Doosan G424 Service Manual
Service Manual
G424 Gasoline/LP Engine
G424 LP Engine (Low Emission Version)
G20E-3, G25E-3, G30E-3
GC20E-3, GC25E-3, GC30E-3
SB2215E01
Oct.2001
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. Aperson 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.
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.
DAEWOO 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 DAEWOO 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. DAEWOO dealers have the most current information
available.
WARNING
1
G424 Service Manual Index
Index
GENERAL INFORMATION
.......................................
4
How to Read This Manual
....................................
4
Precaution Before Service
....................................
6
General
.................................................................
8
Tightening Torque
.................................................
9
Sealant
................................................................
12
SPECIFICATIONS
...................................................
13
General Specification
..........................................
13
Service Specification
..........................................
14
MAINTENANCE
......................................................
17
Test Fuel System for Leaks
................................
17
Check Engine Oil Level
......................................
17
Inspect Engine for Fluid Leaks
...........................
17
Change Engine Oil and Filter
.............................
17
Inspect Accessory Drive Belts............................
18
Inspect Electrical System
....................................
18
Inspect Vacuum lines and fitting
.........................
18
Check Coolant Level
...........................................
18
Inspect Coolant Hoses
........................................
18
Inspect Ignition System.......................................18
Replace Spark Plug
............................................
18
Replace LP fuel filter element
.............................
19
Test Fuelock (electric)
.........................................
19
Replace Gasoline Fuel filter
...............................
20
Inspect Gasoline Carburetor
...............................
20
Inspect Pressure Regulator/Vaporizer
................
20
Inspect LP Mixer (Standard LP Truck)
................
20
Inspect Variable Venturi Air/Fuel Mxer
(Low Emission LP Truck)....................................20
Inspect Complete Exhaust System for
Leaks,damage
....................................................
20
Engine Control Unit (ECU) and others
(Low Emission LP Truck)....................................
20
Maintenance Schedule.......................................
21
ENGINE SYSTEM
...................................................
22
Engine Overview
.................................................
22
Timing System
....................................................
25
Silent Shaft Mechanism
......................................
26
Auto Lash Adjuster
..............................................
27
Intake and Exhaust System
................................
28
Electrical System
................................................
30
STARTING SYSTEM
...............................................
32
General Description
............................................
32
Start Relay Test
..................................................
35
Start Motor
..........................................................
36
Operation
.......................................................
36
Removal and Installation
...............................
39
Disassembly and Reassembly
......................
42
CHARGING SYSTEM
..............................................
47
General Description
............................................
47
Alternator
............................................................
47
IGNITION SYSTEM.................................................
50
Breakerless Ignition System...............................
50
Distributor............................................................
51
Removal and Installation
....................................
54
Distributor, disassembly and reassembly...........
56
GASOLINE FUEL SYSTEM
....................................
58
General Description............................................
58
Geasoline Carburetor, Operation........................
59
Removal and Installation
....................................
64
Gasoline Carburetor
Disassembly and Reassembly............................
66
LPG FUEL SYSTEM ...............................................
73
General Description
............................................
73
Electric Fuelock Model
..................................
73
Converter
.......................................................
74
Fuel Tank
.......................................................
75
LP Relief Valve
..............................................
75
Carburetor
.....................................................
76
Tests or Adjustments
...........................................
77
Carburetor Adjustment
..................................
77
Fuel System Leak Check
..............................
79
Recommendation for LP Fuel System ..........
80
LP Converter - Check, Clean........................81
Disassembly and Assembly................................
82
LPG Carburetor.............................................
82
LP Gas Fuelock.............................................
84
LP Gas Converter..........................................85
LPG FUEL SYSTEM (LOW EMISSION VERSION)..
87
General Description
............................................
87
LP Carburetor
................................................
89
Vacuum switch (MAP)
...................................
90
Vacuum switch ..............................................
90
LP Converter.................................................
91
Fuel Control Valve.........................................
92
Fuelock Valve................................................
92
Engine Control Unit (ECU)............................
93
Oxygen Sensor..............................................
94
Catalytic Muffler.............................................
95
Tests or Adjustments...........................................
96
LP Carburetor - Check, Clean.......................97
LP Converter-Check,Clean ...........................
97
Inspection of Fuelock Valve ..........................
97
Inspection of Fuel Control Valve ...................
97
Inspection of Vacuum switch .........................
97
Inspection of Vacuum switch (MAP)..............
97
Inspection of Oxygen sensor.........................
98
Disassembly and Assembly................................
99
LPG Carburetor.............................................
99
LP Gas Converter........................................
101
2
G424 Service Manual Index3
DUAL FUEL SYSTEM
...........................................
102
GOVERNING SYSTEM
.........................................
103
General Description
..........................................
103
Governor,Disassembly and Reassembly
..........
104
LUBRICATION SYSTEM
.......................................
106
General Description
..........................................
106
Testing and Adjusting
........................................
107
Engine Oil
...............................................
107
Lubrication System Problem
..................
107
Oil Pressure Check
................................
109
COOLING SYSTEM
...............................................
110
General Description
..........................................
110
Testing and Adjusting
........................................
111
Cooling System Visual Inspection
...............
111
Cooling System Tests
..................................
111
Thermostat
...................................................
113
Cooling system Heat Problem
.....................
114
Cooling System Recommendation..............
114
Belt Adjustment............................................
116
V-belt Diagnosis
...........................................
116
Serivce Procedure
............................................
117
Draining and Filling Cooling System
...........
117
Flushing the Cooling System
.......................
118
Radiator Service..........................................
118
Removal & Install Water Temperature Sender..119
BASE ENGINE SERVICE PROCEDURE.............
120
Timing Belt
........................................................
120
Intake Manifold
.................................................
129
Exhaust Manifold and Water Pump
..................
130
Rocker Arms and Camshaft
..............................
133
Cylinder Head and Valves
................................
139
Front Case and Oil Pan
....................................
145
Piston and Connecting Rod
..............................
154
Crankshaft and Cylinder Block
.........................
162
ADJUSTMENT AND TROUBLESHOOTING
........
169
Adjustment
........................................................
169
Valve Clearnce Adjustment
.........................
169
Ignition Timing Adjustment
..........................
169
Idle Speed Adjustment
................................
171
Air Governor Adjustment .............................171
Anti-Hunting Adjustment
..............................
171
Troubleshooting
................................................
172
Engine Performance....................................
172
Engine Starting Problems ...........................
172
Charging System Problems
........................
173
Instrument Problems
...................................
173
Engine Noise
...............................................
174
Oil Pressure Diagnostics
.............................
176
Oil Pressure Problems
................................
177
Water in Engine
...........................................
178
Engine Overheting
.......................................
179
LP Fuel System
(Standard and/or Low Emission Version)....180
Troubleshooting Flow Chart
........................
187
General
..................................................
187
Engine
....................................................
189
Carburetor..............................................
190
Electrical Components
...........................
192
SPECIAL TOOLS
..................................................
195
Maintenance and Servicing Procedures
(1) Adiagram of the component parts is provided
near the front each section in order to give the
reader a better understanding of the installed
condition of component parts.
(2) The numbers provided within the diagram
indicate the sequence for maintenance and
servicing procedures; the symbol indicates a
non-reusable part; the tightening torque is
provided where applicable.
• Removal steps:
The part designation number corresponds to the
number in the illustration to indicate removal steps.
• Installation steps:
Specified in case installation impossible in reverse
order of removal steps. Omitted if installation is
possible in reverse order of removal steps.
• Disassembly steps:
The part designation number corresponds to the number
in the illustration to indicates disassembly steps.
• Reassembly steps.
Specified in case reassembly is impossible in
reverse order of disassembly steps. Omitted if
reassembly is possible in reverse order of
disassembly steps.
N
G424 Service Manual General Information
GENERAL INFORMATION
How To Read This Manual
Scope of Explanation
This book describes the service procedures for the engine removed from the vehicle.
For procedures concerning removal of the engine from the vehicle and on-vehicle inspection and servicing, refer
to the appropriate service manuals separately prepared for the individual models.
4
Classification of Major Maintenance/Service points
When there are major points relative to maintenance and servicing procedures (such as essential
maintenance and service points, maintenance and service standard values, information regarding the
use of special tools, etc.), these are arranged together as major maintenance and service points and
explained in detail.
A : Indicates that there are essential points for removal or disassembly.
B : Indicates that there are essential points for installation or reassembly.
Symbols for Lubrication, Sealants and
Adhesives
Information concerning the locations for
lubrication and for application of sealants and
adhesives if provided, by using symbols, in the
diagram of component parts, or on the page
following the component parts page, and
explained.
.... Sealant or adhesive
.... Engine oil or gear oil
Inspection
Only the inspections to be performed by using special tools or measuring instruments are covered. General
service procedures not covered in this manual, such as visual inspections and cleaning of parts, however, should
always be performed during actual service operations.
REMOVAL SERVICE POINTS
A Oil pan removal
(1) Remove the all oil pan bolts.
(2) Drive in the special tool between the cylinder block and oil pan.
(3) Side the tool by striking the edge of the special tool to separate the oil
pan from the cylinder block.
N
M
L
K
J
I
A
B
C
G424 Service Manual General Information5
1. Oil filter
2. Oil pressure switch
3. Drain plug
4. Drain plug gasket
5. Oil pan
6. Oil screen
7. Oil screen gasket
8. Plug
9. O-ring
10. Flang bolt
11. Relief plug
12. Gasket
13. Relief spring
14. Relief plunger
15. Oil filter bracket
16. Oil filter bracket gasket
This alphabetical letter corresponds to the one assigned
to a part in the removal, installation, disassembly or
reassembly steps that are indicated in the drawing on the
first page of each section.
Operating procedures, cautions, etc.
on removal, installation, disassembly
and reassembly are described
17. Oil pump case assembly
18. Front case gasket
19. Oil pump cover
20. Oil pump drive gear
21. Oil pump driven gear
22. Crankshaft front oil seal
23. Oil pump oil seal
24. Counterbalance shaft oil seal
25. Front case
26. Counterbalance shaft, left
27. Counterbalance shaft, right
28. Counterbalance shaft, front bearing
29. Counterbalance shaft, rear bearing, left
30. Counterbalance shaft, rear bearing, right
Removal steps
H
G
G
G
F
E
D
C
B
A
D
E
E
FRONT CASE AND OIL PAN
REMOVAL AND INSTALLATION
6EN1898
6EN0698
MD998727
G424 Service Manual General Information6
1EN0018
1EN0019
1EN0020
1EN0021
Precautions Before Servce
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.
SEALANT
G424 Service Manual General Information7
1EN0023
1EN0024
1EN0025
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.
1EN0022
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.
G424 Service Manual General Information8
6EN1916
General
Engine models and numbers
Indication of engine model and number
The engine model and serial number are stamped on the right side of cylinder block surface.
Engine model Fuel type
G424 Gasoline, LPG, LPG (Low Emission Version)
Engine model Engine number
4G64 AA0001 to YY9999
G424 Service Manual General Information9
Tightening Torque
Major Bolts and Nuts
Water pump pulley bolt
Crankshaft pulley bolt
Ignition system Spark plug
Distributor nut
Timing belt cover bolt
Tensioner spring spacer
Tensioner belt Tensioner bolt
Oil pump sprocket nut
Crankshaft bolt
Tensioner B bolt
Counterbalance shaft
Engine support bracket bolt
Camshaft sprocket bolt
Timing belt rear bolt
Fuel system Carburetor nut
carburetor Air horn nut
Stud
Fuel pump
Fuel system LPG carburetor nut
LPG carburetor Fuel pump cover
Intake manifold Water outlet bolt
Intake manifold bolt/nut
Exhaust Oil level gauge guide bolt
manifold Heat protector bolt
Exhaust manifold nut
Water inlet pipe bolt
Water pump bolt
Rocker arm
Rocker cover bolt
and camshaft Bearing cap bolt
M8
B 25
M6 B 65
Cylinder head,
valve Cylinder head bolt
Item Remarks
Torque
kg•m lb•ft N•m
0.9 6.5 9
2.5 18.1 25
2.5 18.1 25
1.2 8.7 12
1.1 8.0 11
0.9 6.5 9
4.9 35.4 48
4.9 35.4 48
5.5 39.8 54
12.0 86.8 118
1.9 13.7 19
4.6 33.3 45
3.6 26.0 35
9.0 65.1 88
1.4 10.1 14
1.2 8.7 12
1.2 8.7 12
1.2 8.7 12
1.1 8.0 11
1.2 8.7 12
1.1 8.0 11
1.4 10.1 14
1.8 13.0 18
1.4 10.1 14
0.9 6.5 9
3.5 25.3 34
1.4 10.1 14
1.4 10.1 14
0.6 4.3 6
2.4 17.4 24
2.0 14.5 20
8.0 kgf•m(57.9 lb•ft)[78 N•m]+ 0 +
2.0 kgf•m(14.5 lb•ft)[20 N•m]+
1/4 turn + 1/4 turn
G424 Service Manual General Information10
Drain plug
Oil pan bolt
Oil screen bolt/nut
Oil pressure switch
Front case, Plug
doil pan Flange bolt
Relief plug
Oil filter bracket
Oil pump cover bolt
Oil pump cover screw
Front case bolt
Piston, Connecting rod bearing nut
connecting rod.
Flywheel bolt
Rear plate bolt
Crankshaft,
cylinder block Rear plate cover
Oil seal case bolt
Bearing cap bolt
Starter motor Starter motor bolt
Item Remarks
Torque
kg•m lb•ft N•m
4.0 28.9 39
0.7 5.1 7
1.9 13.7 19
1.0 7.2 10
2.4 17.4 24
3.7 26.8 36
45 32.5 44
1.9 13.7 19
1.7 12.3 17
1.0 7.2 10
2.4 17.4 24
13.5 97.6 132
0.9 6.5 9
6.0 43.4 59
1.1 8.0 11
1.1 8.0 11
2.7 19.5 26
2.0 kg•m(14.5 lb•ft) [20 N•m]+ 1/4 turn
2.0 kg•m(14.5 lb•ft) [20 N•m]+ 1/4 turn
G424 Service Manual General Information11
General Bolts and Nuts Tightening Torque
Standard Bolts and Nuts
Nominal
Torque, kg•m (lb•ft) [N•m]
Pitch Bolt, stud, nut (with spring washer) Flange bolt, flange nut
diameter
M5 M5
M6 M6
M7 M7
M8 M8
M9 M9
M10 M10
Tapered Threads
Torque, kg•m (lb•ft) [N•m]
Size Material of internal threads: Material of internal threads:
Aluminum alloy Cast iron or steel
NPTF 1/16 0.5 to 0.8 (3.6 to 5.8) [5 to 8] 0.8 to 1.2 (5.8 to 8.7) [8 to 11]
PT 1/8 0.8 to 1.2 (5.8 to 8.7) [8 to 11] 1.5 to 2.2 (10.8 to 15.9) [15 to 21]
PT 1/4 2.0 to 3.0 (14.5 to 21.7) [20 to 29] 3.5 to 4.5 (25.3 to 32.5) [34 to 44]
NPTF 1/4 2.0 to 3.0 (14.5 to 21.7) [20 to 29] 3.5 to 4.5 (25.3 to 32.5) [34 to 44]
PT 3/8 4.0 to 5.5 (28.9 to 39.8) [39 to 59] 5.5 to 7.5 (39.8 to 54.2) [54 to 73]
PT 1/2 7.0 to 10.0 (50.6 to 72.3) [69 to 98] 12.0 to 16.0 (86.8 to 115.7) [118 to 156]
Head mark 4
-
-
1.2 (8.7) [12]
2.5 (18.1) [25]
4.2 (30.4) [41]
7.3 (52.8) [72]
Head mark 7
0.5 (0.5) [3.6]
0.9 (6.5) [8.8]
2.2 (15.9) [22]
4.5 (32.5) [44]
8.6 (60.0) [81]
14.0 (101.3) [137]
Head mark 10
-
1.2 (8.7) [12]
3.0 (21.7) [29]
6.0 (43.4) [59]
10.7 (77.4) [105]
14.5 (104.9) [142]
Head mark 4
-
-
1.3 (9.4) [13]
2.6 (18.8) [25]
4.7 (34.0) [46]
-
Head mark 7
0.6 (4.3) [5.9]
1.0 (7.2) [9.8]
2.4 (17.4) [24]
5.0 (36.2) [49]
9.5 (68.7) [93]
-
New Tightening Method-By Use of Bolts to be Tightened in Plastic Area
A new type of bolts, to be tightened in plastic area, is currently used in some parts of the engine. The tightening
method for the bolts is different from the conventional one. Be sure to observe the method described in the text
when tightening the bolts.
Service limits are provided for the bolts. Make sure that the service limits described in the text are strictly
observed.
•
Area where the bolts are in use:
(1) Cylinder head bolts
(2) Main bearing cap bolts
(3) Connecting rod cap bolts
•
Tightening method
After tightening the bolts to the specified torque, tighten them another 90° or 180° (twice 90°). The tightening
method varies on different areas. Observe the tightening method described in the text.
G424 Service Manual General Information12
Semi circular packing 3MTMAAD Part No.8672 or equivalent
Rocker cover 3MTMAAD Part No.8672 or equivalent
Oil pressure switch 3MTMAAD Part No.8672 or equivalent
Oil pan Silicone RTV sealant or eguivalent
Rear oil seal case Silicone RTV sealant or eguivalent
Rear plate bolt 3MTMAAD Part No.8672 or equivalent
Oil seal case bolt 3M
TM
AAD Part No.8672 or equivalent
Part to be Applied Brand
From in Place Gasket(FIPG)
The engine has several areas where the from-in-place gasket(FIPG) is in use. To ensure that gasket fully serves
its purpose, it is necessary to observe some precautions when applying the gasket. Bead size, continuity and
location are of paramount importance. Too thin a bead could cause leaks. Too thick a bead, on the other hand,
could be squeezed out of location, causing blocking or narrowing of the fluid feed line. To eliminate the possibility
of leaks from a joint, therefore, it is absolutely necessary to apply the gasket evenly without a break, while
observing the correct bead size.
Since the FIPG used in the engine hardens as it reacts with the moisture in the atmospheric air, it is normally
used in the metallic flange areas.
Disassembly
The parts assembled with the FIPG can be easily disassembled without use of a special method. In some cases,
however, the sealant between the joined surfaces may have broken by lightly striking with a mallet or similar tool.
A flat and thin gasket scraper may be lightly hammered in between the joined surfaces. In this case, however,
care must be taken to prevent damage to the joined surfaces. For removal of the oil pan, the special tool “Oil Pan
Remover” (MD998727) is available. Be sure to use the special tool to remove the oil pan.
Surface preparation
Thoroughly remove all substances deposited on the gasket application surfaces, using a gasket scraper or wire
brush.
Check to ensure that the surfaces to which the FIPG is to be applied is flat. Make sure that there are no oils,
greases and foreign substances deposited on the application surfaces. Do not forget to remove the old FIPG
remaining in the bolt holes.
From-in-place gasket Application
Applied FIPG bead should be of the specified size and without breaks. Also be sure to encircle the bolt hole
circumference with a completely continuous bead. The FIPG can be wiped away unless it is hardened. While the
FIPG is still moist (in less than 15 minutes), mount the parts in position. When the parts are mounted, make sure
that the gasket is applied to the required area only.
The FIPG application procedure may vary on different areas. Observe the procedure described in the text when
applying the FIPG.
Sealant
G424 Service Manual Specifications13
SPECIFICATIONS
General Specifications
Engine model
G424
Item
Type
No. of cylinders and arrangement
Combustion chamber type
Valve mechanism
Total displacement, cm3(cc) [cu in.]
Bore x stroke, mm (in.)
Dry weight, kg (lb)
Compression ratio
Compression pressure, kPa (kgf/cm2) [psi]
Intake Open
Valve timing
valve Close
Exhaust Open
valve Close
Firing order
Ignition timing, BTDC/rpm
Fuel pump Gasoline
Carburetor
Governor
Lubrication system
Oil pump
Oil filter
Cooling system
Water pump
Thermostat
Electrical system
Alternator, (12V-61A)
Starter motor, (12V-1.2kW)
Distributor
Spark plug (NGK) Gasoline
L. P. G.
Quantity of lubricating oil, cm3(liter) [U.S.gal]
Quantity of coolant, cm3(liter) [U.S.gal]
IDLE RPM LOW (RPM) 700 L 25
HIGH (RPM) 2700 L 50
Water-cooled, 4-cycle, gasoline-powered and L.P.G.-powered
4, in-line
Semi-spherical
OHC
2350 (2350) [143]
86.5
B 100 (3.41 B 3.94)
146 (322)
8.6
1128 (11.5) [163.5]
12° BTDC
40° ABDC
54° BBDC
6° ATDC
1 - 3 - 4 - 2
4°/740 (gasoline), 9°/740 (L.P.G.), 4˚/740(dual fuel)
Mechanical (diaphragm type)
Down-draft type
Air flow type
Pressure feed, full-flow filtration type
Gear, driven by timing belt
Filter paper, cartridge type
Water-cooled, forced circulation
Centrifugal, driven by V-belt
Wax type
12V DC, negative ground
Alternator current, built-in fan and regulator
Reduction drive
Equipped with automatic timing controller, breaker less type
BPR4ES
BPR5ES
4000(4.0) [1.06 ]( including 300 cm3(0.3 liter)[0.08 U.S.gal ]in oil filter
3100 (3.1) [0.82] (in engine proper)
G424 Service Manual Specifications14
Flatness of gasket surface
Grinding limit
Overall height
0.05 (0.0020)
0.25 (0.0098)
0.50 (0.0197)
Intake 0.30 (0.0118)
0.60 (0.0236)
Exhaust 0.30 (0.0118)
0.60 (0.0236)
Cam height
Intake
Exhaust
Journal diameter
Oil clearance
Overall length
Intake
Exhaust
Valve stem projection
Stem diameter Intake
Exhaust
Face angle
Thickness of valve Intake
head (margin) Exhaust
Stem-to-guide Intake
clearance Exhaust
Free height
Load/installed height
Out-of-squareness
Overall length
Intake
Exhaust
Inner diameter
Valve contact width
Sinkage
Outside diameter
Piston clearance
0.03 (0.0012)
89.9 to 90.1 (3.539 to 3.547)
13.05 to 13.07 (0.5138 to 0.5146)
13.25 to 13.27 (0.5217 to 0.5224)
13.50 to 13.57 (0.5315 to 0.5343)
47.30 to 47.33 (1.8622 to 1.8634)
47.60 to 47.63 (1.8740 to 1.8752)
40.30 to 40.33 (1.5866 to 1.5878)
40.60 to 40.63 (1.5984 to 1.5996)
41.62 (1.6386)
41.62 (1.6386)
33.935 to 33.950 (1.33602 to 1.33661)
0.05 to 0.09 (0.0020 to 0.0035)
106.6 (4.197)
105.2 (4.142)
42.05 (1.6555)
7.960 to 7.975 (0.31339 to 0.31398)
7.930 to 7.950 (0.31220 to 0.31299)
45° to 45.5°
1.2 (0.047)
2.0 (0.079)
0.025 to 0.058 (0.00098 to 0.00228)
0.050 to 0.088 (0.00197 to 0.00346)
48.0 (1.89)
176.5N (18kg) [39.7lbf]/40.4 (1.591)
2° or less
47 (1.85)
52 (2.05)
8.000 to 8.018 (0.31496 to 0.31567)
0.9 to 1.3 (0.035 to 0.051)
86.47 to 86.50 (3.4043 to 3.4055)
0.02 to 0.04 (0.0008 to 0.0016)
Service Specifications
Unit : mm(in.)
Cylinder headCamshaft
Valve
Valve spring
Valve guide
Valve seat
Piston
Oversize
rework
dimensions of
valve seat
ring hole
Standard value RemarksLimit
0.2 (0.008)
41.12 (1.6189)
41.12 (1.6189)
106.1 (4.126)
104.7 (4.122)
42.55 (1.6752)
47.0 (1.85)
4°
0.2 (0.008)
Total resurfacing
depth of both
cylinder head and
cylinder block
Item
Oversize rework
dimensions of valve
guide hole
G424 Service Manual Specifications15
End gap No. 1 ring
No. 2 ring
Oil ring
Ring-to-ring groove No. 1
clearance No. 2
Outside diameter
Press-in load
(at room temperature),
N (kg) [lbf]
Big end center-to small end center
length
Bend
Twist
Big end thrust clearance
End play
Journal outside diameter
Pin Outside diameter
Out-of-roundness and taper of
journal and pin
Concentricity journal and pin
Oil clearance of journal
Oil clearance of pin
Cylinder inner diameter
Flatness of gasket surface
Grinding limit
Overall height
Side clearance
Drive gear
Drive gear
Deflection
New belt
Used belt
Throttle bore diameter
Outer venturi diameter
Inner venturi diameter
Main jet (Symbol Size)
Main air jet diameter
Pilot jet diameter
Pilot air jet diameter
Primary throtle valve to throtle
bore clearance
0.25 to 0.40 (0.0098 to 0.0157)
0.45 to 0.60 (0.0177 to 0.0236)
0.20 to 0.60 (0.0079 to 0.0236)
0.03 to 0.07 (0.0012 to 0.0028)
0.03 to 0.07 (0.0012 to 0.0028)
22.002 to 22.005 (0.86622 to 0.86634)
7350 to 17160
(750 to 1750)
[1650 to 3860]
149.9 to 150.0 (5.902 to 5.906)
0.05 (0.0020)
0.10 (0.0039)
0.10 to 0.25 (0.0039 to 0.0098)
0.05 to 0.18 (0.0020 to 0.0071)
56.982 to 57.000 (2.24338 to 2.24409)
44.985 to 45.000 (1.77106 to 1.77165)
0.005 (0.00020)
0.03 (0.0012)
0.02 to 0.04 (0.0008 to 0.0016)
0.02 to 0.05 (0.0008 to 0.0020)
86.50 to 86.53 (3.4055 to 3.4067)
0.05 (0.0020)
289.9 to 290.1 (11.413 to 11.421)
0.08 to 0.14 (0.031 to 0.0055)
0.06 to 0.12 (0.0024 to 0.0047)
7.0 to 10.0 (0.28 to 0.39)
10 (0.39)
32 (1.26)
24 (0.94)
9 to 12 (0.35 to 0.47)
132.5
0.9 (0.035)
0.55 (0.0217)
1.6 (0.063)
1.1(0.043)
Piston ring
Piston pinConnecting rodCrankshaftCylinder block
Oil pump
Drive
belt
Carburetor
Standard value RemarksLimit
0.8 (0.031)
0.8 (0.031)
1.0 (0.039)
0.2 (0.008)
Total resurfacing
depth of both
cylinder head and
cylinder block
Item
Unit : mm(in.)
G424 Service Manual Specifications16
Nominal output, kW
Voltage, V
No-load characterstics Current, A
Speed, rpm
Outer diameter
Commutator Runout
Undercut
Pinion gap
Brush length
Start
End
End
Start
Primary coil resistance, Ω
Secondary coil resistance, Ω
Plug gap
Valve opening temperature, °C (˚F)
Fully opening temperature, ˚C (˚F)
Valve lift
Oil Pressure
Low Idle 50 kPa(7psi)
High Idle 450 kPa(65psi)
1.2
11.0
90 or less
3000
29.4 (1.16)
0.05 (0.0020)
0.5 (0.020)
0.5 to 2.0 (0.020 to 0.079)
0°/1000
20°/5000
0°/80
23°/280
1.08 to 1.32
22.1 to 29.9
0.7 to 0.8 (0.028 to 0.031)
82 (180)
95 (203)
8 (0.31) or more
Starter motorDistributor
Ignitio n coil
Spark plug
Tahermostat
Standard valueItem RemarksLimit
28.8 (1.13)
0.1 (0.0039)
0.2 (0.008)
Wear limit line
Centrifugal advance crank
angle/engine speed, °/rpm
Vacuum advance crank
angle/vacuum, °/mmHg
Unit : mm(in.)
G424 Service Manual Maintenance17
MAINTENANCE
G424 engine requires a certain amount of
maintenance. Suggested maintenance requirements
are contained in this section. The owner should,
however, develop his own maintenance schedule
using the requirements listed in this section and any
other necessary requirements resulting from optional
additions to the engine system.
Test Fuel System for Leaks
• Obtain a pump spray bottle.
• Fill with an approved leak test solution or a mixture
of water and dish soap.
• Spray a generous amount of the solution on the
entire fuel system including the fuel storage
container and fuel lines.
• Wait approximately 15-60 seconds then perform a
visual inspection of entire fuel system.
• Leaks will cause the soapy solution to bubble.
• Repair any leaks before continuing.
• Crank the engine through several revolutions. This
will energize the fuel lock and allow fuel to flow to the
pressure regulator/vaporizer. Apply additional leak
test solution to this portion of the fuel system and
inspect as above.
• Repair any fuel leaks before continuing.
Check Engine Oil Level
IMPORTANT : Care must be taken when checking
engine oil level. Oil level must be main-tained between
the "MIN" mark and the "MAX" mark on the dipstick. To
ensure that you are not getting a false reading, make
sure the following steps are taken before checking the
oil level.
1. Stop engine if in use.
2. Allow sufficient time (approximately 2 minutes) for
the oil to drain back into the oil pan.
3. Remove dipstick. Wipe clean and reinstall. Push
dipstick all the way into the dipstick tube.
4. Remove dipstick and note the oil level.
5. Oil level must be between the "MAX" and "MIN"
marks.
6. If the oil level is below the "MIN" mark, proceed to
Steps 7 and 8, and reinstall dipstick into the dipstick
tube.
7. Remove oil filler cap from the valve rocker arm
cover.
8. Add required amount of oil to bring level up to, but
not over, the "MAX" mark on dipstick.
NOTE: When refill engine oil, refill same oil as that
used before.
Inspect Engine for Fluid Leaks
• Start engine and bring up to operating temperature.
• Turn engine off.
• Inspect entire engine for oil and/or coolant leaks.
• Repair any/all leaks before continuing.
Change Engine Oil &Filter
• Start engine.
• Bring up to operating temperature.
• Shut down engine.
• Remove oil fill cap located in valve cover.
• Place drain pan under engine oil pan.
• Remove oil drain plug located at bottom of oil pan
and allow engine oil to drain.
CAUTION : OIL WILL BE HOT.
• Remove engine oil filter. Make sure the oil filter
gasket does not stick to engine.
CAUTION : OIL WILL BE HOT.
• Using a clean shop towel clean the engine oil filter
gasket mating surface.
• Fill oil filter with engine oil.
G424 Service Manual Maintenance18
• Lube oil filter gasket with engine oil.
• Install oil filter as per filter manufacturers
instructions. DO NOT OVER TIGHTEN
• Fill crankcase with engine oil.
• Start engine & run approximately 60 seconds.
• Shut down engine, wait approximately 2 - 5 minutes
and then check oil level.
• When oil level is satisfactory start engine and check
for any possible leaks.
• Repair any/all leaks before returning unit to service.
NOTE
Engine Oil Specification : See, Lubrication System
section
Inspect Accessory Drive Belts
See, "Testing & Adjusting" of Cooling System Section.
Inspect electrical system
• Clean battery outer surfaces with a mixture of baking
soda and water.
• Inspect battery outer surfaces for damage. Replace
as required.
• Remove battery cables and clean.
• Inspect battery cables for worn or missing insulation,
frayed wire and/or corrosion. Replace as required.
Inspect V acuum Lines and Fittings
• Visually inspect vacuum lines and fittings for physical
damage such as brittleness, cracks, kinks and
misrouting. Repair/replace as required.
• Solvent damage may cause vacuum lines to become
soft. Vacuum lines damaged by oil and/or other
solvents may collapse when the engine is running
effectively closing the passage inside the line.
Check Coolant Level
• Engine must be off and cold.
• NEVER REMOVE THE PRESSURE CAP ON AHOT
ENGINE.
• The coolant level should be equal to the "COLD"
mark on the coolant recovery tank. Periodically
remove the cooling system pressure cap and check
coolant level inside system. The coolant level should
be equal to the sealing surface of the pressure cap.
If level is low replace pressure cap and repair any/all
other leaks.
• On closed systems visually inspect the coolant
recovery tank and hoses for physical damage
• On open systems carefully remove cooling system
pressure cap. Coolant level will be approximately 3040 mm below pressure cap sealing surface. If level is
low replace pressure cap and repair any/all other
leaks.
Inspect Coolant Hoses
• Visually inspect coolant hoses and clamps.
• Replace any hose that shows signs of swelling,
cracking, abrasion hardening or any other
damage/deterioration.
• Top-up cooling system with approved coolant.
Inspect Ignition System
• Remove and inspect spark plugs. Replace as
required.
• Test secondary wires with an Ohmmeter. Maximum
resistance repair replace as required.
• Remove distributor cap and perform visual inspection
of distributor cap and rotor. Replace cap & rotor if
corrosion is found on contacts.
• Inspect distributor breaker unit and housing for signs
of corrosion. Repair replace as required.
Replace Spark Plugs
• Utilizing a gentle twisting motion remove the
secondary high voltage leads from the spark plugs.
Replace any damaged leads.
• Remove the spark plugs.
• Gap new spark plugs to proper specs.
• Apply anti-seize compound to spark plug threads.
• Install spark plugs.
• Do not over tighten.
• Install secondary high voltage leads.
G424 Service Manual Maintenance19
Replace LP Fuel Filter Element
Park the lift truck in an authorized refueling area with
the forks lowered, parking beake applled and the
transmission in NEUTRAL.
1. Close the fuel shutoff valve on the LP-Gas tank.
Run the engine until fuel in the line runs out and the
engine stops. Turn off the ignition switch and
disconnect switch (if equipped).
2. Scribe a line across the filter housing covers.
3.Remove the cover retaining screws.
4. Remove cover (5), magnet (4), spring (3) and
filter element (2) from bottom cover (1).
5. Replace the filter element (2).
6. Check bottom cover O-ring seal (6) for damage.
Replace it if necessary.
7. Install the filter element (2), spring (3), magnet
(4) and cover (5) on bottom cover (1). Align the
scribe line on the covers.
8. Install the cover retaining screws. Tighten the
screws in a sequence opposite each other.
9. Open the fuel valve by slowly turning the valve
counterclockwise.
10. Crank the engine only enough to produce a
vacuum at the fuelock. Turn the ignition key
switch off.
11. Check the fuel lines and fittings for leaks with a
soap solution. Make repairs if necessary.
Test Fuel Lock (Electric)
• Start engine.
• Locate electrical connector for fuel lock.
• Disconnect electrical connector.
• Engine will run out of fuel and stop in a short period
of time. (The length of time increases with any
increase in distance between the fuel lock and the
pressure regulator).
5
4
3
2
1
6
G424 Service Manual Maintenance20
Replace Gasoline Fuel Filter
(Gasoline Truck and Dual
Fuel Truck)
Fuel leaked or spilled onto hot surfaces or
electrical components can cause a fire.
Turn the disconnect switch OFF if fitted or
disconnect the battery when changing fuel
filters
1. Raise the hood and seat assembly.
2. Loosen Bolt(1) and clamps(2)(3).
3. Replace old fuel filter with new filter.
4. Fasten Bolt(1) and clamps(2)(3).
Inspect Gasoline Carburetor
See, gasoline carburetor in Gasoline fuel system
section.
Inspect Pressure
Regulator/Vaporizer
See, pressure regulator/vaporizer in LP fuel system
section.
Inspect LP Mixer
(Standard LP Truck)
See, LP mixer in LP fuel system section.
Inspect Variable Venturi
Air/Fuel Mixer
(Low Emission LP Truck)
See, Variable Venturi Air/Fuel Mixer in LP fuel
system(Low emission version) section.
Inspect Complete Exhaust
System for Leaks, Damage
• Perform visual inspection of exhaust system.
• Repair any/all leaks found.
Engine Control Unit(ECU)
and others
(Low Emission LP Truck)
The commander, oxygen sensor and vacuum control
solenoid are not serviceable. If faulty, they must be
replaced. See Trouble Shooting Section
1
2
3
WARNING
G424 Service Manual Maintenance21
Maintenance Schedule
CHECK POINT
General Maintenance Section
Test fuel system for leaks Prior to any service of maintenance activity
Inspect engine for fluid leaks O
Check engine oil and filter O
Change engine oil and filter O
Inspect accessory drive belts O
Inspect electrical system O
Inspect all vacuum lines and fittings O
Inspect all fuel fittings and hoses O
Replace timing belt and counter balance shaft belt. O
Check engine compression pressure O
Engine Coolant Section
Check coolant level O
Change coolant O
Inspect coolant hoses for leaks, cracks swelling, or deterioration O
Engine Ignition Section
Inspect battery for case damage and corroded Cables O
Inspect ignition system O
Check ignition timing-adjust as necessary O
Replace spark plugs O
Fuel Lock-Off/Filter Section
Replace LP fuel filter element O
Replce gasoline fuel filter O
Inspect lock-off and filter for fuel leaks O
Ensure lock-off stops fuel flow when engine is off O
Pressure Regulator Section
Test regulator pressures O
Inspect pressure regulator for oil build-up O
Inspect pressure regulator assembly for fuel/coolant leaks O
Carburetor Section
Check for air leaks in filter system O
Check for vacuum leaks on complete intake system
O
Inspect air/gas valve assembly O
Inspect air/fuel mixture throat O
Inspect gasoline carburetor
O
Check air cleaner indicator O
Inspect air cleaner O
Replace air filter element O
Engine Exhaust Section (Low Emission Version only)
Inspect exhaust manifold for leaks O
Inspect manifold-to-catalyst exhaust piping and Connections for leaks O
Inspect catalyst inlet and outlet and leaks O
Daily
Every
250hrs
or
a month
Every
500hrs
or
3 months
Every
1000hrs
or
6 months
Every
2000hrs
or
a year
Every
1000hrs
or
18 months
Interval Hours
G424 Service Manual Engine System22
ENGINE SYSTEM
Engine Overview
The cylinder blocks are made of the special cast iron
and employ 5-bearing, deep skirt system.
The cylinder heads have hemisphere combustion
chambers, are of cross flow type arranged with V-type
valves and high efficient combustion is intended.
The camshaft is located on the top of the cylinder
heads and driven by cog type timing belt.
Dual type exhaust manifold is employed in order to
reduce output loss by exhaust interference.
G424 Service Manual Engine System23
Gasoline Engine
G424 Service Manual Engine System24
LPG Engine ( Low Emission Version)
G424 Service Manual Engine System25
Timing System
The timing belt is meshed with the sprockets, the
crankshaft sprocket becomes the drive sprocket, and
thus functions to drive the camshaft and oil pump.
Timing belt
The timing belt is the cogged type, using rubber as its basic
material, and it employs a high-strength glass fiber core
which does not expand or contract.
The features of the cogged-type belt compared to a chin are
no expansion/contraction, low noise level, no necessity for
lubrication, light weight, etc.
G424 Service Manual Engine System26
Silent Shaft Mechanism
The silent shaft mechanism function mainly to
eliminate, by the action of the silent shafts
incorporated at both sides of the cylinder block, the
vertical vibromotive force of the engine as well as the
vibromotive moment in the rolling direction, thus
making possible quieter operation of the vehicle.
The two silent shafts are arranged as shown in the
figure below. The right silent shaft rotates in the same
direction as the crankshaft, and the left silent shaft
rotates in the opposites direction. Both of these silent
shafts rotate at speed twice that of the crankshaft.
Right silent shaft is driven by timing belt B, and the left
silent shaft is driven by drive gear.
G424 Service Manual Engine System27
Auto Lash Adjuster
These engines have auto lash adjusters that eliminate
the need for valve clearance adjustment and reduce
noises of the valve system. The auto lash adjuster
automatically absorbs change in the valve clearance
caused by engine temperature change or wear of
parts and adjusts the valve clearance always to zero.
(2) During Valve Lift
A small amount of oil leaks from the high pressure
chamber through a clearance between the body inside
and the plunger outside.
Operation of Auto Lash Adjuster
(1) At Start of Valve Lift
When the cam lifts up the rocker arm, the hydraulic
pressure immediately forces the ball in the high pressure
chamber against the seat, closing the high pressure
chamber.
(3) At end of Valve Lift
The plunger spring forces the body back to the initial
position and oil is supplied to the high pressure chamber
to make up for the leaked oil.
Construction
G424 Service Manual Engine System28
Intake and Exhaust System
The intake manifold employs the shape having good
intake performance.
The exhaust manifold employs a dual type and intend
the reduction of output loss due to exhaust
interference.
Gasoline Engine
G424 Service Manual Engine System29
LPG Engine (Low Emission Version)
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