Doosan G643E User manual

Service Manual
G643E LP Engine
G643LP Engine
G35S-5, G40S-5, G45S-5, G50C-5, G55C-5
GC35S-5, GC40S-5, GC45S-5, GC50C-5, GC55C-5
G40SC-5, G45SC-5, G50SC-5, G55SC-5
G50S-5, G60S-5, G70S-5
SB4263E01
Dec. 2008

1
Important Safety Information
Most accidents involving product operation, maintenance and repair are caused by failure to observe basic
safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations
before an accident occurs. A person must be alert to potential hazards. This person should also have the
necessary training, skills and tools to perform these functions properly.
Read and understand all safety precautions and warnings before operating or performing lubrication,
maintenance and repair on this product.
Basic safety precautions are listed in the “Safety” section of the Service or Technical Manual. Additional safety
precautions are listed in the “Safety”section of the owner/operation/maintenance publication.
Specific safety warnings for all these publications are provided in the description of operations where hazards
exist. WARNING labels have also been put on the product to provide instructions and to identify specific
hazards. If these hazard warnings are not heeded, bodily injury or death could occur to you or other persons.
Warnings in this publication and on the product labels are identified by the following symbol.
WARNING
Improper operation, lubrication, maintenance or repair of this product can be dangerous and could
result in injury or death.
Do not operate or perform any lubrication, maintenance or repair on this product, until you have read
and understood the operation, lubrication, maintenance and repair information.
Operations that may cause product damage are identified by NOTICE labels on the product and in this
publication.
DOOSAN cannot anticipate every possible circumstance that might involve a potential hazard. The warnings
in this publication and on the product are therefore not all inclusive. If a tool, procedure, work method or
operating technique not specifically recommended by DOOSAN is used, you must satisfy yourself that it is
safe for you and others. You should also ensure that the product will not be damaged or made unsafe by the
operation, lubrication, maintenance or repair procedures you choose.
The information, specifications, and illustrations in this publication are on the basis of information available at the
time it was written. The specifications, torques, pressures, measurements, adjustments, illustrations, and other
items can change at any time. These changes can affect the service given to the product. Obtain the complete and
most current information before starting any job. DOOSAN dealers have the most current information available.

G643(E) Service Manual Index3
Index
Chapter 1. GENERAL INFORMATION
Precautions before Service ................................. 7
Tightening Torque ............................................. 10
Recommended Lubricants and Capacities....... 12
Engine Model and Engine Serial Number ......... 13
General Specification ........................................ 14
G643F/G643FE Engine Power and Torque........ 16
Chapter 2. RECOMMENDED
MAINTENANCE
General Maintenance......................................... 17
Test Fuel System for Leaks........................... 17
Inspect Engine for Fluid Leaks ...................... 17
Inspect Vacuum Lines and Fittings ................ 17
Inspect Electrical System .............................. 17
Inspect Foot Pedal Operation........................ 17
Engine Oil Classification................................ 18
Checking Engine Oil Level ............................ 19
Replacing Engine Oil and Filter ..................... 19
Checking Compressed Pressure................... 20
Cooling System Maintenance............................ 21
Coolant Recommendation............................. 21
Check Coolant Level..................................... 21
Inspect Coolant Hoses.................................. 21
Checking coolant leaks ................................. 22
Specific gravity test....................................... 22
Relation between Coolant concentration and
Specific Gravity............................................. 22
Checking and Adjusting Drive Belt ................ 23
Checking Belt for Damage ............................ 23
Ignition System Maintenance............................ 24
Inspect Battery System ................................. 24
Inspect Ignition System................................. 24
Inspection of Ignition Timing.......................... 24
Inspection of Spark Plug ............................... 25
Fuel System Maintenance ................................. 27
Replace LP Fuel Filter Element..................... 27
Testing Fuel Lock-off Operation .................... 27
Pressure Regulator/Converter Inspection ...... 28
Inspect Air/Fuel Valve Mixer Assembly.......... 28
Inspect for Intake Leaks................................ 28
Inspect Throttle Assembly............................. 28
Checking the TMAP Sensor(G643E only) ..... 28
Exhaust System Maintenance........................... 28
Inspect Engine for Exhaust Leaks ................. 28
Maintenance Schedule ...................................... 29
Chapter 3. ENGINE MECHANICAL
SYSTEM
General Information........................................... 31
Engine Outline.............................................. 31
Specification................................................. 32
Torque Specification..................................... 33
Engine Exploded View.................................. 41
Engine Construction ..................................... 45
Statement On Cleanliness And Care............. 45
Use Of Rtv Sealer And Anaerobic Gasket
Eliminator ..................................................... 46
Replacing Engine Gaskets............................ 47
Thread Repair .............................................. 47
Special Tools................................................ 48
Cooling System ................................................. 51
General Description ...................................... 51
Testing & Adjusting....................................... 52
Cooling System Recommendation ................ 55
Engine Lubrication ............................................ 57
General Description ...................................... 57
Testing and Adjusting ................................... 58
Disassembly of Engine...................................... 60
Tools And Shop Equipment .......................... 60
Accessory Removal...................................... 60
Cleaning ....................................................... 60
Draining The Engine ..................................... 60
Engine Flywheel Removal ............................ 61
Exhaust Manifold Removal ........................... 61
High Mounted Fan Bracket Removal............. 62
Coolant Pump Removal................................ 62
Valve Rocker Arm Cover Removal................ 63
Thermostat Removal .................................... 63
Intake Manifold Removal .............................. 64

G643(E) Service Manual Index4
Valve Train Component Removal.................. 64
Cylinder Head Removal ................................ 65
Torsional Damper Removal........................... 66
Oil Pan Removal........................................... 66
Oil Pump Removal........................................ 67
Engine Front Cover Removal ........................ 67
Timing Chain and Camshaft Sprocket Removal
..................................................................... 67
Camshaft Removal ....................................... 68
Balance Shaft Removal................................. 68
Piston and Connecting Rod Removal ............ 69
Crankshaft Rear Oil Seal Removal................ 70
Crankshaft Rear Oil Seal Housing Removal .. 70
Crankshaft Removal...................................... 71
Cleaning, Inspection, and Repair...................... 72
Cylinder Block............................................... 72
Cylinder Bore ................................................ 73
Measuring Cylinder Bore Taper and Out-Of-
Round........................................................... 73
Cylinder Bore Reconditioning ........................ 74
Boring.................................................... 75
Honing ................................................... 75
Piston Disassembly....................................... 76
Measuring Piston Pin-To-Piston Clearance ... 77
Piston Selection ............................................ 78
Piston Assembly ........................................... 78
Intake and Exhaust Manifolds ....................... 80
Camshaft ...................................................... 80
Camshaft Bearings ....................................... 81
Balance Shaft ............................................... 82
Timing Chain and Sprockets ......................... 82
Crankshaft Sprocket Replacement ................ 82
Coolant Pump............................................... 83
Oil Pan and Valve Rocker Covers ................. 83
Oil Pump....................................................... 83
Valve Train Components............................... 85
Valve Lifters.................................................. 86
Cylinder Head ............................................... 86
Disassembly .......................................... 86
Cleaning, Inspection, and Measurement .... 86
Repair.................................................... 88
Valve Rocker Arm Stud Replacement .... 89
Assembly............................................... 89
Thermostat and Coolant Outlet ..................... 90
Torsional Damper ......................................... 90
Crankshaft Bearings...................................... 91
Crankshaft Runout ........................................ 93
Crankshaft End Play ..................................... 93
Connecting Rod Bearings ............................. 93
Connecting Rod Side Clearance ................... 94
Assembly of Engine .......................................... 95
Prior to Assembly ......................................... 95
Crankshaft And Crankshaft Bearing Installation
..................................................................... 95
Crankshaft Rear Oil Seal Housing Installation ... 96
Crankshaft Rear Oil Seal Installation............. 96
Piston and Connecting Rod Installation......... 96
Balance Shaft Installation ............................. 98
Camshaft Installation .................................... 99
Timing Chain and Camshaft Sprocket
Installation ...................................................100
Engine Front Cover Installation....................100
Torsional Damper Installation ......................100
Torsional Damper Installation ......................101
Oil Pump Installation....................................101
Oil Pan Installation.......................................102
Cylinder Head Installation ............................104
Cylinder Head Installation ............................104
Valve Train Component Installation..............104
Valve Adjustment.........................................105
Intake Manifold Installation...........................105
Rocker Arm Cover Installation......................105
Exhaust Manifold Installation .......................107
Flywheel Housing Installation.......................107
Engine Flywheel Installation.........................108
Coolant Pump Installation ............................109
Engine Accessory Installation ......................109
Engine Setup and Testing............................109
Chapter 4. ENGINE ELECTRICAL
SYSTEM
Specifications...................................................110
Ignition Timing .............................................110
Ignition Sequence (Firing Order) ..................110
Ignition Coil .................................................110
Spark Plug...................................................110
Distributor....................................................111
Sensor Gap .................................................111
Ignition System.................................................112
General Description .....................................112
Ignition System Control.........................113
lgnition System Schematic for G643E ...114
lgnition System Schematic for G643 .....114
Ignition System Inspection ....................115

G643(E) Service Manual Index5
Ignition Component Checks ................. 115
Inspection of Spark Plug Wires ............ 116
Inspection of Spark Plug ...................... 117
Inspection of EST Distributor................ 118
Inspection of Ignition Coil ..................... 120
Disassembly and Assembly......................... 120
Ignition Coil.......................................... 120
EST Distributor .................................... 121
Ignition Timing Adjustment for G643 Engine 123
Final Timing Verification....................... 124
Ignition Timing Adjustment for G643E Engine
................................................................... 125
Charging System ............................................. 126
General Description .................................... 126
Troubleshooting Procedure ......................... 129
STARTING SYSTEM......................................... 134
General Description .................................... 134
Diagnosis Procedure................................... 135
Start Relay Tests ........................................ 137
Troubleshooting .......................................... 138
Starter Repair ............................................. 139
Chapter 5. ENGINE MANAGEMENT
SYSTEM (EMS)
General Information......................................... 140
Specifications.............................................. 140
Component Location ................................... 145
G643E EMS (Engine Management System)
Overview .......................................................... 148
General Description .................................... 148
LPG Fuel System Operation........................ 151
Electronic Throttle System .......................... 159
SECM......................................................... 163
SECM Wiring Diagrams for G643E.............. 166
G643 EMS (Engine Management System)
Overview .......................................................... 168
General Description .................................... 168
LPG Fuel System Operation........................ 171
Electronic Throttle System .......................... 174
Ignition System ........................................... 175
SECM......................................................... 176
SECM (Load/Speed Management).............. 176
EMS Inspection and Repair..............................181
Engine Control Module[G643E]....................181
Crank Shaft Position Sensor [G643E] ..........182
IAT (Intake Air Temperature) Sensor [G643E
and G643] ...................................................184
OxygenSensor (Pre-Catalyst) [G643E].........185
Oxygen Sensor (Post-Catalyst) [G643E] ......186
ECT (Engine Coolant Temperature) Sensor
[G643E and G643].......................................187
Angle Sensor-Accelerator [G643E and G643]
....................................................................190
Transmission Oil Temperature Switch [G643E]
....................................................................191
Electronic Throttle Body [G643E and G643].192
Chapter 6. LPG FUEL DELIVERY
SYSTEM
G643E LP System Inspection and Repair........193
Removal and Installation..............................193
Hose Connections ................................194
Removal and Installation of N-2007 LP
Regulator..............................................196
Removal and Installation of CA100 Mixer
for G643E.............................................197
Tests and Adjustments ................................199
N-2007 Regulator Service Testing ........199
AVV (Air Valve Vacuum) Testing ..........201
Idle Mixture Adjustment ........................201
Parts Description .........................................205
CA100 Mixer for G643E Engine ............205
N-2007 Regulator for G643E Engine.....207
G643 LPG System Inspection and Repair .......209
Removal and Installation..............................209
Hose Connections ................................210
Removal and Installation of N-2001 LP
Regulator/Converter .............................211
Removal and Installation of CA100 Mixer
for G643 ...............................................212
Tests and Adjustments ................................214
N-2001 Regulator Service Testing ........214
AVV (Air Valve Vacuum) Testing ..........216
Idle Mixture Adjustment ........................216
G643 LP Fuel Systems with O2 Sensor 216
Parts Description .........................................218
CA100 Mixer for G643 Engine ..............218
CA100 Disassembly and Service ..........220
CA100 Disassembled Service...............221
N-2001 Regulator for G643 Engine .......222

G643(E) Service Manual Index6
N2001 Regulator Disassembly Steps: .. 224
N2001 Disassembled Service .............. 226
Chapter 7. BASIC TROUBLESHOOTING
Preliminary Checks.......................................... 227
Before Starting............................................ 227
Visual/Physical check.................................. 227
Basic Troubleshooting Guide ......................... 228
Customer Problem Analysis Sheet .............. 228
Basic Inspection Procedure......................... 229
Connector Inspection Procedure ................. 230
Basic Troubleshooting .................................... 234
Intermittents................................................ 234
Corrective Action......................................... 234
Surges and/or Stumbles.............................. 235
Engine Cranking but Will Not Start / Difficult to
Start ........................................................ 236
Engine Cranking but Will Not Start / Difficult to
Start (cont’d.)........................................... 237
Lack of Power, Slow to Respond / Poor High
Speed Performance / Hesitation During
Acceleration ............................................ 238
Detonation / Spark Knock............................ 240
Backfire ...................................................... 241
Dieseling, Run-on ....................................... 241
Rough, Unstable, Incorrect Idle, or Stalling.. 242
Cuts Out, Misses......................................... 244
Poor Fuel Economy / Excessive Fuel
Consumption / LPG Exhaust Smell.......... 245
High Idle Speed .......................................... 246
Excessive Exhaust Emissions or Odors....... 247
Diagnostic Aids for Rich / Lean Operation ... 248
Chart T-1 Restricted Exhaust System Check ... 249
Chapter 8. ADVANCED DIAGNOSTICS
Reading Diagnostic Fault Codes .....................250
Displaying Fault Codes (DFC) from SECM
Memory .............................................................250
Clearing Fault (DFC) Codes .............................250
Fault Action Descriptions ................................251
Fault List Definitions ........................................251
Appendix
LPG And LPG Fuel Tanks ................................252
Regulatory Compliance....................................256
Special Conditions for Safe Use ......................256
Abbreviations ...................................................257

G643(E) Service Manual Chapter 1. General Information7
Chapter 1. GENERAL INFORMATION
Precautions before Service
Removal and Disassembly
For prevention of wrong installation or reassembly
and for ease of operation, put mating marks to the
parts where no function is adversely affected.
Special Tool
Be sure to use Special Tools when their use is
specified for the operation.
Use of substitute tools will result in malfunction of
the part or damage it.
Tightening Torque
Tighten the part properly to specified torque.
Sealant
Use specified brand of sealant.
Use of sealant other than specified sealant may
cause water or oil leaks.

G643(E) Service Manual Chapter 1. General Information8
Replacement Part
When oil seal, O-ring, packing and gasket have
been removed, be sure to replace them with new
parts.
However, rocker cover gasket may be reused if it is
not damaged.
Rubber Parts
Do not stain timing belt and V-belt with oil or water.
Therefore, do not clean the pulley and sprocket with
detergent.
Oil and Grease
Before reassembly, apply specified oil to the rotating
and sliding parts.
Genuine Part
When the part is to be replaced, be sure to use
genuine part.
For selection of appropriate parts, refer to the Parts
Catalog.
Electrical System
1. Be sure to disconnect the battery cable from the
negative (-) terminal of the battery.
2. Never pull on the wires when disconnecting
connectors.
3. Locking connectors will click when the connector
is secure.
4. Handle sensors and relays carefully. Be careful
not to drop them or hit them against other parts.

G643(E) Service Manual Chapter 1. General Information9
Precautions for catalytic Converter
CAUTION
If a large amount of unburned gasoline flows
into the converter, it may overheat and create a
fire hazard. To prevent this, observe the
following precautions and explain them to your
customer.
1. Use only unleaded gasoline.
2. Do net run the engine while the truck is at rest for
a long time. Avoid running the engine at fast idle
for more than 5 minutes and at idle speed for
more than 10 minutes.
3. Avoid spark-jump tests. Do spark-jumps only
when absolutely necessary. Perform this test as
rapidly as possible and, while testing, never race
the engine.
4. Do not measure engine compression for an
extended time. Engine compression tests must be
made as rapidly as possible
5. Do not run the engine when the fuel tank is nearly
empty. This may cause the engine to misfire and
create and extra load on the converter.
6. Avoid coasting with the ignition turned off and
during prolonged braking
7. Do not dispose of a used catalytic converter
together with parts contaminated with gasoline or
oil.

G643(E) Service Manual Chapter 1. General Information10
Tightening Torque
Tightening Torque Table of Standard Parts
Torque (kg·m)
Bolt nominal diameter
(mm) Pitch (mm)
Head mark 4 Head mark 7
M5 0.8 0.3 ~ 0.4 0.5 ~ 0.6
M6 1.0 0.5 ~ 0.6 0.9 ~ 1.1
M8 1.25 1.2 ~ 1.5 2.0 ~ 2.5
M10 1.25 2.5 ~ 3.0 4.0 ~ 5.0
M12 1.25 3.5 ~ 4.5 6 ~ 8
M14 1.2 7.5 ~ 8.5 12 ~ 14
M16 1.5 11 ~ 13 18 ~ 21
M18 1.5 16 ~ 18 26 ~ 30
M20 1.5 22 ~ 25 36 ~ 42
M22 1.5 29 ~ 33 48 ~ 55
M24 1.5 37 ~ 42 61 ~ 70
M5 0.8 0.3 ~ 0.4 0.5 ~ 0.6
M6 1.0 0.5 ~ 0.6 0.9 ~ 1.1
M8 1.25 1.2 ~ 1.5 2.0 ~ 2.5
M10 1.25 2.5 ~ 3.0 4.0 ~ 5.0
NOTE: The torques shown in the table are standard
vales under the following conditions.
1. Nuts and bolt are made of steel bar and
galvanized.
2. Galvanized plain steel washers are inserted.
3. All nuts, bolts, plain washers are dry.
NOTE: The torques shown in the table are not
applicable,
1. When spring washers, toothed washers and the
like are inserted.
2. If plastic parts are fastened.
3. If oil is applied to threads and surfaces.
NOTE: If you reduce the torques in the table to the
percentage indicated below under the following
conditions, it will be the standard value.
1. If spring washers are used : 85%
2. If threads and bearing surfaces are stained with
oil: 85%

G643(E) Service Manual Chapter 1. General Information11
General tightening torque
for bolts, nuts and taperlock studs
thread
size Standard torque
The following charts give the standard toque
values for bolts, nuts and taperlock studs of
SAE Grade 5 or better quality. Exceptions are
given in other sections of the Service Manual
where needed. inches Ib•ft. N•m*
Use these torques for
bolts and nuts with
standard threads (con-
versions are
approximate).
standaed thread
1/4
5/16
3/8
7/16
1/2
9/16
5/8
3/4
7/8
1
1-1/8
1-1/4
1-3/8
1-1/2
9 ± 3
18 ± 5
32 ± 5
50 ± 10
75 ± 20
110 ± 15
150 ± 20
265 ± 35
420 ± 60
640 ± 80
800 ± 100
1000 ± 120
1200 ± 150
1500 ± 200
12 ± 4
25 ± 7
45 ± 7
70 ± 15
100 ± 15
150 ± 20
200 ± 25
360 ± 50
570 ± 80
875 ± 100
1100 ± 150
1350 ± 175
1600 ± 200
2000 ± 275
Use these torques for
bolts and nuts on
hydraulic valve bodies.
5/16
3/8
7/16
1/2
5/8
13 ± 2
24 ± 2
39 ± 2
60 ± 3
118 ± 4
20 ± 3
35 ± 3
50 ± 3
80 ± 4
160 ± 6
Use these torques for
studs with taperlock
threads.
taperlock stud
1/4
5/16
3/8
7/16
1/2
9/16
5/8
3/4
7/8
1
1-1/8
1-1/4
1-3/8
1-1/2
5 ± 2
10 ± 3
20 ± 3
30 ± 5
40 ± 5
60 ± 10
75 ± 10
110 ± 15
170 ± 20
260 ± 30
320 ± 30
400 ± 40
480 ± 40
550 ± 50
7 ± 3
15 ± 5
30± 5
40 ± 10
55 ± 10
80 ± 15
100 ± 15
150 ± 20
230 ± 30
350 ± 40
400 ± 40
550 ± 50
650 ± 50
750 ± 70
B80625X1

G643(E) Service Manual Chapter 1. General Information12
Recommended Lubricants and Capacities
Recommended Lubricants
Lubricant Specification Remarks
Engine Oil API Classification SJ or above SAE 10W30 or SAE 5W30
Coolant (Antifreeze)
Automotive antifreeze
suitable for gasoline engines
having aluminum alloy parts
Concentration level 50%(normal)
Concentration level 40%(tropical)
Lubricant Capacities
Description G(C)35/40/45S-5,G50/60/70S-5
Oil Pan 4.3
Oil Filter 0.5
Engine Oil (liters)
Total 4.8
Engine 7.6
Radiator & Hoses 11.4
Coolant (liters)
Total 19

G643(E) Service Manual Chapter 1. General Information13
Engine Model and Engine Serial
Number
Engine
Model Fuel Type Emission
Regulation
G643E LP
EPA/CARB*
2007
Compliant
G643 LP
* EPA: Environmental Protection Agency
* CARB: California Air Resources Board
G643E Engine
•Comply with EPA 2007 Emission Regulation
•Electronic Control by ECM
•Certified LP System available
–Closed loop LP Carburetion system
•3-way Catalytic Muffler is standard
G643 Engine
•Not comply with EPA 2007 Emission Regulation
•Electronic Control by ECM
•Standard LP System available
–Open loop LP Carburetion system
•Muffler is standard
Indication of Engine Model and Serial
Number
Engine Model Engine Serial Number
G643E/G643 30700001 to 39999999
Features and Benefits of G643E/G643 Engine
•Valve seat inserts
–Valve seat system
•SOHC valve system
•Timing chain system
•Distributor Ignition system
•Electronic control system by ECM (Engine control
module)
–Drive-by-wire system
–Higher efficiency and lower fuel consumption
–Min./Max. governor control
–Automatic engine protection from overheating
and/or low engine oil pressure
–Automatic transmission protection from
overheating (G643E Engine only)
–Engine diagnostics by service-tool software
–Forklift ground speed limit (optional)

G643(E) Service Manual Chapter 1. General Information14
General Specification
G643E Engine G643 Engine
GENERAL DESCRIPTION
ENGINE TYPE: 90°4-Cycle V6, Water Cooled
COMBUSTION SYSTEM: Naturally Aspirated
INTAKE MANIFOLD Cast Iron, Dry
EXHAUST MANIFOLD Cast Iron, Dry
Pushrod Actuated Overhead Valves - 2 Per Cylinder
VALVE CONFIGURATION: Auto Lash adjustment by hydraulic valve lifter
CAMSHAFT DRIVING: Timing Chain System
BALANCE SHAFT: One Balance Shaft System
DISPLACEMENT: 4294 cc (262 CID)
BORE: 101.60 mm (4.00 in.)
STROKE: 88.39 mm (3.48 in.)
COMPRESSION RATIO: 9.4:1
COMPRESSIONPRESSURE: 690 kPa (100 psi) Minimum
FIRING ORDER: 1-6-5-4-3-2
WEIGHT: 296 Kg (653 lbs.), Wet
ENGINE ROTATION: Counter-Clockwise (CCW) when viewed from Flywheel End
FUEL TYPE: LPG
CRANK VENTILATION PCV System
IGNITION SYSTEM
IGNITION TYPE: Distributor System
IGNITIOIN TIMING: Electronic controlled by ECM
IGNITION COIL: 12 V operation volt
DISTRIBUTOR: Delco EST Distributor with ignition module
SPARK PLUGS: BOSCH 4205, 0.9mm (0.035in.) Air Gap
LUBRICATION SYSTEM
OIL PRESSURE (MIN. HOT): 28 kPa (4 psi) @ 700 RPM
124 kPa (18 psi) @ 2000 RPM
OIL TEMPERATURE:
Upper Limit: 130°C (266°F)
Recommended: 99 - 110°C (210 - 230°F)
Lower Limit: 80°C (176°F)
CRANKCASE CAPACITY: 4.3 L (4.5 qts.)
OIL FILTER: 0.47 L (0.5 qt.)
ENGINE OIL SPECIFICATION: API - SJ, SAE 10W30
COOLING SYSTEM
WATER PUMP ROTATION: Serpentine Belt Drive - Clockwise (CW) when viewed from engine front
THERMOSTAT: Opening Temperature: 82°C (180°F)
Fully Open Temperature: 96°C (205°F)
COOLING WATER CAPACITY 7.6 L (block only)

G643(E) Service Manual Chapter 1. General Information15
G643E Engine G643 Engine
LP FUEL SYSTEM
LP FUEL SYSTEM Closed loop LP Carburetion
System
Open loop LP Carburetion
System
MIXER:
Diaphragm Type Air Valve
Assembly inside, Downdraft
(Model: CA-100)
Diaphragm Type Air Valve
Assembly inside, Downdraft
(Model: CA-100)
REGULATOR: Two-Stage Negative Pressure
Regulator (Model: N-2007)
Two-Stage Negative Pressure
Regulator (Model: N-2001)
FUELTRIMVALVE (FTV): Dual Dither System None
FUEL FILTRATION: 40 Microns Maximum 40 Microns Maximum
ENGINE ELECTRICAL
ENGINECONTROLMODULE(ECM): 12 V operation volt, 48 pins of I/O 12 V operation volt, 24 pins of I/O
CRANK SENSOR Hall effect Sensor VR sensor built in Distributor
TMAP: Intake Air Temp. & Manifold
Absolute Press. Sensor
Intake Air Temp. & Manifold
Absolute Press. Sensor
PEDAL ANGLE SENSOR: Two-Output Signals (Installed on
Accelerator Pedal)
Two-Output Signals (Installed
on Accelerator Pedal)
OXYGEN SENSOR: Heated Exhaust Gas Oxygen
Sensor (HEGO)
12 V operation volt
None
ECT-ECM: Engine Coolant Temperature
Sensor for ECM
Engine Coolant Temperature
Sensor for ECM
ECT-GAUGE Engine Coolant Temp. Sensor for
GAUGE on Instrument Panel
Engine Coolant Temp. Sensor
for GAUGE on Instrument
Panel
TPS: Throttle Position Sensor (built in
Throttle Body)
Throttle Position Sensor (built
in Throttle Body)
THROTTLE BODY: Electronic Throttle Body Electronic Throttle Body
LP FUEL LOCK-OFF: 12 V operation volt 12 V operation volt
ENGINE OIL PR. S/W: 21.4 kPa (3.1 psi) 21.4 kPa (3.1 psi)
STARTER MOTOR: 12 Volt, 2.0 kW 12 Volt, 2.0 kW
ALTERNATOR: 12 Volt, 80 A 12 Volt, 80 A
EXHAUST SYSTEM
CATALYTIC MUFFLER: Three-way Catalyst with Metal
Substrate
Muffler without Catalyst

G643(E) Service Manual Chapter 1. General Information16
G643/G643E Engine Power and Torque
ENGINE MODEL unit G643E-LP G643-LP
kW 69.4 69.4
hp 93.0 93.0
PS 94.3 94.3
RATED POWER
rpm 2,450 2,450
N-m 284 294
lbf-ft 210 217
kgf-m 29.0 30.0
MAX TORQUE
rpm 1600 1600
GOVERNED SPEED rpm 2500 2500
LOW IDLE rpm 750 750

G643(E) Service Manual Chapter 2. Recommended Maintenance17
Chapter 2. RECOMMENDED MAINTENANCE
Suggested maintenance requirements for an engine equipped with an MI-07 fuel system are contained in this
section. The operator should, however, develop a customized maintenance schedule using the requirements
listed in this section and any other requirements listed by the engine manufacturer.
General Maintenance
Test Fuel System for Leaks
•Obtain a leak check squirt bottle or pump spray
bottle.
•Fill the bottle with an approved leak check solution.
•Spray a generous amount of the solution on the
fuel system fuel lines and connections, starting at
the storage container.
•Wait approximately 15-60 seconds, then perform a
visual inspection of the fuel system. Leaks will
cause the solution to bubble.
•Listen for leaks
•Smell for LPG odor which may indicate a leak
•Repair any leaks before continuing.
•Crank the engine through several revolutions. This
will energize the fuel lock-off and allow fuel to
flow to the pressure regulator/converter. Apply
additional leak check solution to the regulator/
converter fuel connections and housing. Repeat
leak inspection as listed above.
•Repair any fuel leaks before continuing.
Inspect Engine for Fluid Leaks
•Start the engine and allow it to reach operating
temperatures.
•Turn the engine off.
•Inspect the entire engine for oil and/or coolant
leaks.
•Repair as necessary before continuing.
Inspect Vacuum Lines and Fittings
•Visually inspect vacuum lines and fittings for
physical damage such as brittleness, cracks and
kinks. Repair/replace as required.
•Solvent or oil damage may cause vacuum lines to
become soft, resulting in a collapsed line while
the engine is running.
•If abnormally soft lines are detected, replace as
necessary.
Inspect Electrical System
•Check for loose, dirty or damaged connectors and
wires on the harness including: fuel lock-off,
TMAP sensor, O2 sensors, electronic throttle,
control relays, fuel trim valves, crank position
sensor, and cam position sensor.
•Repair and/or replace as necessary.
Inspect Foot Pedal Operation
•Verify foot pedal travel is smooth without sticking.

G643(E) Service Manual Chapter 2. Recommended Maintenance18
Engine Oil Classification
Recommended API classification: Above SJ
Recommended SAE viscosity classification
The following lubricants should be selected for all
engines to enhance excellent performance and
maximum effect.
1. Observe the API classification guide.
2. Proper SAE classification number should be
selected within ambient temperature ranges. Do
not use the lubricant with SAE classification
number and API grade not identified on the
container.
*1. 10W-30 engine oil is recommended
If 10W-30 is not applicable, proper engine oil will be possible according to temperature ranges.