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Shibaura S753 Engine

The Shibaura S753 is a compact, vertical, in-line 3-cylinder, 4-stroke diesel engine designed primarily for sub-compact tractors, agricultural machinery, and small industrial equipment like mini-excavators and loaders. Engineered with a focus on high structural rigidity and low operational noise, this liquid-cooled engine features an easy-maintenance design where all critical service checkpoints (including the oil fill, dipstick, and oil filter) are strategically grouped on the right-hand side.

The cylinder head utilizes an overhead valve configuration containing a total of 6 valves (2 valves per cylinder: 1 intake, 1 exhaust). Service clearances must be set under cold engine conditions: Intake Valve Clearance: 0.008 inches (0.203 mm). Exhaust Valve Clearance: 0.008 inches (0.203 mm). Bore: 75 mm (2.953 inches). Stroke: 72 mm (2.835 inches). Total Displacement: 0.954 Liters (58.2 cubic inches).

Fuel System: The engine features a mechanical direct or indirect injection system designed for standard diesel fuel. Fuel delivery is handled by a mechanical diaphragm-type fuel lift pump that draws fuel from the storage tank, passing it through a high-efficiency fuel filter and water separator element before feeding the inline multi-plunger injection pump. Glow plugs are integrated into the cylinder head to assist with pre-heating the combustion chambers for reliable cold weather starting.

The engine uses a full-pressure lubrication feed supplied by an internal oil pump to protect major rotating assemblies. Service Requirements: High-grade diesel engine oil accessible via the right-side service area, complete with a spin-on element oil filter. The thermal management setup consists of a forced liquid-cooling circuit. Circulation Mechanics: An external belt-driven centrifugal water pump pushes coolant through designated cooling passages integrated within the engine block and cylinder head. Air movement is handled by a mechanical radiator fan attached to the water pump pulley hub assembly.

General Technical Data

Engine Specifications

Engine Model ............... Shibaura S753
Engine Type ............... 4-cycle vertical inline 3-cylinder liquid-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 2.953 (75.0)
Engine Stroke, in (mm) ............... 2.835 (72.0)
Displacement, cu.in (L) ............... 58.2 (0.954)
Rated Engine Power, hp (kW) ............... 18.0-21.0 (13.4-15.7)
Rated Engine Speed, rpm ............... 2500-3000
Peak Torque ............... 38.3-42.1 lb-ft (52.0-57.1 Nm) at 1800-2000 rpm
Idle Speed High, rpm ............... 3150-3250
Idle Speed Low, rpm ............... 1200-1300
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 23.0:1-24.0:1
Firing Order ............... 1-2-3
Rotation Direction ............... Counterclockwise viewed from flywheel end
Combustion Chamber Type ............... Swirl chamber indirect injection
Valve Mechanism ............... Overhead valve pushrod operated
Number of Valves Per Cylinder ............... 2
Total Number of Valves ............... 6
Crankcase Ventilation Type ............... Closed breather system
Cylinder Block Material ............... Cast iron
Cylinder Head Material ............... Cast iron
Lubrication System ............... Full-pressure lubrication
Oil Pump Type ............... Trochoid type gear-driven
Oil Filter Type ............... Full-flow spin-on cartridge
Cooling System ............... Forced circulation liquid-cooled
Water Pump Type ............... Belt-driven centrifugal impeller
Cooling Fan Type ............... Suction or pusher plastic 5-blade fan
Air Cleaner Type ............... Dry element dual-stage element
Glow Plug Type ............... Sheathed quick-heating type
Starting System ............... Electric motor starter
Electrical System, V ............... 12
Starter Output Power, hp (kW) ............... 1.6 (1.2)
Alternator Output, A ............... 40

Fuel System

Injection Pump Type ............... Bosch Bosch-type inline block pump
Fuel Injection Nozzle Type ............... Throttle type nozzle pintle mechanism
Injection Pump Drive Method ............... Camshaft driven gear assembly
Fuel Feed Pump Type ............... Mechanical diaphragm type lift pump
Fuel Injection Timing, deg BTDC ............... 19.0-21.0
Injection Opening Pressure, psi (MPa) ............... 1706-1849 (11.8-12.7)
Fuel Filter Type ............... Spin-on cartridge fuel-water separator
Recommended Fuel Grade ............... Ultra-low sulfur diesel ASTM D975 No.2-D
Fuel Delivery Pressure, psi (kPa) ............... 2.9-4.3 (20.0-30.0)
Governor Type ............... Mechanical centrifugal all-speed governor
Injection Pipe Inner Diameter, in (mm) ............... 0.059 (1.5)
Injection Pipe Outer Diameter, in (mm) ............... 0.236 (6.0)
Nozzle Holder Type ............... Screw-in assembly flange interface
Fuel Overflow System Valve Pressure, psi (kPa) ............... 21.3 (147.0)

Dimensions and Weight

Overall Length, in (mm) ............... 19.3 (490)
Overall Width, in (mm) ............... 15.7 (400)
Overall Height, in (mm) ............... 21.6 (550)
Dry Weight, lbs (kg) ............... 207 (94)
Operating Weight, lbs (kg) ............... 225 (102)

Maintenance Data

Service Information

Compression Pressure, Standard, psi (MPa) ............... 426.7 (2.94)
Compression Pressure, Minimum, psi (MPa) ............... 355.6 (2.45)
Compression Pressure Between Cylinders, psi (MPa) ............... 28.4 (0.196)
Oil Pressure at Low Idle, psi (kPa) ............... 14.2 (98.0)
Oil Pressure at Rated Speed, psi (kPa) ............... 42.6-56.8 (294.0-392.0)
Minimum Acceptable Oil Pressure, psi (kPa) ............... 9.9 (68.6)
Radiator Cap Pressure Rating, psi (kPa) ............... 12.8 (88.2)
Coolant Thermostat Opening Temperature, F (C) ............... 160.0 (71.0)
Coolant Thermostat Full Open Temperature, F (C) ............... 185.0 (85.0)
Intake Valve Clearance (Cold), in (mm) ............... 0.008 (0.203)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.008 (0.203)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30, SAE 10W-30, or 15W-40
API Service Classifications ......................... CF, CF-4, CH-4
Engine Oil Capacity with Filter, qt (L) ............... 3.5 (3.3)
Engine Oil Capacity without Filter, qt (L) ............... 3.17 (3.0)
Coolant Capacity, Engine Only, qt (L) ............... 3.7 (3.5)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 100 hours
Replace air cleaner ............... Every 600 hours
Replace fuel filter ............... Every 400 hours
Valve clearance adjustment ............... Every 400 hours
Fuel system inspection ............... Every 800 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 1000 hours
Clean radiator core ............... Every 250 hours
Inspect belt tension ............... Every 100 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 2.9527-2.9535 (75.000-75.020)
Cylinder Bore Max Wear Limit, in (mm) ............... 2.9606 (75.200)
Cylinder Roundness Max, in (mm) ............... 0.0004 (0.01)
Cylinder Head Surface Distortion, in (mm) ............... 0.002 (0.05)
Cylinder Block Top Surface Warpage, in (mm) ............... 0.002 (0.05)
Connecting Rod Big End Bearing I.D, in (mm) ............... 1.5752-1.5764 (40.010-40.040)
Connecting Rod Small End Bushing I.D, in (mm) ............... 0.8272-0.8280 (21.010-21.030)
Crankshaft Main Journal Outer Standard, in (mm) ............... 1.8492-1.8500 (46.970-46.990)
Crankshaft Main Journal Bushing Inner Diameter, in (mm) ............... 1.8512-1.8524 (47.020-47.050)
Crankshaft Main Journal Oil Clearance, in (mm) ............... 0.0012-0.0031 (0.030-0.080)
Crankpin Outer Diameter, in (mm) ............... 1.5736-1.5744 (39.970-39.990)
Crankpin Oil Clearance, in (mm) ............... 0.0008-0.0028 (0.020-0.070)
Crankshaft End Play, in (mm) ............... 0.0020-0.0059 (0.050-0.150)
Main Bearing Bore Inner Diameter, in (mm) ............... 2.0079-2.0087 (51.000-51.020)
Piston Outer Diameter, in (mm) ............... 2.9504-2.9512 (74.940-74.960)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0016-0.0031 (0.040-0.080)
Piston Pin Bore Inner Diameter, in (mm) ............... 0.8268-0.8272 (21.000-21.010)
Piston Pin Outer Diameter, in (mm) ............... 0.8264-0.8268 (20.990-21.000)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... -0.0002-0.0004 (-0.005-0.010)
Piston Pin to Con Rod Small End Bushing Clearance, in (mm) ............... 0.0004-0.0016 (0.010-0.040)
Top Ring Groove Width, in (mm) ............... 0.0787-0.0795 (2.000-2.020)
Second Ring Groove Width, in (mm) ............... 0.0591-0.0598 (1.500-1.520)
Oil Ring Groove Width, in (mm) ............... 0.1575-0.1583 (4.000-4.020)
Top Ring Groove Side Clearance, in (mm) ............... 0.0024-0.0039 (0.060-0.100)
Second Ring Groove Side Clearance, in (mm) ............... 0.0020-0.0035 (0.050-0.090)
Oil Ring Groove Side Clearance, in (mm) ............... 0.0009-0.0025 (0.025-0.065)
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)
Valve Stem Outer Diameter (Intake), in (mm) ............... 0.2736-0.2742 (6.950-6.965)
Valve Stem Outer Diameter (Exhaust), in (mm) ............... 0.2724-0.2732 (6.920-6.940)
Valve Guide Inner Diameter, in (mm) ............... 0.2756-0.2764 (7.000-7.020)
Valve Stem to Guide Clearance (Intake), in (mm) ............... 0.0014-0.0028 (0.035-0.070)
Valve Stem to Guide Clearance (Exhaust), in (mm) ............... 0.0024-0.0039 (0.060-0.100)
Valve Spring Free Length, in (mm) ............... 1.378 (35.00)
Valve Face Angle, deg ............... 45.0
Valve Seat Angle, deg ............... 45.0
Valve Sink Depth (Intake), in (mm) ............... 0.0276-0.0354 (0.70-0.90)
Valve Sink Depth (Exhaust), in (mm) ............... 0.0276-0.0354 (0.70-0.90)
Camshaft Journal Outer Diameter (Front), in (mm) ............... 1.5732-1.5740 (39.960-39.980)
Camshaft Journal Outer Diameter (Center), in (mm) ............... 1.5732-1.5740 (39.960-39.980)
Camshaft Journal Outer Diameter (Rear), in (mm) ............... 1.5732-1.5740 (39.960-39.980)
Camshaft Bearing Clearance, in (mm) ............... 0.0059 (0.150)
Cam Lobe Height (Intake), in (mm) ............... 1.3406-1.3425 (34.050-34.100)
Cam Lobe Height (Exhaust), in (mm) ............... 1.3406-1.3425 (34.050-34.100)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.4717-0.4724 (11.980-12.000)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.4732-0.4740 (12.020-12.040)
Rocker Arm Bushing to Shaft Clearance, in (mm) ............... 0.0008-0.0024 (0.020-0.060)
Tappet Outer Diameter, in (mm) ............... 0.8646-0.8654 (21.960-21.980)
Tappet Guide Hole Inner Diameter, in (mm) ............... 0.8661-0.8673 (22.000-22.030)
Tappet to Guide Hole Clearance, in (mm) ............... 0.0008-0.0028 (0.020-0.070)

Tightening Torques

Cylinder Head Bolts (1-Stage), lb-ft (Nm) ............... 25.3-28.9 (34.3-39.2)
Cylinder Head Bolts (2-Stage), lb-ft (Nm) ............... 54.2-57.8 (73.5-78.4)
Cylinder Head Bolts (3-Stage), lb-ft (Nm) ............... 72.3-75.9 (98.0-103.0)
Connecting Rod Cap Bolts, lb-ft (Nm) ............... 21.7-25.3 (29.4-34.3)
Main Bearing Cap Bolts, lb-ft (Nm) ............... 36.2-39.8 (49.0-54.0)
Flywheel Retaining Bolts, lb-ft (Nm) ............... 43.4-47.0 (58.8-63.7)
Crankshaft Pulley Center Nut, lb-ft (Nm) ............... 86.8-94.0 (117.7-127.5)
Camshaft Thrust Plate Fastening Bolts, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Camshaft Timing Gear Bolt, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Idler Gear Shaft Retaining Bolt, lb-ft (Nm) ............... 18.1-21.7 (24.5-29.4)
Timing Gear Case Cover Bolts, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Oil Pan Mounting Perimeter Bolts, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Oil Pan Drain Plug, lb-ft (Nm) ............... 25.3-32.5 (34.3-44.1)
Rocker Arm Shaft Bracket Holding Bolts, lb-ft (Nm) ............... 21.7-25.3 (29.4-34.3)
Rocker Arm Adjusting Screw Lock Nuts, lb-ft (Nm) ............... 10.1-13.7 (13.7-18.6)
Cylinder Head Valve Cover Acorn Nuts, lb-ft (Nm) ............... 5.1-8.7 (6.9-11.8)
Water Pump Mounting Fasteners, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Thermostat Housing Attachment Bolts, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Intake Manifold Flange Fixing Bolts, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Exhaust Manifold Flange Flanged Nuts, lb-ft (Nm) ............... 18.1-21.7 (24.5-29.4)
Fuel Injection Pump Delivery Valve Holders, lb-ft (Nm) ............... 25.3-28.9 (34.3-39.2)
Fuel Injection Pump Nuts to Block, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Fuel Injection Pump Gear Nut, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Fuel Injection Nozzle Assembly Holder Body, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Fuel Injection Nozzle Holder into Cylinder Head, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Fuel High-Pressure Injection Line Flare Nuts, lb-ft (Nm) ............... 18.1-21.7 (24.5-29.4)
Fuel Return Line Leak-Off Rail Nuts, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Glow Plug, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Glow Plug Power Supply Wire Terminal Nuts, lb-ft (Nm) ............... 1.1-1.4 (1.5-2.0)
Oil Pressure Sensor Unit, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Coolant Temperature Warning Switch, lb-ft (Nm) ............... 18.1-21.7 (24.5-29.4)
Starter Motor Flange Mounting Bolts, lb-ft (Nm) ............... 36.2-43.4 (49.0-58.8)
Alternator Pivoting Support Arm Tension Bolts, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Exhaust Outlet Pipe Adapter Stud Nuts, lb-ft (Nm) ............... 18.1-21.7 (24.5-29.4)
Oil Strainer Pick-up Tube Fasteners, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Crankcase Breather Valve Cap Screws, lb-ft (Nm) ............... 3.6-5.1 (4.9-6.9)
Fan Pulley Mounting Flange Cap Screws, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Flywheel Housing Shell Bolts, lb-ft (Nm) ............... 36.2-43.4 (49.0-58.8)

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