wsm wg972-e4 Workshop Manual
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wsm wg972-e4 Workshop Manual

Gasoline, lpg, natural gas
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WORKSHOP MANUAL
GASOLINE,LPG,
NATURAL GAS ENGINE
WG972-E4
(EFI)
KiSC issued 07, 2015 A

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Summary of Contents for wsm wg972-e4

  • Page 1 WORKSHOP MANUAL GASOLINE,LPG, NATURAL GAS ENGINE WG972-E4 (EFI) KiSC issued 07, 2015 A...
  • Page 2 TO THE READER This Workshop Manual tells the servicing personnel about the mechanism, servicing and maintenance of the WG972-E4. It contains 4 parts: "Information", "General", "Mechanism" and "Servicing".  Information This section contains information below. • Safety First • Specification •...
  • Page 3 INFORMATION KiSC issued 07, 2015 A...

  • Page 4: Table Of Contents

    INFORMATION CONTENTS 1. SAFETY FIRST ..........................I-1 2. SPECIFICATIONS.......................... I-4 3. EMISSION REGULATION......................I-7 [1] GENERAL ..........................I-7 [2] IMPORTANT ITEMS OF EXHAUST EMISSION REGULATION..........I-7 (1) Important Notice ......................... I-7 (2) Emission-Related Installation Instructions................I-7 4. PERFORMANCE CURVES......................I-8 5.

  • Page 5: Safety First

    INFORMATION WG972-E4, WSM 1. SAFETY FIRST SAFETY FIRST • This symbol, the industry's "Safety Alert Symbol", is used throughout this manual and on labels on the machine itself to warn of the possibility of personal injury. Read these instructions carefully.
  • Page 6 INFORMATION WG972-E4, WSM OPERATE SAFELY • Do not use the machine after you consume alcohol or medication or when you are tired. • Put on applicable clothing and safety equipment. • Use applicable tools only. Do not use alternative tools or parts.
  • Page 7 INFORMATION WG972-E4, WSM KEEP A GOOD AIRFLOW IN THE WORK AREA • If the engine is in operation, make sure that the area has good airflow. Do not operate the engine in a closed area. The exhaust gas contains poisonous carbon monoxide.

  • Page 8: Specifications

    INFORMATION WG972-E4, WSM 2. SPECIFICATIONS WG972-GL-E4 Model Gasoline Number of Cylinder Type Vertical, Water cooled, 4-cycle Dual Fuel (Gasoline/LPG) engine Bore × Stroke 74.5 × 73.6 mm (2.93 × 2.90 in.) Total Displacement 0.962 L (58.7 cu.in.) 17.6 kW / 3600 min (rpm) 16.3 kW / 3600 min...
  • Page 9 INFORMATION WG972-E4, WSM WG972-G-E4 Model Gasoline Number of Cylinder Type Vertical, Water cooled, 4-cycle Gasoline engine Bore × Stroke 74.5 × 73.6 mm (2.93 × 2.90 in.) Total Displacement 0.962 L (58.7 cu.in.) 18.7 kW / 3600 min (rpm) SAE Net Continuous 25.1 HP / 3600 min...
  • Page 10 INFORMATION WG972-E4, WSM WG972-L-E4 WG972-N-E4 Model Number of Cylinder Type Vertical, water cooled, 4-cycle LPG engine Vertical, water cooled, 4-cycle CNG engine Bore × Stroke 74.5 × 73.6 mm (2.93 × 2.90 in.) Total Displacement 0.962 L (58.7 cu.in.) 16.3 kW / 3600 min (rpm) 15.0 kW / 3600 min...

  • Page 11: Emission Regulation

    INFORMATION WG972-E4, WSM 3. EMISSION REGULATION [1] GENERAL Along with E4 models, are yet available to be used in the following countries per output category. North kW, Disp. Model Type Europe Japan America 19 < P ≤ 30, None WG972-E4...

  • Page 12: Performance Curves

    INFORMATION WG972-E4, WSM 4. PERFORMANCE CURVES WG972-GL-E4 (1) Torque (3) Engine Speed Gasoline Use LPG Use (2) B.S.F.C. (Brake Specific Fuel (4) Brake Horsepower Consumption) 9Y1211108INI0007US0 KiSC issued 07, 2015 A...
  • Page 13 INFORMATION WG972-E4, WSM WG972-G-E4 (1) Torque (2) B.S.F.C. (Brake Specific Fuel (3) Engine Speed (4) Brake Horsepower Consumption) 9Y1211108INI0014US0 KiSC issued 07, 2015 A...
  • Page 14 INFORMATION WG972-E4, WSM WG972-L-E4 (1) Torque (2) B.S.F.C. (Brake Specific Fuel (3) Engine Speed (4) Brake Horsepower Consumption) 9Y1211108INI0015US0 I-10 KiSC issued 07, 2015 A...
  • Page 15 INFORMATION WG972-E4, WSM WG972-N-E4 (1) Torque (2) B.S.F.C. (Brake Specific Fuel (3) Engine Speed (4) Brake Horsepower Consumption) 9Y1211108INI0016US0 I-11 KiSC issued 07, 2015 A...

  • Page 16: Dimensions

    INFORMATION WG972-E4, WSM 5. DIMENSIONS WG972-GL-E4 WG972-GL-E4 516 mm (20.3 in.) 393 mm (15.5 in.) 503 mm (19.8 in.) 9Y1211108INI0008US0 I-12 KiSC issued 07, 2015 A...
  • Page 17 INFORMATION WG972-E4, WSM WG972-G-E4 WG972-G-E4 453 mm (17.8 in.) 393 mm (15.5 in.) 503 mm (19.8 in.) 9Y1211108INI0009US0 I-13 KiSC issued 07, 2015 A...
  • Page 18 INFORMATION WG972-E4, WSM WG972-L-E4, WG972-N-E4 WG972-L-E4, WG972-N-E4 516 mm (20.3 in.) 393 mm (15.5 in.) 503 mm (19.8 in.) 9Y1211108INI0010US0 I-14 KiSC issued 07, 2015 A...

  • Page 19: Wiring Diagram

    INFORMATION WG972-E4, WSM 6. WIRING DIAGRAM WG972-GL-E4 I-15 KiSC issued 07, 2015 A...
  • Page 20 INFORMATION WG972-E4, WSM I-16 KiSC issued 07, 2015 A...
  • Page 21 INFORMATION WG972-E4, WSM WG972-G-E4 I-17 KiSC issued 07, 2015 A...
  • Page 22 INFORMATION WG972-E4, WSM I-18 KiSC issued 07, 2015 A...
  • Page 23 INFORMATION WG972-E4, WSM WG972-L-E4, WG972-N-E4 I-19 KiSC issued 07, 2015 A...
  • Page 24 INFORMATION WG972-E4, WSM I-20 KiSC issued 07, 2015 A...
  • Page 25 GENERAL KiSC issued 07, 2015 A...
  • Page 26 GENERAL CONTENTS 1. ENGINE IDENTIFICATION ......................G-1 [1] ENGINE MODEL NAME, CODE NUMBER AND ENGINE SERIAL NUMBER ...... G-1 [2] TAMPER RESISTANCE......................G-3 [3] E4 ENGINE ..........................G-3 [4] CYLINDER NUMBER ......................G-3 [5] CATALYTIC MUFFLER / CONVERTER ................G-4 2.

  • Page 27: Engine Identification

    GENERAL WG972-E4, WSM 1. ENGINE IDENTIFICATION [1] ENGINE MODEL NAME, CODE NUMBER AND ENGINE SERIAL NUMBER When contacting the manufacture, always specify your engine model name, code number and serial number. They are necessary to be identified before the engine can be serviced or parts replaced.
  • Page 28 GENERAL WG972-E4, WSM (Continued) Month of manufacture Month Engine Lot Number January A0001 ~ A9999 B0001 ~ BZ999 February C0001 ~ C9999 D0001 ~ DZ999 March E0001 ~ E9999 F0001 ~ FZ999 April G0001 ~ G9999 H0001 ~ HZ999 J0001 ~ J9999...

  • Page 29: Tamper Resistance

    GENERAL WG972-E4, WSM [2] TAMPER RESISTANCE Any modifications to the tamper resistance parts on this engine will cause this engine to be in noncompliance with emission regulations. 9Y1211108GEG0056US0 [3] E4 ENGINE [Example: Engine Model Name WG972-GL-E4-XXXX] The emission controls previously implemented in various countries to prevent air pollution will be stepped up as Non-Road Emission Standards continue to change.

  • Page 30: Catalytic Muffler / Converter

    IMPORTANT • To trace of the catalytic muffler/converter, put down the catalyst identification and engine identification when new service catalytic muffler/converter is installed. • The WG972-E4 engine must use the below catalytic parts. Genuin Part Part No. CATALYTIC MUFFLER EG821-1211-##...

  • Page 31: General Precautions

    GENERAL WG972-E4, WSM 2. GENERAL PRECAUTIONS • When you disassemble, carefully put the parts in a clean area to make it easy to find the parts. You must install the screws, bolts and nuts in their initial position to prevent the reassembly errors.

  • Page 32: Maintenance Check List

    GENERAL WG972-E4, WSM 3. MAINTENANCE CHECK LIST In order to keep your engine in good working conditions, be sure to follow the maintenance / checking schedule given in the table below. (The schedule applies to an engine in use under normal conditions.)
  • Page 33 GENERAL WG972-E4, WSM (Continued) [WG972-GL-E4] Service Interval Every Every Every Item Every Every Every Every Every 8 hrs 50 hrs after 100 hrs 200 hrs 1000 hrs 1 year 2 years (Daily) (Weekly) 1000 hrs Replacing intake hoses and clamp bands ...
  • Page 34 GENERAL WG972-E4, WSM In order to keep your engine in good working conditions, be sure to follow the maintenance / checking schedule given in the table below. (The schedule applies to an engine in use under normal conditions.) [WG972-G-E4] Service Interval...
  • Page 35 GENERAL WG972-E4, WSM In order to keep your engine in good working conditions, be sure to follow the maintenance / checking schedule given in the table below. (The schedule applies to an engine in use under normal conditions.) [WG972-L-E4, WG972-N-E4]...
  • Page 36 GENERAL WG972-E4, WSM (Continued) Change engine oil and replace oil filter cartridge after the first 50 hours of operation. *1 This is not necessary to keep the emission related warranty valid. To ensure the best quality and reliability, use new KUBOTA Genuine parts or their equivalents for repair and replacement, whenever you have maintenance done.

  • Page 37: Check And Maintenance

    GENERAL WG972-E4, WSM 4. CHECK AND MAINTENANCE [1] DAILY CHECK POINTS Checking Engine Oil Level 1. Check the engine oil level before starting or more than 5 minutes after stopping the engine. 2. To check the oil level, draw out the dipstick (1), wipe it clean, reinsert it, and draw it out again.
  • Page 38 GENERAL WG972-E4, WSM Checking and Filling Radiator Coolant 1. Without recovery tank: Remove the radiator cap (1) and check to see that the coolant level is just below the port. With recovery tank (2): Check to see that the coolant level lies between FULL "A" and LOW "B".

  • Page 39: Check Points Of Initial 50 Hours

    GENERAL WG972-E4, WSM Checking Fuel Tank Setting Condition (Gas Line) (If Necessary) [WG972-GL, WG972-L, WG972-N] 1. Check that LPG or CNG fuel tank is installed firmly. 2. Be sure that the fill up valve and liquid withdrawal valve of the LPG or CNG fuel tank can be opened and closed easily.

  • Page 40: Check Points Of Every 50 Hours

    GENERAL WG972-E4, WSM Replacing Oil Filter Cartridge CAUTION • Be sure to stop the engine before replacing oil filter cartridge. • Allow engine to cool down sufficiently, oil can be hot and cause burns. 1. Remove the oil filter cartridge (1) with the filter wrench.
  • Page 41 GENERAL WG972-E4, WSM CAUTION • Stop the engine before checking or replacing the fuel pipes. Broken fuel pipes can cause fires. • Make sure to check the fuel line periodically. The fuel line is subject to wear and aging, fuel may leak out onto the operating engine, causing a fire.

  • Page 42: Check Points Of Every 100 Hours

    GENERAL WG972-E4, WSM [4] CHECK POINTS OF EVERY 100 HOURS Cleaning Spark Plug (If Necessary) 1. Remove the spark plug, and remove carbon from the electrode with a wire brush or other tools. 2. After cleaning, be sure to adjust for proper clearance.
  • Page 43 GENERAL WG972-E4, WSM Replacing Fuel Filter (Gasoline Line) Necessary) [WG972-GL, WG972-G] 1. Loosen clamps and remove the fuel hoses. 2. Replace the fuel filter with the new one. CAUTION • Stop the engine when trying to check and clean the fuel filter.

  • Page 44: Check Points Of Every 200 Hours

    GENERAL WG972-E4, WSM [5] CHECK POINTS OF EVERY 200 HOURS Replacing Engine Oil CAUTION • Be sure to stop engine before replacing engine oil. 1. Start and warm up the engine for approx. 5 minutes. 2. Place an oil pan underneath the engine.
  • Page 45 GENERAL WG972-E4, WSM Checking Fuel Tank Setting Condition (Gas Line) [WG972-GL, WG972-L, WG972-N] 1. Check that LPG or CNG fuel tank is installed firmly. 2. Be sure that the fill up valve and liquid withdrawal valve of the LPG or CNG fuel tank can be opened and closed easily.
  • Page 46 GENERAL WG972-E4, WSM Checking Battery Specific Gravity CAUTION • If battery acid (dilute sulfuric acid) gets on you it could cause blindness or burns, or could cause corrosion of machinery and tools so please be careful when handling. • Wear safety glasses and rubber gloves when performing battery maintenance and inspection (measuring specific gravity, filling water, or charging).

  • Page 47: Check Points Of Every 1000 Hours

    GENERAL WG972-E4, WSM Checking Radiator Hoses and Clamp Bands 1. Check to see if the radiator hoses are properly fixed every 200 hours of operation or every six months, whichever comes first. 2. If the clamp is loose, apply oil to the threads and retighten it securely.
  • Page 48 GENERAL WG972-E4, WSM Checking Valve Clearance IMPORTANT • The valve clearance must be checked and adjusted when engine is cold. 1. Remove the cylinder head cover and the spark plugs. 2. Align the "1TC" mark (1) on the flywheel and alignment mark (2) on the rear end plate so that the No.

  • Page 49: Check Points Of Every After 1000 Hours

    GENERAL WG972-E4, WSM [7] CHECK POINTS OF EVERY AFTER 1000 HOURS Cleaning Combustion Chamber (If Necessary) 1. Remove the breather hose. 2. Remove the head cover screws. 3. Remove the cylinder head cover. 4. Remove the screws of the rocker arm bracket.

  • Page 50: Check Points Of Every 1 Year

    GENERAL WG972-E4, WSM [8] CHECK POINTS OF EVERY 1 YEAR Replacing Air Cleaner Primary and Secondary Element 1. Remove the cover (2) from the air cleaner. 2. After cleaning the cover (2), remove the used air cleaner primary (4) and secondary (3) element.
  • Page 51 GENERAL WG972-E4, WSM Cleaning Radiator and Water Jacket CAUTION • Do not stop the engine suddenly, stop it after about 5 minutes ofunloaded idling. • Work only after letting the engine and radiator cool off completely (more than 30 minutes after it has been stopped).

  • Page 52: Check Points Of Every 2 Years

    GENERAL WG972-E4, WSM Anti-Freeze • There are two types of anti-freeze available: use the permanent type (PT) for this engine. • Before adding anti-freeze for the first time, clean the radiator interior by pouring fresh, soft water and draining it a few times.
  • Page 53 GENERAL WG972-E4, WSM Replacing Breather Hose [WG972-GL, WG972-L, WG972-N] 1. Replace the breather hoses (1) and the clamps between the head cover and the gas mixer, and between the head cover and intake manifold. (1) Breather Hose 9Y1211108GEG0046US0 Replacing Breather Hose [WG972-G] 1.
  • Page 54 GENERAL WG972-E4, WSM Replacing Battery CAUTION • When the battery is being activated, hydrogen and oxygen gases in the battery are extremely explosive. Keep open sparks and flames away from the battery at all times, especially when charging the battery.
  • Page 55 GENERAL WG972-E4, WSM (Continued) (Anti-freeze) • There are two types of anti-freeze available; use the permanent type (PT) for this engine. • Before adding anti-freeze for the first time, clean the radiator interior by pouring fresh, soft water and drain it a few times.

  • Page 56: Special Tools

    GENERAL WG972-E4, WSM 5. SPECIAL TOOLS Compression Tester Code No. • 07909-30251 Application • Use to measure gasoline engine compression and diagnose the engine for a major overhaul. 9Y1211108GEG0008US0 Oil Pressure Tester Code No. • 07916-32032 Application • Use to measure lubricating oil pressure.
  • Page 57 GENERAL WG972-E4, WSM Bushing Replacing Tool Application • Use to press out and to press fit the bushing. [For small end bushing] 145 mm (5.71 in.) 20 mm (0.79 in.) 100 mm (3.94 in.) 19.90 to 19.95 mm dia. (0.7835 to 0.7854 in. dia.) 21.90 to 21.95 mm dia.
  • Page 58 GENERAL WG972-E4, WSM Crankshaft Bearing 1 Replacing Tool Application • Use to press out and press fit the crankshaft bearing 1. [Press Out] 135 mm (5.31 in.) 72 mm (2.8 in.) 40 mm radius (1.6 in. radius) 10 mm (0.39 in.) 22 mm (0.87 in.)
  • Page 59 ENGINE KiSC issued 07, 2015 A...
  • Page 60 MECHANISM CONTENTS 1. ENGINE BODY........................... 1-M1 [1] CYLINDER BLOCK ......................1-M1 [2] HALF-FLOATING HEAD COVER ..................1-M1 [3] CYLINDER HEAD ........................ 1-M2 [4] CRANKSHAFT ........................1-M2 [5] PISTON AND PISTON RING ....................1-M3 [6] OIL PAN ..........................1-M3 [7] CONNECTING ROD ......................1-M4 [8] CAMSHAFT..........................
  • Page 61 [7] CAMSHAFT POSITION SENSOR..................1-M28 [8] IGNITION COIL ........................1-M29 KiSC issued 07, 2015 A...

  • Page 62: Engine Body

    ENGINE WG972-E4, WSM 1. ENGINE BODY [1] CYLINDER BLOCK The engine has a high durability tunnel-type cylinder block in which the crank bearing component is a constructed body. Furthermore, liner less type, allow effective cooling, less distortion, and greater wear resistance.

  • Page 63: Cylinder Head

    ENGINE WG972-E4, WSM [3] CYLINDER HEAD Intake and Exhaust Port The cross-flow type intake / exhaust ports, which lower the heat conduction from the exhaust port to the intake port. The low heat conduction keeps the intake air from being heated and expanded by the exhaust gas.

  • Page 64: Piston And Piston Ring

    ENGINE WG972-E4, WSM [5] PISTON AND PISTON RING Piston and Piston Ring The piston head has the combustion chamber (1) with the concave of bathtub shaped type. Top Ring: Barrel-faced type has an ideal shape in terms of lubrication theory in order to prevent abnormal wear due to edge loading at the time of initial running-in, and it is very effective in prevention of blow-by.

  • Page 65: Connecting Rod

    ENGINE WG972-E4, WSM [7] CONNECTING ROD The connecting rod (2) is used to connect the piston with the crankshaft. The big end of the connecting rod has a crankpin bearing (3) (split type) and the small end has a small end bushing (1) (solid type).

  • Page 66: Inlet And Exhaust Valves

    ENGINE WG972-E4, WSM [10] INLET AND EXHAUST VALVES The valve and its guide for the inlet are different from those for the exhaust. Other parts, such as the spring (4), spring retainer (3), collet (2), stem seal (5), and cap (1) are the same for both the inlet and exhaust.

  • Page 67: Lubricating System

    ENGINE WG972-E4, WSM 2. LUBRICATING SYSTEM [1] GENERAL (A) Piston (C) Camshaft (E) Oil Strainer (F) Oil Pump (B) Rocker Arm and Rocker (D) Oil Filter Cartridge and Arm Shaft Relief Valve The lubricating system consists of an oil strainer, an oil pump, a relief valve, an oil filter cartridge and an oil pressure switch.

  • Page 68: Oil Pump

    ENGINE WG972-E4, WSM [2] OIL PUMP The oil pump is a trochoid pump, whose rotors have trochoid lobes. The inner rotor (2) has 4 lobes and the outer rotor (4) has 5 lobes, and they are eccentrically engaged with each other. The inner rotor, which is driven...

  • Page 69: Oil Pressure Switch

    ENGINE WG972-E4, WSM [5] OIL PRESSURE SWITCH The oil pressure switch is mounted on the cylinder block and is led to the lubricating oil passage. When the oil pressure falls below the specified value, the oil pressure warning lamp lights.

  • Page 70: Cooling System

    ENGINE WG972-E4, WSM 3. COOLING SYSTEM [1] GENERAL The cooling system consists of a radiator (1), a centrifugal water pump (4), a suction fan (2) and a thermostat (3). The coolant is cooled through the radiator core, and the fan behind the radiator pulls the cooling air through the core to improve cooling.

  • Page 71: Thermostat

    ENGINE WG972-E4, WSM [4] THERMOSTAT The thermostat is of the wax pellet type. The thermostat controls the flow of the coolant to the radiator to keep the proper temperature. The case, which serves as a valve seat, has a spindle inserted in the pellet (3) which is installed to the valve (2).

  • Page 72: Radiator Cap

    ENGINE WG972-E4, WSM [6] RADIATOR CAP The pressure type radiator cap prevents differences in pressure between the inside and the outside of the radiator from deforming the radiator. When the coolant temperature rises and the pressure in the radiator increases above the specified pressure, the pressure valve (1) opens to reduce the internal pressure.

  • Page 73: Fuel System

    ENGINE WG972-E4, WSM 4. FUEL SYSTEM [1] GENERAL Gasoline Fuel System [WG972-GL, WG972-G] (1) Fuel Rail (3) Fuel Filter* (A) Gasoline line (B) Bleed / Return circuit (If (2) Fuel Pump Assembly* (4) Gasoline Tank* necessary) NOTE • The *-marked component parts are Not Provided by KUBOTA.
  • Page 74 ENGINE WG972-E4, WSM Gaseous Fuel System [WG972-GL, WG972-L, WG972-N] (1) Gas Regulator with Vaporizer* (5) LPG Line [WG972-GL, (8) LPG Tank (with Manual (A) Hot Water OUT (2) Lock Off Valve* WG972-L] Valve)* (B) Hot Water IN (3) Balance Line*...

  • Page 75: Fuel Filter (Gasoline Line) [Wg972-Gl, Wg972-G]

    ENGINE WG972-E4, WSM [2] FUEL FILTER (GASOLINE LINE) [WG972-GL, WG972-G] The fuel filter is installed in the fuel line between the fuel tank and the feed pump. As the fuel flows from the inlet "A" through the filter element (1), the dirt and impurities in the fuel are filtered, allowing only clean fuel to penetrate the inside of the filter element.

  • Page 76: Fuel Pump (Gasoline Line) [Wg972-Gl, Wg972-G]

    ENGINE WG972-E4, WSM [3] FUEL PUMP (GASOLINE LINE) [WG972-GL, WG972-G] The gasoline system will use an external electric gasoline fuel pump. The pump will be mounted in the chassis of the vehicle, or equipment near the fuel tank. Gasoline rated fuel hose and securing devices supplied by the OEM, will be used to transfer the pumped fuel to the fuel rail.

  • Page 77: Lock Off Valve (Gas Line) [Wg972-Gl, Wg972-L, Wg972-N]

    ENGINE WG972-E4, WSM [6] LOCK OFF VALVE (GAS LINE) [WG972-GL, WG972-L, WG972-N] The lock off valve blocks off liquid fuel flow to regulator by solenoid. Lock off valve has fuel filter and liquid fuel comes to lock off valve after passing through the filter.

  • Page 78: Regulator With Vaporizer (Gas Line) [Wg972-Gl, Wg972-L, Wg972-N]

    ENGINE WG972-E4, WSM [7] REGULATOR WITH VAPORIZER (GAS LINE) [WG972-GL, WG972-L, WG972-N] Regulator with vaporizer evaporates the liquid fuel (LPG / CNG) into the gaseous fuel and then sends to the mixer. Regulator with vaporizer has the following structures and functions.
  • Page 79 ENGINE WG972-E4, WSM Evaporator Liquid fuel comes to regulator from lock off valve, and then comes into evaporator (1) through primary valve. Evaporator (1) has a long fuel passage and liquid fuel evaporates to gaseous fuel while passing through this long passage.
  • Page 80 ENGINE WG972-E4, WSM Primary Stage Primary valve is pulled by primary valve spring at normal condition and primary valve opens inlet of liquid fuel. Gaseous fuel fills in primary chamber and gas pressure does not push down primary valve spring in normal condition.

  • Page 81: Mixer (Gas Line) [Wg972-Gl, Wg972-L, Wg972-N]

    ENGINE WG972-E4, WSM [8] MIXER (GAS LINE) [WG972-GL, WG972-L, WG972-N] Mixer (3) is a device to mix air and gaseous fuel with proper ratio required by the engine. The gaseous LPG or CNG fuel flows to the mixer through main jet (1) from the Regulator with vaporizer.

  • Page 82: Exhaust System

    ENGINE WG972-E4, WSM 5. EXHAUST SYSTEM [1] THREE-WAY CATALYST A three-way catalyst is a catalyst that removes CO, HC and NOx at the same time by oxidation-reduction reaction. A three-way catalyst oxidizes HC to CO and H and also CO to CO...

  • Page 83: Oxygen Sensor

    ENGINE WG972-E4, WSM [2] OXYGEN SENSOR An Oxygen sensor is an essential element of a feedback control of air-fuel ratio. The sensor has a zirconia tube which is a solid electrolyte. The outside of zirconia tube contacts with the exhaust gas and the inside of zirconia tube contacts with the atmosphere to know each oxygen concentration.

  • Page 84: Electrical System

    ENGINE WG972-E4, WSM 6. ELECTRICAL SYSTEM [1] STARTING SYSTEM Starter The starter is the electromagnetic drive type. DC, Series-wound, Electromagnetic Type of motor drive Nominal output 12 V Nominal output 1.0 kW 30 seconds (Do not rotate Nominal output continuously for longer periods.)

  • Page 85: Charging System

    ENGINE WG972-E4, WSM Key Switch The key switch has 4 positions. The terminal "30" is connected to the battery. It is released at the "START" position and returns to the "ON" position. [START] When the key is turned to the "START" position, through the "ON"...
  • Page 86 ENGINE WG972-E4, WSM D2 Type Regulator (1) Alternator Assembly (2) IC Regulator (3) Key Switch IC regulator has a special feature that makes it possible to interrupt field current by using the transistor or IC instead of the contact-point-type regulator.
  • Page 87 ENGINE WG972-E4, WSM Total Wave Rectification In case of the generator for mobile equipment of which purpose is to charge the batteries, alternating current cannot be used as it is. Because of this, it is required to conduct the action called rectification so that the alternating current can be changed to direct current.

  • Page 88: Engine Control Unit (Ecu)

    ENGINE WG972-E4, WSM Surge voltage waveform with any charging cable disconnection. • May be VHmin = 6.5 V in high electric load shedding or unloaded condition with the battery fully charged. (1) Voltage (a) VH max (2) Angle of Rotation (°)

  • Page 89: Temperature And Manifold Absolute Pressure Sensor (Tmap Sensor)

    ENGINE WG972-E4, WSM [5] TEMPERATURE AND MANIFOLD ABSOLUTE PRESSURE SENSOR (TMAP SENSOR) TMAP sensor is mounted in the intake manifold and measures the absolute pressure as well as the temperature of the air / fuel stream. MAP data is used by...
  • Page 90 ENGINE WG972-E4, WSM [8] IGNITION COIL Ignition coil is a transformer to generate high electric voltage necessary for the ignition. Around the iron core of multi-layer thin crude steel plates, secondary coil is wound, on whose outside, in the same direction, primary coil is wound.
  • Page 91 SERVICING CONTENTS 1. TROUBLESHOOTING.........................1-S1 [1] FOR GENERAL ........................1-S1 [2] FOR GASOLINE FUEL [WG972-GL, WG972-G] ..............1-S5 [3] FOR GAS FUEL [WG972-GL, WG972-L, WG972-N]............1-S5 2. SERVICING SPECIFICATIONS ....................1-S6 3. TIGHTENING TORQUES......................1-S12 [1] TIGHTENING TORQUES FOR GENERAL USE SCREWS, BOLTS AND NUTS....1-S12 [2] TIGHTENING TORQUES FOR SPECIAL USE SCREWS, BOLTS AND NUTS....1-S13 4.

  • Page 92: Troubleshooting

    ENGINE WG972-E4, WSM 1. TROUBLESHOOTING [1] FOR GENERAL Probable Cause and Reference Symptom Solution Checking Procedure Page Engine Does Not Turn 1. Seizure of crankshaft, Check if crankshaft rotates – Over piston, etc. Repair or replace 1-S33, 1-S36 2. Battery discharged Charge –...
  • Page 93 ENGINE WG972-E4, WSM Probable Cause and Reference Symptom Solution Checking Procedure Page Deficient Output 1. Fuel is insufficient Check the fuel system – 2. Damaged spark plug Check and adjust or replace 1-S20, 1-S21 3. Damaged ignition coil Check and replace 1-S21 4.
  • Page 94 ENGINE WG972-E4, WSM Probable Cause and Reference Symptom Solution Checking Procedure Page Rough High-speed 1. Damaged spark plug Check and adjust or replace 1-S20, Operating 1-S21 2. Damaged ignition coil Check and replace 1-S21 3. Wires disconnection or Check the wire harness –...
  • Page 95 ENGINE WG972-E4, WSM Probable Cause and Reference Symptom Solution Checking Procedure Page Lubricant Oil 1. Oil leakage from oil seal, Replace – Consumption Is gasket, etc. Excessive 2. Damaged valve stem seal Replace 1-S29 3. Piston ring and liner worn...

  • Page 96: For Gasoline Fuel [Wg972-Gl, Wg972-G]

    ENGINE WG972-E4, WSM [2] FOR GASOLINE FUEL [WG972-GL, WG972-G] Probable Cause and Reference Symptom Solution Checking Procedure Page Engine Turns Over At 1. Spark plug electrodes are Dry electrode and restart – Normal Speed But wet with gasoline Does Not Start...

  • Page 97: Servicing Specifications

    ENGINE WG972-E4, WSM 2. SERVICING SPECIFICATIONS ENGINE BODY Item Factory Specification Allowable Limit Valve Clearance (Cold) 0.145 to 0.185 mm – 0.00571 to 0.00728 in. Compression Pressure – 1.27 MPa 0.88 MPa 13.0 kgf/cm 9.0 kgf/cm 185 psi 130 psi Variance Among –...
  • Page 98 ENGINE WG972-E4, WSM Item Factory Specification Allowable Limit Valve Spring Free Length 31.3 to 31.8 mm 28.4 mm 1.24 to 1.25 in. 1.12 in. Tilt – 1.2 mm 0.047 in. Setting Load / 65 N / 27.0 mm 55 N / 27.0 mm Setting Length 6.6 kgf / 27.0 mm...
  • Page 99 ENGINE WG972-E4, WSM Item Factory Specification Allowable Limit Idle Gear Shaft to Idle Gear Bushing Oil Clearance 0.020 to 0.088 mm 0.10 mm 0.00079 to 0.0035 in. 0.0039 in. • Idle Gear Shaft O.D. 19.967 to 19.980 mm – 0.78611 to 0.78661 in.
  • Page 100 ENGINE WG972-E4, WSM Item Factory Specification Allowable Limit Crankpin to Crankpin Bearing Oil Clearance 0.020 to 0.051 mm 0.15 mm 0.00079 to 0.0020 in. 0.0059 in. • Crankpin O.D. 33.959 to 33.975 mm – 1.3370 to 1.3375 in. • Crankpin Bearing I.D.
  • Page 101 ENGINE WG972-E4, WSM LUBRICATING SYSTEM Item Factory Specification Allowable Limit Engine Oil Pressure At Idle Speed More than 50 kPa – 0.5 kgf/cm 7 psi At Rated Speed 200 to 440 kPa 150 kPa 2.0 to 4.5 kgf/cm 1.5 kgf/cm...
  • Page 102 ENGINE WG972-E4, WSM Item Factory Specification Allowable Limit Crankshaft Position Sensor Resistance 1.85 to 2.45 kΩ – at 20 °C (68 °F) Camshaft Position Sensor Conduction of Not conduction each pins (Check with communication ECU) Spark Plug Plug Gap 0.70 to 0.80 mm –...

  • Page 103: Tightening Torques

    ENGINE WG972-E4, WSM 3. TIGHTENING TORQUES Screws, bolts and nuts must be tightened to the specified torque using a torque wrench, several screws, bolts and nuts such as those used on the cylinder head must be tightened in proper sequence and the proper torque.

  • Page 104: Tightening Torques For Special Use Screws, Bolts And Nuts

    ENGINE WG972-E4, WSM [2] TIGHTENING TORQUES FOR SPECIAL USE SCREWS, BOLTS AND NUTS NOTE • For "*" marked screws, bolts and nuts on the table, apply engine oil to their threads and seats before tightening. • The letter "M" in Size means that the screw, bolt or nut dimension stands for metric. The size is the nominal outside diameter in mm of the threads.

  • Page 105: Checking, Disassembling And Servicing

    ENGINE WG972-E4, WSM 4. CHECKING, DISASSEMBLING AND SERVICING [1] CHECKING AND ADJUSTING (1) Engine Body Compression Pressure 1. Operate the engine until it is warmed up. 2. Stop the engine. 3. Remove the air cleaner, the muffler/converter and all spark plugs.
  • Page 106 ENGINE WG972-E4, WSM Adjusting the Valve Clearance IMPORTANT • The valve clearance must be checked and adjusted when engine is cold. 1. Remove the cylinder head cover and the spark plugs. 2. Align the "1TC" mark (1) on the flywheel and alignment mark (2) on the rear end plate so that the No.

  • Page 107: Lubricating System

    ENGINE WG972-E4, WSM (2) Lubricating System Engine Oil Pressure 1. Remove the engine oil pressure switch, and set an oil pressure tester. 2. Start the engine. After warming up, measure the oil pressure of both idling and rated speeds. 3. If the oil pressure is less than the allowable limit, check the following.

  • Page 108: Cooling System

    ENGINE WG972-E4, WSM (3) Cooling System Fan Belt Tension 1. Measure the deflection (A), depressing the belt halfway between the fan drive pulley and alternator pulley at specified force 98 N (10 kgf, 22 lbf). 2. If the measurement is not within the factory specifications, loosen the alternator mounting screws and relocate the alternator to adjust.

  • Page 109: Fuel System

    ENGINE WG972-E4, WSM CAUTION • When removing the radiator cap, wait at least ten minutes after the engine has stopped and cooled down. Otherwise, hot water may gush out, scalding nearby people. 9Y1211108ENS0013US0 Radiator Cap Air Leakage 1. Set a radiator tester (1) and an adaptor (2) on the radiator cap.

  • Page 110: Ignition System

    ENGINE WG972-E4, WSM Resistance of Injector (Gasoline line) [WG972-GL, WG972-G] 1. Disconnect the connector. 2. Measure the resistance between terminals with an ohmmeter. 3. If the resistance is not with in the factory specifications, replace 11.7 to 12.3 Ω Resistance Factory specification at 20 °C (68 °F)
  • Page 111 ENGINE WG972-E4, WSM Spark Test 1. Disconnect all injector connector. 2. Remove the spark plug, put it inside the ignition coil firmly, and then ground the threaded section to the engine body (not to painted or resin parts). 3. Rotate the starter with the key switch and check that the plug sparks.

  • Page 112: Electrical System

    ENGINE WG972-E4, WSM Spark Plug Gap 1. Measure the spark plug gap with a feeler gauge, and repair or replace the spark plug if the measured gap differs from the factory specification. 2. Replace the spark plug if the electrode or the insulator is deformed or cracked.
  • Page 113 ENGINE WG972-E4, WSM Battery Specific Gravity 1. Measure the specific gravity of the electrolyte in each cell with a battery and coolant tester. 2. If the electrolyte temperature is different from the one that the battery and coolant tester calibrated, correct the specific gravity measurement.
  • Page 114 ENGINE WG972-E4, WSM Magnetic Switch Test 1. Disconnect the battery negative cable from the battery. 2. Disconnect the battery positive cable from the battery. 3. Disconnect the leads from the starter B terminal. 4. Remove the starter from the engine.
  • Page 115 ENGINE WG972-E4, WSM Alternator on Unit Test (Before testing) • Before alternator on unit test, check the battery terminal connections, circuit connection, fan belt tension, charging indicator lamp, fuses on the circuit, and abnormal noise from the alternator. • Prepare full charged battery for the test.

  • Page 116: Disassembling And Assembling

    ENGINE WG972-E4, WSM [2] DISASSEMBLING AND ASSEMBLING IMPORTANT • When reassembling, replace all of the O-rings and gaskets by new ones. • When disassembling the LPG engine after completely consuming the fuel in piping. 9Y1211108ENS0034US0 (1) Draining Coolant and Engine Oil Draining Engine Oil 1.

  • Page 117: External Components

    ENGINE WG972-E4, WSM (2) External Components Alternator, Starter and Others 1. Remove the wiring harness (1). 2. Remove the air cleaner, catalytic muffler/converter and exhaust manifold (4). 3. Remove the cooling fan (2), fan pulley and fan belt (3). 4. Remove the alternator (5).

  • Page 118: Cylinder Head, Valves And Oil Pan

    ENGINE WG972-E4, WSM Ignition Coil and Spark Plug 1. Remove the ignition coil (1). 2. Remove the intake manifold assembly (2). 3. Remove the spark plug (3). (When reassembling) • Tighten the spark plug with a plug wrench. IMPORTANT • Put the ignition coil inside the spark plug terminal firmly.
  • Page 119 ENGINE WG972-E4, WSM Cylinder Head 1. Loosen the pipe clamps (2), and remove the water return hose (1). 2. Remove the cylinder head screw in the order of (n) to (a). 3. Lift up the cylinder head to remove. 4. Remove the cylinder head gasket.
  • Page 120 ENGINE WG972-E4, WSM Valves 1. Remove the valve caps (2). 2. Remove the valve spring collet (3), pushing the valve spring retainer (4) with valve spring replacer (1). 3. Remove the valve spring retainer (4), valve spring (5) and valve stem seal (6).
  • Page 121 ENGINE WG972-E4, WSM Oil Pan and Oil Strainer 1. Remove the oil pan mounting screws (2). 2. Remove the oil pan (1) by lightly tapping the rim of the pan with a wooden hammer. 3. Remove the oil strainer (3).

  • Page 122: Thermostat

    ENGINE WG972-E4, WSM (4) Thermostat Thermostat Assembly 1. Remove the thermostat cover mounting screws (1), and remove the thermostat cover (2). 2. Remove the thermostat assembly (4). (When reassembling) • Apply a liquid gasket (Three Bond 1215 or equivalent) only at the thermostat cover side of the gasket (3).
  • Page 123 ENGINE WG972-E4, WSM Idle Gear 1. Remove the external snap ring (1), the collar (3) and the idle gear (2). 2. Remove the idle gear shaft mounting screws (4). 3. Remove the idle gear shaft (5). (When reassembling) • Apply engine oil to the idle gear shaft mounting screw (4). And tighten them.

  • Page 124: Piston And Connecting Rod

    ENGINE WG972-E4, WSM (6) Piston and Connecting Rod Connecting Rod Cap 1. Remove the connecting rod caps (1) using a hexagonal 7 mm socket. (When reassembling) • Align the marks (a) with each other. (Face the marks toward the intake manifold.) •...

  • Page 125: Crankshaft

    ENGINE WG972-E4, WSM Piston Ring and Connecting Rod 1. Remove the piston rings using a piston ring tool. 2. Remove the piston pin (10), and separate the connecting rod (8) from the piston (7). (When reassembling) • When installing the second compression ring (2), assemble the rings so that the manufacturer's mark (11) near the gap faces the top of the piston.
  • Page 126 ENGINE WG972-E4, WSM Bearing Case Cover 1. Remove the bearing case cover mounting screws. First, remove inside screws (1) and then outside screws (2). 2. Remove the bearing case cover (6). (When reassembling) • Fit the bearing case gasket (3) and the bearing case cover gasket (4) with correct directions.
  • Page 127 ENGINE WG972-E4, WSM Crankshaft Assembly 1. Remove the main bearing case screw 2 (1). 2. Turn the crankshaft to set the crankpin of the third cylinder to the bottom dead center. Then draw out the crankshaft until the crankpin of the second cylinder comes to the center of the third cylinder.
  • Page 128 ENGINE WG972-E4, WSM Main Bearing Case Assembly 1. Remove the two main bearing case screws 1 (4), and remove the main bearing case assembly 1 (1), being careful with crankshaft bearing 3 (5), (9). 2. Remove the main bearing case assembly 2 (2) and the main bearing case assembly (3) as above.

  • Page 129: Starter

    ENGINE WG972-E4, WSM (8) Starter (1) Solenoid Switch Mounting (2) Starter Drive Housing (3) Drive Lever (4) Gasket (5) Solenoid Switch (6) B Terminal Nut (7) C Terminal Nut (8) Snap Ring (9) Overrunning Clutch (10) Armature (11) Brush Spring...

  • Page 130: Alternator

    ENGINE WG972-E4, WSM (9) Alternator (1) Pulley (2) Drive End Frame (3) Stator (4) Bearing (5) Retainer Plate (6) Rotor (7) Bearing (8) Rear End Frame (9) Rectifier (10) IC Regulator (11) Brush Holder (12) Rear End Cover 1. Remove the pulley (1).

  • Page 131: Servicing

    ENGINE WG972-E4, WSM [3] SERVICING (1) Combustion Chamber Cleaning Combustion Chamber Clean any carbon deposits from the combustion chamber walls including the cylinder head surface, surroundings of valve tops, and piston top surfaces. Check valve seating according to following section, and do valve seat grinding if necessary.

  • Page 132: Cylinder Head And Valves

    ENGINE WG972-E4, WSM (2) Cylinder Head and Valves Top Clearance 1. Remove the cylinder head. 2. With the piston at TDC, use grease to affix three or four plastigauges of a diameter 1.5 mm (0.059 in.) × 5.0 to 7.0 mm (0.20 to 0.27 in.) long to the crown of the piston;...
  • Page 133 ENGINE WG972-E4, WSM Valve Recessing 1. Clean the cylinder head, the valve face and seat. 2. Insert the valve into the valve guide. 3. Measure the valve recessing with a depth gauge. 4. If the measurement exceeds the allowable limit, replace the valve.
  • Page 134 ENGINE WG972-E4, WSM Correcting Valve and Valve Seat NOTE • Before correcting the valve and seat, check the valve stem and the I.D. of valve guide section, and repair them if necessary. • After correcting the valve seat, be sure to check the valve recessing.
  • Page 135 ENGINE WG972-E4, WSM Clearance between Valve Stem and Valve Guide 1. Remove carbon from the valve guide section. 2. Measure the valve stem O.D. with an outside micrometer. 3. Measure the valve guide I.D. with a small hole gauge, and calculate the clearance.
  • Page 136 ENGINE WG972-E4, WSM Free Length and Tilt of Valve Spring 1. Measure the free length (B) of valve spring with vernier calipers. If the measurement is less than the allowable limit, replace it. 2. Put the spring on a surface plate, place a square on the side of the spring.

  • Page 137: Timing Gear And Camshaft

    ENGINE WG972-E4, WSM Push Rod Alignment 1. Place the push rod on V blocks. 2. Measure the push rod alignment. 3. If the measurement exceeds the allowable limit, replace the push rod. 0.25 mm Push rod alignment Allowable limit 0.0098 in.
  • Page 138 ENGINE WG972-E4, WSM Idle Gear Side Clearance 1. Set a dial indicator with its tip on the idle gear. 2. Measure the side clearance by moving the idle gear to the front and rear. 3. If the measurement exceeds the allowable limit, replace the idle gear collar.
  • Page 139 ENGINE WG972-E4, WSM Oil Clearance of Camshaft Journal 1. Measure the camshaft journal O.D. with an outside micrometer. 2. Measure the cylinder block bore I.D. for camshaft with a inside micrometer, and calculate the oil clearance. 3. If the clearance exceeds the allowable limit, replace the camshaft.

  • Page 140: Piston And Connecting Rod

    ENGINE WG972-E4, WSM (4) Piston and Connecting Rod Piston Pin Bore I.D. 1. Measure the piston pin bore I.D. in both the horizontal and vertical directions with a cylinder gauge. 2. If the measurement exceeds the allowable limit, replace the piston.
  • Page 141 ENGINE WG972-E4, WSM Piston Ring Gap 1. Insert the piston ring into the lower part of the cylinder (the least worn out part) with a piston ring compressor and piston. 2. Measure the ring gap with a feeler gauge. 3. If the measurement exceeds the allowable limit, replace the piston ring.
  • Page 142 ENGINE WG972-E4, WSM Clearance between Piston Ring and Piston Ring Groove 1. Clean the rings and the ring grooves, and install each ring in its groove. 2. Measure the clearance between the ring and the groove with a thickness gauge.

  • Page 143: Crankshaft

    ENGINE WG972-E4, WSM (5) Crankshaft Crankshaft Side Clearance 1. Set a dial indicator with its tip on the end of the crankshaft. 2. Measure the side clearance by moving the crankshaft to the front and rear. 3. If the measurement exceeds the allowable limit, replace the thrust bearings.
  • Page 144 ENGINE WG972-E4, WSM Oil Clearance between Crankpin and Crankpin Bearing 1. Clean the crankpin and crankpin bearing. 2. Put a strip of plastigage on the center of the crankpin. 3. Install the connecting rod cap and tighten the connecting rod screws to the specified torque, and remove the cap again.
  • Page 145 ENGINE WG972-E4, WSM Oil Clearance between Crankshaft Journal and Crankshaft Bearing 1 1. Measure the O.D. of the crankshaft front journal with an outside micrometer. 2. Measure the I.D. of the crankshaft bearing 1 with an inside micrometer, and calculate the oil clearance.
  • Page 146 ENGINE WG972-E4, WSM Oil Clearance between Crankshaft Journal and Crankshaft Bearing 2 (Crankshaft Bearing 3) 1. Put a strip of plastigage on the center of the journal. 2. Install the bearing case and tighten the bearing case screws 1 to the specified torque, and remove the bearing case again.

  • Page 147: Cylinder

    ENGINE WG972-E4, WSM (Continued) (Reference) • Undersize crankshaft bearing 2 and 3 Undersize Bearing Code Number Marking Crankshaft bearing 2 02 15694-23930 020 US Crankshaft bearing 2F 02 1G460-07530 0.2 mm 0.008 in. Crankshaft bearing 3 02 1G460-07580 020 US...

  • Page 148: Oil Pump

    ENGINE WG972-E4, WSM Correcting Cylinder (Oversize) 1. When the cylinder is worn beyond the allowable limit, bore and hone it to the specified dimension. 75.000 to 75.019 mm Factory specification 2.9528 to 2.9535 in. Cylinder liner I.D. 75.150 mm Allowable limit 2.9587 in.

  • Page 149: Starter

    ENGINE WG972-E4, WSM (8) Starter Overrunning Clutch 1. Inspect the pinion for wear or damage. 2. If there is any problem, replace the overrunning clutch assembly. 3. Check that the pinion turns freely and smoothly in the overrunning direction and does not slip in the cranking direction.
  • Page 150 ENGINE WG972-E4, WSM Brush Holder 1. Check the continuity across the brush holder and the holder support with an ohmmeter. 2. If it conducts, replace the brush holder. 9Y1211108ENS0105US0 Armature Coil 1. Check the continuity across the commutator and armature coil core with an ohmmeter.

  • Page 151: Alternator

    ENGINE WG972-E4, WSM (9) Alternator Bearing 1. Check the bearing for smooth rotation. 2. If it does not rotate smoothly, replace it. 9Y1211108ENS0108US0 Stator 1. Measure the resistance across each lead of the stator coil with resistance range of circuit tester.
  • Page 152 ENGINE WG972-E4, WSM Rectifier 1. Check the continuity across each diode of rectifier with resistance range of circuit tester. 2. The rectifier is normal if the diode in the rectifier conducts in one direction and does not conduct in the reverse direction.
  • Page 153 EDITOR : KUBOTA FARM & INDUSTRIAL MACHINERY SERVICE, LTD. 64, ISHIZU-KITAMACHI, SAKAI-KU, SAKAI-CITY, OSAKA, 590-0823, JAPAN PHONE : ( 81 ) 72-241-1129 : ( 81 ) 72-245-2484 E-mail : ks_g.ksos-pub@kubota.com Printed in Japan 2015. 07, S, EI, EI, engusa Code No.9Y111-11080 2015.

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