Page 792 of 6020
TROUBLESHOOTING 6 – 7
4. Excessive Fuel Consumption
Step Action Value(s) Yes No
1 Was the air cleaner element clogged? — Clean or
replace the air cleaner
element. Go to Step 2
2 Was the air leakage found from the air intake side of
the turbocharger? —
Repair or
replace the air intake side of the
turbocharger. Go to Step 3
3 Was the turbocharger working completely? —
Go to Step 4 Replace the
turbocharger
4 Was there the fuel leakage? — Repair or
replace the fuel leakage part. Go to Step 5
5 Was the compression pressure OK? 3.0 MPa
(31.0 kg/cm2,
441 psi) at 200 rpm
Go to Step 6 Readjust the
valve clearance or replace the cylinder head gasket or
cylinder liner or
piston or piston ring or valve
and valve seat
6 Was the injection nozzle pressure or spray pattern normal? —
Go to Step 7 Replace the
injection nozzle
7 Are any DTC stored? — Go to indicated
DTC Solved
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Page 806 of 6020

SECTION 6A
ENGINE MECHANICAL
TABLE OF CONTENTS
PAGE
4 8
Standard Bolts ........................................................................................................... 6A - 8
Special Parts Fixing Nuts and Bolts ........................................................................ 6A - 9
Recommended Liquid Gasket ...................................................................................... 6A - 22
LOCTITE Application Procedure .................................................................................. 6A - 23
Servicing ...................................................................................................................... .. 6A - 24
Model Identification ................................................................................................... 6A - 24
Air Cleaner .................................................................................................................. 6 A - 24
Lubricating System.................................................................................................... 6A - 24
Fuel System ................................................................................................................ 6A - 25
Cooling System .......................................................................................................... 6A - 2 7
Valve Clearance Adjustment ..................................................................................... 6A - 31
Compression Pressure Measurement ..................................................................... 6A - 32
General Description ...................................................................................................... 6A- 3 6
Removal and Installation .............................................................................................. 6A- 37 Removal ...................................................................................................................... 6 A- 37
Installation .................................................................................................................. 6A- 40
Coolant Replenishment ......................................................................................... 6A- 41
Engine Warm-Up .................................................................................................... 6A- 41
Engine Repair Kit........................................................................................................... 6A - 42
Engine Overhaul ............................................................................................................ 6A- 43
Removal ...................................................................................................................... 6 A- 43
External Parts ......................................................................................................... 6A- 43
E N GINE MECHA NICA L 6A – 1
Main Dat a and Specif ications ....................................................................................... 6A -
Torque Specif ications ................................................................................................... 6A -
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Page 809 of 6020

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 deg8 -
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)
780 ± 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)
25.5 ∼27.0
(260 ∼275 / 3,702 ∼3,920) 2nd (Reference)
34.0 ∼35.5
(347 ∼362 / 4,936 ∼5,154)
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)
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Page 811 of 6020

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) 34.3 ∼35.8 (350 ∼365/4,980 ∼5,197)
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 W ater cooled
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6A – 18 ENGINE MECHANICAL
Fuel Injection System (4JA1L)
N·m (kg·m/lb·ft)
RTW 46AXF001101
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ENGINE MECHANICAL 6A – 19
Fuel Injection System (4JA1TC)
N·m (kg·m/lb·ft)
RTW 46AXF001201
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6A – 20 ENGINE MECHANICAL
Fuel Injection System (4JH1TC)
N·m (kg·m/lb·ft)
RTW 46AXF001301
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Page 830 of 6020

ENGINE MECHANICAL 6A – 25
Replenished Engine Oil MAX lit (US/UK gal)
Condition
Model Engine Dry
W ith oil filter
replacement W ithout 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.
RTW 66ASH003201
FUEL SYSTEM
Fuel Filter Replacement Procedure
1. Remove the fuel filter by turning it counterclockwise with a filter wrench.
Filter W rench: 5-8840-0253-0 (J-22700)
Note:
Be careful not to spill the fuel in the filter cartridge.
RTW 66ASH003301
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 W rench : 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
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