wsm wg972-e4 Instruction manual

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

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
• Performance Curve
• Important Items of Exhaust Emission Regulation
• Dimension
• Wiring Diagram
General
This section contains information below.
• Engine Identification
• General Precautions
• Maintenance Check List
• Check and Maintenance
• Special Tools
Mechanism
This section contains information on the structure and the function of the unit. Before you continue
with the subsequent sections, make sure that you read this section.
Servicing
This section contains information below.
• Troubleshooting
• Servicing Specifications
• Tightening Torques
• Checking, Disassembling and Servicing
All illustrations, photographs and specifications contained in this manual are of the newest
information available at the time of publication.
KUBOTA reserves the right to change all information at any time without notice.
Since this manual includes many models, information or illustrations and photographs can show
more than one model.
March, 2015
© KUBOTA Corporation 2015
KiSC issued 07, 2015 A

I INFORMATION
KiSC issued 07, 2015 A

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. DIMENSIONS ............................................................................................................................... I-12
6. WIRING DIAGRAM....................................................................................................................... I-15
INFORMATION
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-1
1. SAFETY FIRST
WSM000001INI0001US1
BEFORE YOU START SERVICE
• Read all instructions and safety instructions in this
manual and on your engine safety decals.
• Clean the work area and engine.
• Park the machine on a stable and level ground.
• Let the temperature of the engine decrease before
you start a job.
• Stop the engine, then remove the key.
• Disconnect the battery negative cable.
• Hang a "DO NOT OPERATE" tag in the operator
station.
WSM000001INI0002US0
START SAFELY
• Do not do the procedures below when you start the
engine.
– short across starter terminals
– bypass the safety start switch
• Do not make unauthorized modifications to the
engine. This can cause damage and decrease the
engine life.
WSM000001INI0003US0
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.
• It is essential that you read the instructions and safety regulations before you try to repair or use this
unit.
DANGER
• Indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.
WARNING
• Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.
CAUTION
• Indicates a potentially hazardous situation which, if not avoided, could result in minor or moderate
injury.
IMPORTANT
• Indicates that equipment or property damage could result if instructions are not followed.
NOTE
• Gives helpful information.
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-2
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.
• When 2 or more persons do servicing, make sure
that you do it safely.
• Do not touch the hot parts or parts that turn when the
engine operates.
• Do not remove the radiator cap when the engine
operates, or immediately after it stops. If not, hot
water can spout out from the radiator. Only remove
the radiator cap when it is at a sufficiently low
temperature to touch with bare hands. Slowly loosen
the cap to release the pressure before you remove it
fully.
• Released fluid (fuel or hydraulic oil) under pressure
can cause damage to the skin and cause serious
injury. Release the pressure before you disconnect
hydraulic or fuel lines. Tighten all connections before
you apply the pressure.
• Do not open a fuel system under high pressure.
The fluid under high pressure that stays in fuel lines
can cause serious injury. Do not disconnect or repair
the fuel lines, sensors, or any other components
between the fuel pump and injectors on engines with
a common rail fuel system under high pressure.
• Put on an applicable ear protective device (earmuffs
or earplugs) to prevent injury against loud noises.
• Be careful about electric shock. The engine
generates a high voltage of more than DC100 V in
the ECU and is applied to the injector.
WSM000001INI0004US0
PREVENT A FIRE
• Fuel is very flammable and explosive under some
conditions. Do not smoke or let flames or sparks in
your work area.
• To prevent sparks from an accidental short circuit,
always disconnect the battery negative cable first
and connect it last.
• The battery gas can cause an explosion. Keep the
sparks and open flame away from the top of battery,
especially when you charge the battery.
• Make sure that you do not spill fuel on the engine.
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KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-3
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.
WSM000001INI0006US0
DISCARD FLUIDS CORRECTLY
• Do not discard fluids on the ground, down the drain,
into a stream, pond, or lake. Obey related
environmental protection regulations when you
discard oil, fuel, coolant, electrolyte and other
dangerous waste.
WSM000001INI0007US0
PREVENT ACID BURNS
• Keep electrolyte away from your eyes, hands and
clothing. Sulfuric acid in battery electrolyte is
poisonous and it can burn your skin and clothing and
cause blindness. If you spill electrolyte on yourself,
clean yourself with water, and get medical aid
immediately.
WSM000001INI0008US0
PREPARE FOR EMERGENCIES
• Keep a first aid kit and fire extinguisher ready at all
times.
• Keep the emergency contact telephone numbers
near your telephone at all times.
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KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-4
2. SPECIFICATIONS
NOTE
• Specifications are subject to change without notice.
*: LPG regulator with vaporizer operates on a liquid withdrawal type system.
9Y1211108INI0001US0
Model WG972-GL-E4
Gasoline LPG
Number of Cylinder 3
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.)
SAE Net Continuous 17.6 kW / 3600 min-1 (rpm)
23.6 HP / 3600 min-1 (rpm)
16.3 kW / 3600 min-1 (rpm)
21.9 HP / 3600 min-1 (rpm)
SAE Net Intermittent 22.0 kW / 3600 min-1 (rpm)
29.5 HP / 3600 min-1 (rpm)
20.3 kW / 3600 min-1 (rpm)
27.2 HP / 3600 min-1 (rpm)
SAE Gross Intermittent 23.2 kW / 3600 min-1 (rpm)
31.1 HP / 3600 min-1 (rpm)
22.0 kW / 3600 min-1 (rpm)
29.5 HP / 3600 min-1 (rpm)
Maximum Bare Speed 3570 to 3630 min-1 (rpm)
Minimum Bare Idling Speed 970 to 1030 min-1 (rpm)
Cylinder Head Overhead-Valve
Ignition System Full Transistor Battery Ignition Type
Governor Electronic Governor
Direction of Rotation Counter-Clockwise (Viewed from flywheel side)
Spark Plug NGK BKR6E
Ignition Timing (no-load condition) 0.70 rad (40 °) before T.D.C. /
3600 min-1 (rpm)
0.37 rad (21 °) before T.D.C. /
3600 min-1 (rpm)
Firing Order 1-2-3
Compression Ratio 9.2 : 1
Lubricating System Forced Lubrication by Trochoid Pump
Oil Pressure Indication Electrical Type Switch
Lubricating Filter Full Flow Paper Filter (Cartridge Type)
Cooling System Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Starting System Electric Starting with Starter (12 V, 1.0 kW)
Starting Motor 12 V, 1.0 kW
Battery 12 V, 52 AH or equivalent
Charging Alternator 12 V, 480 W
Fuel Unleaded gasoline Commercial LPG*
Lubricating Oil Better than SL Class (API)
Lubricating Oil Capacity 3.4 L (0.90 U.S.gals)
Catalytic Muffler / Converter Three Way Catalyst
Weight (Dry) 74.0 kg (163 lbs) 77.7 kg (171 lbs)
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-5
9Y1211108INI0002US0
Model WG972-G-E4
Gasoline
Number of Cylinder 3
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.)
SAE Net Continuous 18.7 kW / 3600 min-1 (rpm)
25.1 HP / 3600 min-1 (rpm)
SAE Net Intermittent 23.1 kW / 3600 min-1 (rpm)
31.0 HP / 3600 min-1 (rpm)
SAE Gross Intermittent 24.2 kW / 3600 min-1 (rpm)
32.5 HP / 3600 min-1 (rpm)
Maximum Bare Speed 3570 to 3630 min-1 (rpm)
Minimum Bare Idling Speed 970 to 1030 min-1 (rpm)
Cylinder Head Overhead-Valve
Ignition System Full Transistor Battery Ignition Type
Governor Electronic Governor
Direction of Rotation Counter-Clockwise (Viewed from flywheel side)
Spark Plug NGK BKR6E
Ignition Timing (no-load condition) 0.70 rad (40 °) before T.D.C. /
3600 min-1 (rpm)
Firing Order 1-2-3
Compression Ratio 9.2 : 1
Lubricating System Forced Lubrication by Trochoid Pump
Oil Pressure Indication Electrical Type Switch
Lubricating Filter Full Flow Paper Filter (Cartridge Type)
Cooling System Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Starting System Electric Starting with Starter (12 V, 1.0 kW)
Starting Motor 12 V, 1.0 kW
Battery 12 V, 52 AH or equivalent
Charging Alternator 12 V, 480 W
Fuel Unleaded gasoline
Lubricating Oil Better than SL Class (API)
Lubricating Oil Capacity 3.4 L (0.90 U.S.gals)
Catalytic Muffler / Converter Three Way Catalyst
Weight (Dry) 74.0 kg (163 lbs)
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-6
NOTE
• Specifications are subject to change without notice.
*: LPG regulator with vaporizer operates on a liquid withdrawal type system.
9Y1211108INI0003US0
Model WG972-L-E4 WG972-N-E4
LPG CNG
Number of Cylinder 3
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.)
SAE Net Continuous 16.3 kW / 3600 min-1 (rpm)
21.9 HP / 3600 min-1 (rpm)
15.0 kW / 3600 min-1 (rpm)
20.1 HP / 3600 min-1 (rpm)
SAE Net Intermittent 20.3 kW / 3600 min-1 (rpm)
27.2 HP / 3600 min-1 (rpm)
18.8 kW / 3600 min-1 (rpm)
25.2 HP / 3600 min-1 (rpm)
SAE Gross Intermittent 22.0 kW / 3600 min-1 (rpm)
29.5 HP / 3600 min-1 (rpm)
20.4 kW / 3600 min-1 (rpm)
27.4 HP / 3600 min-1 (rpm)
Maximum Bare Speed 3570 to 3630 min-1 (rpm)
Minimum Bare Idling Speed 970 to 1030 min-1 (rpm)
Cylinder Head Overhead-Valve
Ignition System Full Transistor Battery Ignition Type
Governor Electronic Governor
Direction of Rotation Counter-Clockwise (Viewed from flywheel side)
Spark Plug NGK BKR6E
Ignition Timing (no-load condition) 0.37 rad (21 °) before T.D.C. /
3600 min-1 (rpm)
0.49 rad (28 °) before T.D.C. /
3600 min-1 (rpm)
Firing Order 1-2-3
Compression Ratio 9.2 : 1
Lubricating System Forced Lubrication by Trochoid Pump
Oil Pressure Indication Electrical Type Switch
Lubricating Filter Full Flow Paper Filter (Cartridge Type)
Cooling System Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Starting System Electric Starting with Starter (12 V, 1.0 kW)
Starting Motor 12 V, 1.0 kW
Battery 12 V, 52 AH or equivalent
Charging Alternator 12 V, 480 W
Fuel Commercial LPG* CNG
Lubricating Oil Better than SL Class (API)
Lubricating Oil Capacity 3.4 L (0.90 U.S.gals)
Catalytic Muffler / Converter Three Way Catalyst
Weight (Dry) 77.4 kg (171 lbs)
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-7
3. EMISSION REGULATION
[1] GENERAL
Along with E4 models, are yet available to be used in the following countries per output category.
Current and future emission regulations.
HC+NOx/CO (g/kW·h)
• *: with evaporative emission regulation
9Y1211108INI0004US0
[2] IMPORTANT ITEMS OF EXHAUST EMISSION REGULATION
(1) Important Notice
There are necessary emission-related items for compliance with emission regulations.
For mass-production Kubota prepares the installation instructions.
These instructions are provided for the final engine assemblers who must ensure the engine, exhaust system
(catalyst), intake system, gasoline fuel system and etc, are installed correctly in the engine's certified configuration.
(for EPA only)
Failing to these instructions when installing a certified engine in a piece of non-load equipment violates federal
law (40CFR 1068. 105(b)), subject to fines or other penalties as described in) the Clean Air Act.
9Y1211108INI0005US0
(2) Emission-Related Installation Instructions
1) Air Intake System
You must use the original air cleaner and inlet pipe to observe the applicable emissions laws.
2) Exhaust System
Kubota offers certified catalytic converter, catalytic muffler and O2sensor.
Catalyst parts and O2sensor other than Kubota must not be used because other catalyst and O2sensor are not
certified our engine.
3) Gasoline Fuel System
If your equipment uses a volatile liquid fuel (such as gasoline), it must use the original fuel system components
to observe the applicable emissions laws.
4) Gaseous Fuel System
You must use only the regulator with vaporizer Kubota offers and assemble the LPG fuel and CNG fuel system
parts according to the instructions.
5) Electrical System
You should wire correctly for securing the performance and safety.
6) Engine Labels
EPA/CARB label must be visible at any time. Be careful not to damage the label.
9Y1211108INI0006US0
kW, Disp. Model Type North
America Europe Japan
19 < P ≤30,
0.825 < L ≤1.0 WG972-E4 E4 Available Available None Available
Countries Power [kW], Disp. [L] 2014 2015 2016 2017 2018 2019 2020 2021
USA
CARB
P ≤19, 0.225 ≤L 8.0/549*
19 < P, L ≤0.825 8.0/549*
19 < P, 0.825 < L ≤1.0 6.5/375* 0.8/20.6*
EPA P ≤19, 0.225 ≤L 8.0/610*
19 < P ≤30, L ≤1.0 8.0/610*
Canada P ≤19, 0.225 ≤L 8.0/610
19 < P None
EU
P ≤19, 0.225 ≤L
Gas Engine is not
covered
12.1/610 8/610
19 < P < 56 None Σ2.7 to Σ0.8 / 4.4 to 20.6
Japan P < 19, 0.225 ≤L 12.1/610 8/610
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-8
4. PERFORMANCE CURVES
WG972-GL-E4
9Y1211108INI0007US0
(1) Torque
(2) B.S.F.C. (Brake Specific Fuel
Consumption)
(3) Engine Speed
(4) Brake Horsepower
a: Gasoline Use b: LPG Use
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-9
WG972-G-E4
9Y1211108INI0014US0
(1) Torque (2) B.S.F.C. (Brake Specific Fuel
Consumption)
(3) Engine Speed (4) Brake Horsepower
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-10
WG972-L-E4
9Y1211108INI0015US0
(1) Torque (2) B.S.F.C. (Brake Specific Fuel
Consumption)
(3) Engine Speed (4) Brake Horsepower
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-11
WG972-N-E4
9Y1211108INI0016US0
(1) Torque (2) B.S.F.C. (Brake Specific Fuel
Consumption)
(3) Engine Speed (4) Brake Horsepower
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-12
5. DIMENSIONS
WG972-GL-E4
9Y1211108INI0008US0
WG972-GL-E4
A516 mm (20.3 in.)
B393 mm (15.5 in.)
C503 mm (19.8 in.)
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-13
WG972-G-E4
9Y1211108INI0009US0
WG972-G-E4
A453 mm (17.8 in.)
B393 mm (15.5 in.)
C503 mm (19.8 in.)
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-14
WG972-L-E4, WG972-N-E4
9Y1211108INI0010US0
WG972-L-E4, WG972-N-E4
A516 mm (20.3 in.)
B393 mm (15.5 in.)
C503 mm (19.8 in.)
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-15
6. WIRING DIAGRAM
WG972-GL-E4
KiSC issued 07, 2015 A

INFORMATION
WG972-E4, WSM
I-16
KiSC issued 07, 2015 A