TROUBLESHOOTING 6 – 11
9. Oil Pressure Does Not Rise
Step Action Value(s) Yes No
1 Was the oil pressure warning lamp working OK? —
Go to Step 2 Replace the oil
pressure
warning lamp
2 Does the oil filter element clog? — Replace the oil
filter element Go to Step 3
3 Does the relief valve open? — Repair or
replace the
relief valve Go to Step 4
4 Does the oil strainer clog? — Clean or
replace the oil
strainer Go to Step 5
5 Was the oil pump working OK? (The pump related
parts worn etc.) —
Go to Step 6 Repair or
replace the oil
pump.
6 Was the rocker arm and/or relation parts worn? — Replace the
rocker arm
and/or relation
parts Go to Step 7
7 Was the camshaft and/or relation parts worn? — Replace the
camshaft
and/or relation
parts Go to Step 8
8 Was the crankshaft and/or relation parts worn? — Replace the
crankshaft
and/or relation
parts Go to Step 9
9 Are any DTC stored? — Go to indicated
DTC Solved
Table of pressure unit
Pressure kPa (kg/cm
2) 100
(1.0) 980
(10.0)
Resistance ohm 81 30
Electric current A 63.5 106.7
ENGINE MECHANICAL 6A – 3
Lubricating Flow ........................................................................................................ 6A- 126
Oil Pump and Oil Filter .............................................................................................. 6A- 127
Oil Pump ..................................................................................................................... 6A- 128
Disassembly............................................................................................................ 6A- 128
Inspection and Repair ............................................................................................ 6A- 129
Reassembly............................................................................................................. 6A- 130
Oil Filter and Oil Cooler ............................................................................................. 6A- 131
Disassembly............................................................................................................ 6A- 131
Inspection and Repair ............................................................................................ 6A- 132
Reassembly............................................................................................................. 6A- 133
Inter Cooler .................................................................................................................... 6A- 135
Removal .................................................................................................................. 6A- 136
Installation .............................................................................................................. 6A- 136
Special Tools.................................................................................................................. 6A- 137
6A – 4 ENGINE MECHANICAL
MAIN DATA AND SPECIFICATIONS
Engine model
Item 4JA1T (L) 4JA1TC
Engine type
Combustion chamber type
Cylinder liner type
Timing gear train system Four-cycle, overhead valve, water cooled
Direct injection
Dry type, chrome plated
Gear drive
No. of cylinders-bore stroke mm (in) 4 – 93 92 (3.66 3.62)
No. of piston rings Compression ring: 2 / Oil ring: 1
Total piston displacement cm3 (in3)
Compression ratio (to 1) 2,499(152.4)
18.5
Compression pressure Mpa(kg/cm2/psi) 3.0 (31.0/441) – 200 rpm
Engine weight (dry) kg (lb) Approximately 239 (527)
Fuel injection order 1 – 3 – 4 - 2
Fuel injection timing BTDC deg 8 -
Specified fuel type
Idling speed rpm
Valve clearances (At cold): Intake mm (in)
Exhaust mm (in)
Intake valves Open at (BTDC) deg
Close at (ABDC) deg
Exhaust valves Open at (BBDC) deg
Close at (ATDC) deg
Fuel system JIS No. 2, DIN/EN590, GB252-1944 Diesel fuel
730 25 (A/C Off)
850 25 (A/C ON)
0.4 (0.016)
0.4 (0.016)
24.5
55.5
54.0
26.0
Injection pump type BOSCH distributor VE type BOSCH distributor VP44 type
Governor type Mechanical (Half all speed
type) Electronically controled
Injection nozzle type
Injection nozzle opening pressure Hole with 5 orifices
Mpa(kg/cm2/psi) 1st 19.1 (195 / 2,773) 1st 19.0 (194 / 2,755)
2nd (Reference)
25.527.0
(260275 / 3,7023,920) 2nd (Reference)
34.035.5
(347362 / 4,9365,154)
Main fuel filter type
Lubricating system
Lubricating method Cartridge paper element and water separator
Pressure circulation
Specified engine oil (API grade) ISUZU genuine 10W – 30 (API CD of ACEA B2/B3)
ENGINE MECHANICAL 6A – 5
Engine model
Item 4JA1T (L) 4JA1TC
Oil pump type
Oil filter type
Oil capacity lit (US/UK gal)
Oil cooler type Gear
Cartridge paper element
6.2 (1.64/1.36)
Water cooled
Cooling system
Water pump type Centrifugal
Thermostat type Wax pellet with jiggle valve
Air cleaner type Dry paper element Viscous paper element
Battery type/voltage No. of units 80D26L 1
95D31L 1 (OPT)
Generator capacity V-A 12 – 60
12 – 80
Starter motor output V-Kw 12 – 2.3
Turbocharger model
Turbine type
Compressor type *IHI RHF 4H
Mixed flow type
Backward & rake
*IHI : Ishikawajima-Harima Heavy Industries., Ltd.
6A – 6 ENGINE MECHANICAL
MAIN DATA AND SPECIFICATIONS
Engine model
Item 4JH1TC
Engine type Four-cycle, overhead valve, water cooled
Combustion chamber type Direct injection
Cylinder liner type
Timing gear train system Dry type, chrome plated
Gear drive
No. of cylinders-bore stroke mm (in) 4 – 95.4 104.9 (3.76 4.13)
No. of piston rings Compression ring: 2 / Oil ring: 1
Total piston displacement liter
Compression ratio (to 1) 2,999
18.3
Compression pressure MPa(kg/cm2/psi) 3.0 (31.0/441) – 200 rpm
Engine weight (dry) kg (lb) MT : Approximately 249 (549)
AT : Approximately 236 (520)
Fuel injection order 1 – 3 – 4 - 2
Specified fuel type JIS No.2, DIN/EN590, GB252-1944 Diesel fuel
Idling speed rpm
700 25 (A/C OFF)
800 25 (A/C ON)
Valve clearances (At cold): Intake mm (in)
Exhaust mm (in)
Intake valves Open at (BTDC) deg
Close at (ABDC) deg
Exhaust valves Open at (BBDC) deg
Close at (ATDC) deg
Fuel system
Injection pump type 0.4 (0.016)
0.4 (0.016)
24.5
55.5
54.0
26.0
BOSCH distributor VP44 type
Injection nozzle type
Injection nozzle opening pressure
MPa(kg/cm
2/psi)Hole with 5 orifices
1st 19.5 (199/2,828)
2nd (Reference) 34.335.8 (350365/4,9805,197)
Main fuel filter type
Lubricating system
Lubricating method Cartridge paper element and water separator
Pressure circulation
Specified engine oil (API grade) ISUZU genuine 10W – 30 (API CD of ACEA B2/B3)
Oil pump type
Oil filter type Gear
Cartridge paper element
Oil capacity lit (US/UK gal)
6.2 (1.64/1.36) (For 4 2)
7.0 (1.85/1.54) (For 4 4)
Oil cooler type Water cooled
6A – 24 ENGINE MECHANICAL
SERVICING
Servicing refers to general maintenance procedures to be performed by qualified service personnel.
RTW36ASH000401
MODEL IDENTIFICATION
Engine Serial Number
The engine number is stamped on the rear left hand side
of the cylinder body.
The engine number is stamped in the plate in front of the
engine room as well.
AIR CLEANER
Element cleaning procedures will vary according to the
condition of the element.
Dust Fouled Element
Rotate the element with your hand while applying
compressed air to the inside of the element. This will blow
the dust free.
Compressed air pressure kPa (kg/cm
2 /psi)
392 – 490 (4 – 5/57 – 71)
LUBRICATING SYSTEM
Main Oil Filter (Cartridge Type Paper Element)
Replacement Procedure
1. Drain the engine oil.
2. Retighten the drain plug.
3. Loosen the used oil filter by turning it counterclockwise
with a filter wrench.
Filter Wrench: 5-8840-0200-0
RTW36ASH000101
4. Clean the oil cooler fitting face. This will allow the new
oil filter to seat properly.
5. Apply a light coat of engine oil to the filter O-ring.
6. Turn in the new oil filter until the filter O-ring is fitted
against the sealing face.
7. Use the filter wrench to turn in the filter an additional
2/3 turns.
8. Check the engine oil level and replenish to the
specified level if required.
130RY00003
6A-6
ENGINE MECHANICAL 6A – 25
Replenished Engine Oil MAX lit (US/UK gal)
Condition
Model Engine Dry
With oil filter
replacement Without oil
filter
replacement
4 2
4 4
(4JA1L/TC)6.2 (1.64/1.36) 5.2 4.2
(1.37 1.11
/ 1.14 0.92) 4.5 3.5
(1.19 0.93
/ 0.99 0.77)
4 2
(4JH1TC)
6.2 (1.64/1.36) 5.2 4.2
(1.37 1.11
/ 1.14 0.92) 4.5 3.5
(1.19 0.93
/ 0.99 0.77)
4 4
(4JH1TC) 7.0 (1.85/1.54) 6.2 5.2
(1.64 1.37
/ 1.36 1.14) 5.3 4.3
(1.72 1.14
/ 1.17 0.95)
9. Start the engine and check for oil leakage from the
main oil filter.
6A-7
FUEL SYSTEM
Fuel Filter Replacement Procedure
1. Remove the fuel filter by turning it counterclockwise
with a filter wrench.
Filter Wrench: 5-8840-0253-0 (J-22700)
Note:
Be careful not to spill the fuel in the filter cartridge.
RTW46ASH000501
2. Clean the fuel filter cartridge fitting faces.
This will allow the new fuel filter to seat properly
3. Apply a light coat of engine oil to the O-ring.
4. Turn in the fuel filter until the sealing face comes in
contact with the O-ring.
5. Turn in the fuel filter an additional 2/3 of a turn with a
filter wrench.
Filter Wrench : 5-8840-0253-0 (J-22700)
6. Operate the priming pump until the air discharged
completely from fuel system.
7. Start the engine and check for fuel leakage.
Note:
The use of an ISUZU genuine fuel filter is strongly
recommended.
041RY00009
6A – 42 ENGINE MECHANICAL
ENGINE REPAIR KIT
RTW36ALF000601
Removal Steps
1. Cylinder head gasket
2. Head cover gasket
3. Head cover cap nut gasket
4. Drain cock gasket
5. Crankshaft rear oil seal
6. Gear case gasket
7. Oil pan drain plug gasket
8. Oil pan gasket
9. Oil filter gasket
10. Joint bolt gasket 11. Vacuum pump gasket
12. Water pump O-ring
13. Water outlet pipe gasket
14. Intake pipe gasket
15. Thermostat housing gasket
16. Intake manifold gasket
17. Exhaust manifold gasket
18. Nozzle holder O-ring
19. Nozzle holder gasket
20. Crankshaft front oil seal
NOTE
Discard all O-rings, gaskets, and seals removed at disassembly and replace them with new ones. Reuse of
these parts will result in oil, water, and gas leakage.