Intake Valve Springs Free Length, mm (in) .................. 37.40 (1.472)
Exhaust Valve Springs Free Length, mm (in) .................. 37.40 (1.472)
Camshaft Bushing I.D, mm (in) .................. 40.00-40.065 (1.575-1.577)
Camshaft Bushing Clearance, mm (in) .................. 0.18 (0.007)
Camshaft Bore I.D, mm (in) .................. 40.00-40.025 (1.575-1.576)
Intake Lobe Height, mm (in) .................. 33.95-34.05 (1.337-1.341)
Exhaust Lobe Height, mm (in) .................. 33.95-34.05 (1.337-1.341)

Tightening Torque Specs

Rocker Arm Cover .................. 18 Nm (160 lb-in)
Rocker Arm Assembly .................. 26 Nm (226 lb-in)
Cylinder Head (Final) .................. 61 Nm (45 lb-ft)
Exhaust Manifold .................. 26 Nm (30 lb-in)
Intake Manifold .................. 11 Nm (97 lb-in)
Piston and Connecting Rod .................. 23 Nm (203 lb-in)
Flywheel Housing .................. 49 Nm (36 lb-ft)
Crankshaft Bearing .................. 79 Nm (58 lb-ft)
Flywheel .................. 83 Nm (61 lb-ft)
Camshaft .................. 11 Nm (96 lb-in)
Timing Gear Cover .................. 9 Nm (78 lb-in)
Crankshaft Pulley .................. 115 Nm (85 lb-ft)
Oil Pump .................. 25 Nm (18 lb-ft)
Thermostat Cover .................. 26 Nm (226 lb-in)
Water Pump .................. 26 Nm (226 lb-in)
Fan Mounting .................. 11 Nm (96 lb-in)
Fuel Injection Pump .................. 20 Nm (180 lb-in)
Fuel Injection Nozzles .................. 40 Nm (30 lb-ft)

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