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Yanmar 2TR15 Engine

The Yanmar 2TR15 is a compact, naturally aspirated, vertical, two-cylinder utility diesel engine manufactured by Yanmar Holdings Co., Ltd. Originally introduced in the early 1970s, this heavy-duty, cast-iron engine series was predominantly utilized as the primary power unit for compact utility tractors, such as the Yanmar YM1500. Known for its robust, simplified construction, it employs a modular internal design shared with other variants in the TR family, providing reliable structural endurance for agricultural and small commercial operations.

Valve Configuration: Overhead valve (OHV) layout operated via standard mechanical pushrods and a single camshaft gear-driven off the crankshaft assembly. The configuration features a single intake valve and a single exhaust valve per cylinder, complete with mechanical rocker arms and manual top-side adjustment screws for setting valve clearance. Bore and Stroke: Features a cylinder bore diameter of 80.0 mm (3.15 in) paired with a piston stroke length of 85.0 mm (3.35 in). Total engine displacement measures 0.9 L (854 cc / 52.1 cu.in).

Fuel System: Employs an indirect mechanical diesel injection system featuring an external, multi-plunger inline fuel injection pump assembly timed directly to the engine gear train. Fuel is drawn from the supply tank through a mechanical primary fuel feed pump, routed through a replaceable spin-on fuel filter element, and delivered via high-pressure steel lines to mechanical fuel injection valves (injectors) seated in pre-combustion chambers inside the cylinder head. A mechanical governor assembly controls engine RPM via a dedicated speed control lever linked directly to the injection pump rack.

Lubrication System: Forced-feed, pressure-regulated system supplied by an internal gear-driven oil pump drawing from a stamped steel bottom oil pan. System routing directs pressurized oil through an external spin-on full-flow lube oil filter cartridge before supplying internal oil galleries feeding the main bearings, connecting rod journals, and upper valve train assemblies. Includes an integrated low oil pressure sending unit connected to the primary control instrumentation.

Cooling System: Liquid-cooled thermal management system utilizing an engine-driven centrifugal water pump to circulate coolant through the cylinder block water jackets and cylinder head passages. System flow is regulated by an inline mechanical thermostat to manage operating temperatures under load, typically relying on an external radiator assembly and mechanical belt-driven suction fan to dissipate core heat.

General Technical Data

Engine Specifications

Engine Model ............... Yanmar 2TR15
Engine Type ............... 4-stroke vertical inline 2-cylinder liquid-cooled diesel
Number of Cylinders ............... 2
Cylinder Arrangement ............... In-line vertical
Engine Bore, mm (in) ............... 80.0 (3.15)
Engine Stroke, mm (in) ............... 85.0 (3.35)
Displacement, L (cu.in) ............... 0.854 (52.1)
Rated Engine Power, kW (hp) ............... 11.2 (15.0)
Rated Engine Speed, rpm ............... 2400
Max No-Load Speed, rpm ............... 2600
Idle Speed, rpm ............... 700-800
Aspiration Type ............... Naturally aspirated
Compression Ratio ............... 23.0:1
Firing Order ............... 1-2
Combustion System ............... Indirect injection
Direction of Rotation ............... Counterclockwise viewed from flywheel
Cylinder Block Material ............... Cast iron
Cylinder Head Material ............... Cast iron
Lubrication System ............... Forced pressure circulation
Oil Pump Type ............... Trochoid or gear-driven rotor
Oil Filter Type ............... Full-flow spin-on cartridge
Cooling System ............... Liquid-cooled with centrifugal water pump
Water Pump Type ............... Belt-driven centrifugal
Air Cleaner Type ............... Oil bath or dry element dynamic type
Starting System ............... Electric starter motor
Electrical System, V ............... 12
Charging Alternator, A ............... 15-35
Starter Motor Power, kW (hp) ............... 1.0-1.4 (1.34-1.87)

Fuel System

Fuel Injection Pump Type ............... Bosch type in-line mini pump (Yanmar OEM)
Fuel Feed Pump Type ............... Mechanical diaphragm type
Fuel Injection Nozzle Type ............... Throttle or pintle type micro-orifice nozzle
Fuel Injection Pressure, MPa (psi) ............... 13.7-14.7 (1990-2130)
Fuel Injection Timing, deg BTDC ............... 21.0-23.0
Fuel Filter Type ............... Cartridge element with water sedimenter bowl
Governor Type ............... Mechanical centrifugal all-speed type
Fuel Delivery Line Material ............... High-pressure seamless steel tube
Injection Pump Plunger Diameter, mm (in) ............... 5.5 (0.216)
Injection Pump Plunger Stroke, mm (in) ............... 6.0 (0.236)
Nozzle Valve Diameter, mm (in) ............... 4.0 (0.157)
Nozzle Opening Spray Angle, deg ............... 4.0
Fuel Transfer Pump Delivery Pressure, MPa (psi) ............... 0.02-0.03 (2.9-4.3)

Dimensions and Weight

Overall Length, mm (in) ............... 520 (20.5)
Overall Width, mm (in) ............... 440 (17.3)
Overall Height, mm (in) ............... 560 (22.1)
Dry Weight, kg (lbs) ............... 68 (150)
Wet Weight, kg (lbs) ............... 75 (165)

Maintenance Data

Service Information

Compression Pressure, Standard, MPa (psi) ............... 2.94-3.14 (426-455)
Compression Pressure, Minimum, MPa (psi) ............... 2.45 (355)
Compression Pressure Between Cylinders, MPa (psi) ............... 0.29 (42)
Oil Pressure at Rated Speed, MPa (psi) ............... 0.29-0.39 (42.6-56.8)
Oil Pressure at Idle Speed, MPa (psi) ............... 0.05 (7.1)
Radiator Cap Relief Pressure, kPa (psi) ............... 88.2 (12.8)
Coolant Thermostat Starting to Open Temp, C (F) ............... 71.0 (159.8)
Coolant Thermostat Fully Open Target Temp, C (F) ............... 85.0 (185.0)
V-Belt Tension Slack Deflection, mm (in) ............... 10.0-12.0 (0.39-0.47)
Intake Valve Clearance, Cold, mm (in) ............... 0.20 (0.00787)
Exhaust Valve Clearance, Cold, mm (in) ............... 0.20 (0.00787)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30, SAE 10W-30, or SAE 5W-30
API Service Classifications ......................... CD, CE, or CF-4
Engine Oil Capacity with Filter, L (qt) ............... 2.2 (2.3)
Engine Oil Capacity without Filter, L (qt) ............... 2.0 (2.1)
Cooling System Fluid Capacity, L (qt) ............... 3.5 (3.7)

Service Intervals

Change oil and filter ............... Every 100 hours
Inspect air cleaner ............... Every 50 hours
Replace air cleaner ............... Every 300 hours
Replace fuel filter ............... Every 200 hours
Valve clearance adjustment ............... Every 300 hours
Fuel system inspection ............... Every 500 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 1000 hours
Clean radiator core ............... Every 200 hours
Inspect belt tension ............... Every 100 hours

Service Specifications

Cylinder Bore Inside Diameter, mm (in) ............... 80.000-80.030 (3.1496-3.1508)
Cylinder Bore Taper and Out of Round, mm (in) ............... 0.030 (0.0012)
Crankshaft Main Journal Outside Diameter, mm (in) ............... 50.000-50.020 (1.9685-1.9692)
Crankshaft Main Journal Bearings I.D, mm (in) ............... 50.040-50.075 (1.9700-1.9714)
Crankshaft Main Journal Bearing Clearance, mm (in) ............... 0.035-0.065 (0.00137-0.00255)
Crankpin Journal Diameter, mm (in) ............... 45.000-45.015 (1.7716-1.7722)
Crankshaft End Play, mm (in) ............... 0.110-0.210 (0.00433-0.00826)
Connecting Rod Small End Bushing I.D, mm (in) ............... 25.020-25.035 (0.9850-0.9856)
Connecting Rod Big End Bearing I.D, mm (in) ............... 45.035-45.065 (1.7730-1.7742)
Connecting Rod Big End Bearing Clearance, mm (in) ............... 0.030-0.060 (0.00118-0.00236)
Connecting Rod Big End Side Play, mm (in) ............... 0.150-0.250 (0.00590-0.00984)
Piston Skirt Outside Diameter, mm (in) ............... 79.940-79.960 (3.1472-3.1480)
Piston to Cylinder Bore Clearance, mm (in) ............... 0.050-0.080 (0.00196-0.00315)
Piston Pin Bore Inside Diameter, mm (in) ............... 25.000-25.010 (0.9842-0.9846)
Piston Pin to Piston Pin Bore Clearance, mm (in) ............... 0.000-0.015 (0.00000-0.00059)
Piston Pin to Con Rod Small End Clearance, mm (in) ............... 0.020-0.045 (0.00078-0.00177)
Top Ring Groove Width, mm (in) ............... 2.040-2.060 (0.0803-0.0811)
Second Ring Groove Width, mm (in) ............... 2.020-2.040 (0.0795-0.0803)
Oil Ring Groove Width, mm (in) ............... 4.015-4.035 (0.1581-0.1589)
Top Ring Side Clearance, mm (in) ............... 0.060-0.095 (0.00236-0.00374)
Second Ring Side Clearance, mm (in) ............... 0.050-0.085 (0.00196-0.00334)
Oil Ring Side Clearance, mm (in) ............... 0.030-0.065 (0.00118-0.00256)
Top Ring End Gap, mm (in) ............... 0.250-0.400 (0.00984-0.01574)
Second Ring End Gap, mm (in) ............... 0.200-0.350 (0.00787-0.01377)
Oil Ring End Gap, mm (in) ............... 0.200-0.400 (0.00787-0.01574)
Cylinder Head Flatness Distortion Surface Warpage, mm (in) ............... 0.05 (0.0019)
Cylinder Block Top Surface Flatness Distortion Warpage, mm (in) ............... 0.05 (0.0019)
Intake Valve Stem Outside Diameter, mm (in) ............... 7.955-7.970 (0.3131-0.3137)
Exhaust Valve Stem Outside Diameter, mm (in) ............... 7.940-7.955 (0.3125-0.3131)
Intake Valve Guide Inside Diameter, mm (in) ............... 8.000-8.015 (0.3149-0.3155)
Exhaust Valve Guide Inside Diameter, mm (in) ............... 8.000-8.015 (0.3149-0.3155)
Intake Valve Stem to Guide Clearance, mm (in) ............... 0.030-0.060 (0.00118-0.00236)
Exhaust Valve Stem to Guide Clearance, mm (in) ............... 0.045-0.075 (0.00177-0.00295)
Valve Face Angle, deg ............... 45.0
Valve Seat Angle, deg ............... 45.0
Intake Valve Head Thickness, mm (in) ............... 1.200 (0.0472)
Exhaust Valve Head Thickness, mm (in) ............... 1.200 (0.0472)
Valve Spring Free Length, mm (in) ............... 37.8 (1.488)
Camshaft Journal Outside Diameter (Gear Side), mm (in) ............... 42.000-42.020 (1.6535-1.6543)
Camshaft Journal Outside Diameter (Middle Side), mm (in) ............... 41.500-41.520 (1.6338-1.6346)
Camshaft Journal Outside Diameter (Flywheel Side), mm (in) ............... 41.000-41.020 (1.6141-1.6149)
Camshaft Journal Bushing Oil Clearance, mm (in) ............... 0.030-0.075 (0.00118-0.00295)
Cam Lobe Height (Intake), mm (in) ............... 33.650-33.750 (1.3248-1.3287)
Cam Lobe Height (Exhaust), mm (in) ............... 33.650-33.750 (1.3248-1.3287)
Rocker Arm Shaft Outside Diameter, mm (in) ............... 11.970-11.985 (0.4712-0.4718)
Rocker Arm Bushing Bore Inside Diameter, mm (in) ............... 12.000-12.020 (0.4724-0.4732)
Rocker Arm Bushing to Shaft Clearance, mm (in) ............... 0.015-0.050 (0.00059-0.00196)
Tappet Pushrod Lifter Bore Inside Diameter, mm (in) ............... 22.000-22.021 (0.8661-0.8669)
Tappet Lifter Body Outside Diamete, mm (in) ............... 21.972-21.993 (0.8650-0.8658)
Tappet Lifter Body to Guide Bore Clearance, mm (in) ............... 0.007-0.049 (0.00027-0.00192)

Tightening Torques

Cylinder Head Nuts (First Step), Nm (lb-ft) ............... 35.0 (25.8)
Cylinder Head Nuts (Final Step), Nm (lb-ft) ............... 73.5-78.5 (54.2-57.8)
Connecting Rod Big End Cap Bolts, Nm (lb-ft) ............... 44.1-49.0 (32.5-36.1)
Main Bearing Cap Nut, Nm (lb-ft) ............... 78.5-83.4 (57.8-61.5)
Flywheel Central Hardware Bolts, Nm (lb-ft) ............... 83.4-88.2 (61.5-65.0)
Crankshaft Front Pulley End Bolt, Nm (lb-ft) ............... 83.4-93.2 (61.5-68.7)
Camshaft Thrust Plate Retaining Bolt, Nm (lb-ft) ............... 22.5-27.5 (16.5-20.2)
Rocker Arm Shaft Support Bracket Nut Bolt, Nm (lb-ft) ............... 24.5-29.4 (18.0-21.6)
Valve Clearance Adjuster Jam Lock Nut, Nm (lb-ft) ............... 13.7-16.7 (10.1-12.3)
Fuel Injection Pump Delivery Valve Holder Nut, Nm (lb-ft) ............... 34.3-39.2 (25.3-28.9)
Fuel Injection Nozzle Retaining Union Cap Body, Nm (lb-ft) ............... 39.2-44.1 (28.9-32.5)
Fuel Injection Nozzle Holder Assembly RNut, Nm (lb-ft) ............... 49.0-53.9 (36.1-39.7)
Fuel Injection Pipe High Pressure Gland Nut, Nm (lb-ft) ............... 24.5-29.4 (18.0-21.6)
Fuel Feed Line Hollow Banjo Bolt Joining Fitting, Nm (lb-ft) ............... 11.8-14.7 (8.7-10.8)
Oil Pan Drain Plug Fitting Bottom Bolt, Nm (lb-ft) ............... 49.0-58.8 (36.1-43.3)
Oil Pressure Relief Control Valve Plug, Nm (lb-ft) ............... 39.2-44.1 (28.9-32.5)
Oil Pump Internal Rotor Casing Cover Screws, Nm (lb-ft) ............... 6.9-9.8 (5.0-7.2)
Front Timing Gear Case Cover Housing Bolts, Nm (lb-ft) ............... 22.5-27.5 (16.5-20.2)
Flywheel Housing Rear Plate Fastening Bolts, Nm (lb-ft) ............... 44.1-49.0 (32.5-36.1)
Intake Manifold Runner Pipe Attachment Flange Bolts, Nm (lb-ft) ............... 22.5-27.5 (16.5-20.2)
Exhaust Manifold Runner Pipe Attachment Flange Nuts, Nm (lb-ft) ............... 24.5-29.4 (18.0-21.6)
Water Pump Assembly Casing To Block Bolts, Nm (lb-ft) ............... 22.5-27.5 (16.5-20.2)
Coolant Thermostat Housing Casting Cap Bolts, Nm (lb-ft) ............... 22.5-27.5 (16.5-20.2)
Radiator Coolant Temperature Sensor Switch, Nm (lb-ft) ............... 19.6-24.5 (14.4-18.0)
Oil Pressure Gauge Sensor Switch, Nm (lb-ft) ............... 14.7-19.6 (10.8-14.4)
Glow Plug Preheater Element Screw Body, Nm (lb-ft) ............... 19.6-24.5 (14.4-18.0)
Glow Plug Terminal Power Wire Small Nut, Nm (lb-ft) ............... 1.5-2.5 (1.1-1.8)
Starter Motor Frame Mounting Bracket Flange Nuts, Nm (lb-ft) ............... 44.1-49.0 (32.5-36.1)
Charging Alternator Pivot Bracket Adjustment Bolt, Nm (lb-ft) ............... 22.5-27.5 (16.5-20.2)
Engine Oil Pan Perimeter Sheet Bolts, Nm (lb-ft) ............... 9.8-11.8 (7.2-8.7)
Cylinder Head Valve Cover Top Acorn Cap Nuts, Nm (lb-ft) ............... 6.9-9.8 (5.0-7.2)

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