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Yanmar 2T90 Engine

The Yanmar 2T90 is a vertical, 2-cylinder, liquid-cooled, 4-stroke cycle diesel engine designed primarily for industrial and agricultural applications, most notably powering the gray-market Yanmar YM2210 tractor. Built with a heavy-duty cast-iron cylinder block, wet cylinder liners, and a cast-iron cylinder head, it shares significant structural DNA and components with its 3-cylinder counterpart, the 3T90. Field technicians and operators highly regard the engine for its reliable torque output, exceptional fuel efficiency, relatively low-noise operation, and a robust design that allows straightforward serviceability using basic mechanical tools.

The engine utilizes an overhead valve (OHV) configuration actuated by a gear-driven camshaft via pushrods and rocker arms. Each cylinder features one intake valve and one exhaust valve oriented vertically in the cylinder head. The valve train includes an integrated manual decompression lever assembly that lifts the exhaust valves to decrease cylinder resistance during manual or cold-weather cranking. Bore: 90 mm (3.54 inches). Stroke: 90 mm (3.54 inches). Total Displacement: 1.14 Liters (69.9 cubic inches).

The fuel system uses a mechanical pre-combustion chamber (swirl chamber) injection configuration. Fuel delivery begins at the fuel feed pump, drawing light diesel fuel from the fuel tank through a primary fuel filter/water separator to remove contaminants. Clean fuel is then supplied to a deck-mounted, multi-plunger mechanical fuel injection pump. The injection pump pressurizes the fuel and distributes it via high-pressure steel injection lines to the individual fuel injection valves (nozzles), which atomize the fuel directly into the pre-combustion chambers. Engine speed and fuel metering are controlled by a mechanical governor assembly linked directly to the fuel injection pump control rack.

Lubrication is managed via a full-pressure, wet-sump system driven by a trochoid-type lubricating oil pump. Oil is drawn from the lower oil pan through a wire-mesh intake strainer, then routed through a spin-on element oil filter before entering the primary oil gallery to feed the main bearings, connecting rod journals, and camshaft housing. An integrated oil pressure sender monitors system pressure. The engine incorporates a forced-circulation liquid cooling system to maintain optimum thermal efficiency. Coolant circulation is driven by a belt-driven centrifugal water pump that moves fluid through the passages of the cylinder block and cylinder head. Heat dissipation is handled via a front-mounted radiator with an attached mechanical cooling fan and an optional water replenishment overflow tank.

General Technical Data

Engine Specifications

Engine Model ............... Yanmar 2T90
Engine Type ............... 4-cycle vertical inline 2-cylinder liquid-cooled diesel
Number of Cylinders ............... 2
Cylinder Arrangement ............... Vertical inline
Engine Bore, in (mm) ............... 3.54 (90.0)
Engine Stroke, in (mm) ............... 3.54 (90.0)
Displacement, cu.in (L) ............... 69.9 (1.145)
Rated Power, hp (kW) ............... 21.7 (16.2)
Rated Speed, rpm ............... 2600
Max No-Load Speed, rpm ............... 2800-2850
Idle Speed, rpm ............... 700-800
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 20.0:1 to 21.5:1
Firing Order ............... 1-2
Combustion System ............... Direct injection or swirl chamber
Cylinder Block Material ............... Cast iron
Cylinder Head Material ............... Cast iron
Lubrication System ............... Forced pressure circulation via trochoid pump
Oil Pump Type ............... Trochoid rotor type gear-driven
Oil Filter Type ............... Full-flow cartridge paper element spin-on
Cooling System ............... Liquid circulation forced by centrifugal pump
Water Pump Type ............... Belt-driven centrifugal pump
Cooling Fan Type ............... Suction or pusher 4-blade plastic
Cooling Pump Drive ............... V-belt driven via crankshaft pulley
Air Cleaner Type ............... Heavy-duty dry type dual element paper filtration
Starting System ............... Electric starter motor engagement
Electrical System ............... 12V
Alternator Output ............... 15A to 35A

Fuel System

Fuel Injection Pump Model ............... Bosch type Deckel PFR inline
Fuel Feed Pump Type ............... Mechanical diaphragm lift pump
Fuel Injection Nozzle Architecture ............... Multi-hole throttling nozzle orifice system
Fuel Injection Pressure, psi (bar) ............... 2320-2465 (160.0-170.0)
Fuel Injection Timing, deg BTDC ............... 18.0 to 22.0
Fuel Filter Construction ............... Spin-on element with water trap sedimenter bowl
Fuel Return Architecture ............... Low-pressure return spill circuit back to main tank
Governor Type ............... All-speed mechanical centrifugal flyweight
Recommended Fuel Grade ............... ASTM D975 No. 2-D ultra-low sulfur diesel fuel
Fuel Transfer Pump Delivery Pressure, psi (bar) ............... 2.9-4.35 (0.2-0.3)
Injection Plunder Diameter, in (mm) ............... 0.236-0.275 (6.0-7.0)
Injection Plunger Stroke, in (mm) ............... 0.275-0.314 (7.0-8.0)
Nozzle Valve Seat Angle, deg ............... 60.0 to 90.0
Nozzle Spray Angle, deg ............... 4.0 to 15.0
Fuel Feed Line Internal Diameter, in (mm) ............... 0.157 (4.0)
Fuel Return Line Minimum Diameter, in (mm) ............... 0.118 (3.0)
Fuel Delivery Volume per Stroke, cu.in (cc) ............... 0.00183 (0.03)
Priming Pump Type ............... Manual plunger thumb pump

Dimensions and Weight

Overall Length, in (mm) ............... 18.5 (470)
Overall Width, in (mm) ............... 17.3 (440)
Overall Height, in (mm) ............... 21.6 (550)
Dry Weight, lbs (kg) ............... 243-276 (110-125)

Maintenance Data

Service Information

Cylinder Compression Pressure, psi (bar) ............... 426.7-455.1 (29.42-31.38)
Cylinder Compression Pressure, Limit, psi (bar) ............... 355.5 (24.51)
Maximum Compression Between Cylinders, psi (bar) ............... 28.4 (1.96)
Oil Pressure at Rated Speed, psi (bar) ............... 42.6-56.8 (2.94-3.92)
Oil Pressure at Low Idle Speed, psi (bar) ............... 8.5-14.2 (0.58-0.98)
Oil Pressure Relief Valve, psi (bar) ............... 56.8-71.1 (3.92-4.90)
Radiator Pressure Cap, psi (bar) ............... 12.8 (0.88)
Coolant Thermostat Crack-Open Temperature, F (C) ............... 158.0-165.2 (70.0-74.0)
Coolant Thermostat Full-Open Temperature, F (C) ............... 185.0 (85.0)
V-Belt Tension Deflection Limit, in (mm) ............... 0.39-0.59 (10.0-15.0)
Intake Valve Clearance (Cold), in (mm) ............... 0.0078 (0.20)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.0078 (0.20)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30, SAE 10W-30, or 15W-40
API Service Classifications ......................... CD, CE, CF, or CF-4
Engine Oil Capacity with Filter, qt (L) ............... 3.17-3.70 (3.0-3.5)
Engine Oil Capacity without Filter, qt (L) ............... 2.85-3.38 (2.7-3.2)
Cooling System Fluid Capacity, qt (L) ............... 4.22-5.28 (4.0-5.0)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 50 hours
Replace air cleaner ............... Every 250 hours
Replace fuel filter ............... Every 200 hours
Valve clearance adjustment ............... Every 500 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, in (mm) ............... 3.5433 (90.000)
Cylinder Bore Maximum Roundness, in (mm) ............... 0.00039 (0.010)
Cylinder Bore Taper Distortion, in (mm) ............... 0.00118 (0.030)
Crankshaft Main Journal Diameter, in (mm) ............... 2.5590-2.5594 (65.000-65.011)
Crankpin Outer Diameter, in (mm) ............... 2.1653-2.1657 (55.000-55.010)
Main Bearing Shell Clearance, in (mm) ............... 0.00149-0.00318 (0.038-0.081)
Connecting Rod Bearing Shell Clearance, in (mm) ............... 0.00137-0.00295 (0.035-0.075)
Crankshaft End Play, in (mm) ............... 0.00433-0.00826 (0.110-0.210)
Crankshaft Main Journal Out-of-Roundness, in (mm) ............... 0.00019 (0.005)
Connecting Rod Small End Bushing I.D, in (mm) ............... 1.0244-1.0251 (26.020-26.040)
Connecting Rod Small End to Bushing Clearance, in (mm) ............... 0.00078-0.00185 (0.020-0.047)
Connecting Rod Big End Side Play, in (mm) ............... 0.00393-0.01181 (0.100-0.300)
Piston Skirt Outer Diameter, in (mm) ............... 3.5393-3.5405 (89.900-89.930)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.00275-0.00393 (0.070-0.100)
Piston Pin Bore Inside Diameter, in (mm) ............... 1.0236-1.0240 (26.000-26.010)
Piston Pin Outer Diameter, in (mm) ............... 1.0233-1.0235 (25.993-26.000)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.00011-0.00043 (0.003-0.011)
Top Ring Groove Width, in (mm) ............... 0.0787-0.0795 (2.000-2.020)
Second Ring Groove Width, in (mm) ............... 0.0787-0.0795 (2.000-2.020)
Oil Ring Groove Width, in (mm) ............... 0.1574-0.1582 (4.000-4.020)
Top Ring Groove Side Clearance, in (mm) ............... 0.00157-0.00314 (0.040-0.080)
Second Ring Groove Side Clearance, in (mm) ............... 0.00157-0.00314 (0.040-0.080)
Oil Ring Groove Side Clearance, in (mm) ............... 0.00118-0.00275 (0.030-0.070)
Top Ring End Gap, in (mm) ............... 0.00984-0.01574 (0.250-0.400)
Second Ring End Gap, in (mm) ............... 0.00984-0.01574 (0.250-0.400)
Oil Ring End Gap, in (mm) ............... 0.00787-0.01574 (0.200-0.400)
Cylinder Head Gasket Surface Flatness Distortion, in (mm) ............... 0.00196 (0.050)
Cylinder Block Top Surface Flatness Distortion, in (mm) ............... 0.00196 (0.050)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.3129-0.3135 (7.950-7.965)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.3122-0.3129 (7.930-7.950)
Intake Valve Guide Inside Diameter, in (mm) ............... 0.3149-0.3155 (8.000-8.015)
Exhaust Valve Guide Inside Diameter, in (mm) ............... 0.3149-0.3155 (8.000-8.015)
Intake Valve Stem-to-Guide Clearance, in (mm) ............... 0.00137-0.00255 (0.035-0.065)
Exhaust Valve Stem-to-Guide Clearance, in (mm) ............... 0.00196-0.00334 (0.050-0.085)
Valve Head Thickness, in (mm) ............... 0.0393-0.0472 (1.000-1.200)
Valve Spring Free Length, in (mm) ............... 1.6535 (42.000)
Valve Seat Width, in (mm) ............... 0.0433-0.0551 (1.100-1.400)
Valve Seat Angle, deg ............... 90.0
Camshaft Journal Diameter (Front), in (mm) ............... 1.7716-1.7724 (45.000-45.020)
Camshaft Journal Diameter (Rear), in (mm) ............... 1.7716-1.7724 (45.000-45.020)
Camshaft Journal Bearing Clearance, in (mm) ............... 0.00196-0.00393 (0.050-0.100)
Cam Lobe Height (Intake), in (mm) ............... 1.4921-1.4960 (37.900-38.000)
Cam Lobe Height (Exhaust), in (mm) ............... 1.4921-1.4960 (37.900-38.000)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.4716-0.4722 (11.980-11.995)
Rocker Arm Bushing Inside Diameter, in (mm) ............... 0.4724-0.4731 (12.000-12.018)
Rocker Arm Shaft-to-Bushing Clearance, in (mm) ............... 0.00019-0.00149 (0.005-0.038)
Tappet Lifter Body Outer Diameter, in (mm) ............... 0.4704-0.4712 (11.950-11.970)
Tappet Guide Bore Inside Diameter, in (mm) ............... 0.4724-0.4731 (12.000-12.018)
Tappet Lifter Body-to-Guide Bore Clearance, in (mm) ............... 0.00118-0.00267 (0.030-0.068)

Tightening Torques

Cylinder Head Bolts (Stage One), lb-ft (Nm) ............... 21.6-28.9 (29.4-39.2)
Cylinder Head Bolts (Stage Two), lb-ft (Nm) ............... 43.3-50.6 (58.8-68.6)
Cylinder Head Bolts (Step Three), lb-ft (Nm) ............... 54.2-61.4 (73.5-83.3)
Main Bearing Cap Retaining Bolts, lb-ft (Nm) ............... 54.2-61.4 (73.5-83.3)
Connecting Rod Big End Cap Cap-Screws, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Flywheel Retaining Bolt, lb-ft (Nm) ............... 57.8-65.0 (78.4-88.2)
Crankshaft Front Pulley Center Core Damper Bolt, lb-ft (Nm) ............... 65.0-72.3 (88.2-98.0)
Camshaft Thrust Flange Retaining Hex Screws, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Timing Gear Case Cover Retaining Bolts, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Rocker Arm Shaft Support Bracket Nuts, lb-ft (Nm) ............... 21.6-25.3 (29.4-34.3)
Valve Cover Retaining Acorn Seal Nuts, lb-ft (Nm) ............... 5.0-7.2 (6.8-9.8)
Fuel Injection Pump Delivery Valve Holders, lb-ft (Nm) ............... 28.9-32.5 (39.2-44.1)
Fuel Injection Pump Housing Nuts, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Fuel Injection Nozzle Holder Assembly Cap Nut, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Fuel Injection Nozzle Body Fixing Retaining Nut, lb-ft (Nm) ............... 14.4-21.6 (19.6-29.4)
High Pressure Fuel Line Flare Gland Nuts, lb-ft (Nm) ............... 18.0-21.6 (24.5-29.4)
Fuel Return Spill Line Union Hollow Bolts, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Oil Sump Drain Plug Core Bolt, lb-ft (Nm) ............... 36.1-43.3 (49.0-58.8)
Oil Pressure Relief Valve Hex Cap Plug, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Oil Pump Assembly Back Cover Screws, lb-ft (Nm) ............... 5.0-7.2 (6.8-9.8)
Intake Manifold Runner Core Flange Bolts, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Exhaust Manifold Runner Heat Resistant Nuts, lb-ft (Nm) ............... 18.0-21.6 (24.5-29.4)
Water Pump Assembly Body Fastening Bolts, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Coolant Thermostat Housing Cap Screws, lb-ft (Nm) ............... 14.4-18.0 (19.6-24.5)
Radiator Coolant Hose Clamp Screws, lb-in (Nm) ............... 26.5-35.4 (3.0-4.0)
Electric Starter Motor Flange Mounting Bolts, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Alternator Pivot Adjustment Mounting Bolt, lb-ft (Nm) ............... 14.4-21.6 (19.6-29.4)
Oil Pressure Sensor Sender Switch, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Coolant Temperature Thermistor Sensor, lb-ft (Nm) ............... 14.4-21.6 (19.6-29.4)
Glow Plug Assembly Hex Base Core, lb-ft (Nm) ............... 10.8-14.4 (14.7-19.6)
Glow Plug Electrical Harness Terminal Nut, lb-in (Nm) ............... 8.8-13.2 (1.0-1.5)

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