Isuzu Diesel Engine 6HK1 Service manual

ENGINE MECHANICAL (4HK1, 6HK1) 1A-3

ISUZU DIESEL ENGINE (4HK1, 6HK1)

Precautions on Service Work

Matters that require attention in terms of
maintenance

To prevent damage to the engine and ensure reliability
of its performance, pay attention to the following in
maintaining the engine: When taking down the engine
on the ground, do not make the bearing surface of the
oil pan touch directly the ground. Use a wood frame, for
example, to support the engine with the engine foot and
the flywheel housing.

Because there is only a small clearance between the
oil pan and the oil pump strainer, it can damage the
oil pan and the oil strainer.

• When the air duct or air cleaner is removed, cover
the air intake opening to prevent foreign matter
from getting into the cylinder. If it gets into it, it can
considerably damage the cylinder and others while
the engine is operating.

• When maintaining the engine, never fail to remove
the battery ground cable. If not, it may damage the
wire harness or electrical parts. If you need
electricity on for the purpose of inspection, for
instance, watch out for short circuits and others.

• Apply engine oil to the sliding contact surfaces of
the engine before reassembling it. This ensures
adequate lubrication when the engine is first
started.

• When valve train parts, pistons, piston rings,
connecting rods, connecting rod bearings or
crankshaft journal bearings are removed, put them
in order and keep them.

• When installing them, put them back to the same
location as they were removed.

• Gaskets, oil seals, O-rings, etc. must be replaced
with new ones when the engine is reassembled.

• As for parts where a liquid gasket is used, remove
an old liquid gasket completely and clean it up
thoroughly so that no oil, water or dust may be
clung to them. Then, apply the designated liquid
gasket to each place anew before assembly.

• Surfaces covered with liquid gasket must be
assembled within 7 minutes of gasket application.
If more than 7 minutes have elapsed, remove the
existing liquid gasket and apply new liquid gasket.

• When assembling or installing parts, fasten them
with the specified tightening torque so that they
may be installed properly.

Matters that require attention in specifically dealing
with this engine.

Holes or clearances in the fuel system, which serve as
a passage of fuel, including the inside of the injector,
are made with extreme precision. For this reason, they
are highly sensitive to foreign matter and if it gets in, it
can lead to an accident on the road, for instance; thus,
make sure that foreign matter will be prevented from
getting in.
When servicing the fuel system, every precaution must
be taken to prevent the entry of foreign material into the
system.

• Before beginning the service procedure, wash the
fuel line and the surrounding area.

• Perform the service procedures with clean hands.
Do not wear work gloves.

• Immediately after removing the fuel hose and/or
fuel pipe, carefully tape vinyl bags over the
exposed ends of the hose or pipe.

• If parts are to be replaced (fuel hose, fuel pipe,
etc.) do not open the new part packaging until
installation.

Work procedure

• The fuel opening must be quickly sealed when
removing the fuel pipe, injection pipe, fuel injector,
fuel supply pump, and common rail.

• The eyebolts and gasket must be stored in a clean
parts box with a lid to prevent adhesion of foreign
matter.

• Fuel leakage could cause fires. Therefore, after
finishing the work, wipe off the fuel that has leaked
out and make sure there is no fuel leakage after
starting the engine.

1A-4 ENGINE MECHANICAL (4HK1, 6HK1)

How to read the model

4HK1

Name

1. Cast The Engine Model 2. Stamp An Engine Number

6HK1

ENGINE MECHANICAL (4HK1, 6HK1) 1A-5

1

Name

1. Stamp An Engine Number

Explanations on functions and operation

Electronic engine control

With the control unit, the range from injection to air
intake/exhaust, including fuel injection quantity,
injection timing, intake air restriction, EGR, and idling
rpm, is controlled.

Cylinder block

The cylinder block is cast-iron with the center distance
of each bore being equal and is of the highly rigid,
symmetrical structure with the crankshaft center being
the center. The bearing cap is of the ladder frame
structure and tightened up under the plastic range
rotation angle method.

WSHK0001

Cylinder liner

The cylinder liner is selected to match an internal
diameter of a bore of the cylinder block and built, which
is imprinted on the left side of the cylinder.

Piston

The piston is aluminum-alloy and an autothermatic
piston with a strut cast, while the combustion chamber
is a round reentrant type.

Cylinder head

The cylinder head is cast-iron and there are 4 valves
per cylinder. The angular tightening method of the
cylinder head bolt further increases reliability and
durability.

1A-6 ENGINE MECHANICAL (4HK1, 6HK1)

Crankshaft

Tuftriding is given, while on the No. 1 balance weight
imprinted is the grade of each journal diameter.

EGR system

Based upon data, including water temperature, engine
speeds or engine loads, it is controlled via Engine
Control Module (ECM) to purify exhaust by recycling
part of it.
Its main components include an EGR valve, an EGR
cooler and various sensors.

Connecting rod cap bolt

The angular tightening method of the connecting rod
cap bolt further increases reliability and durability.

Common rail-type electronic control injection
system

The common rail-type electronic control injection
system is composed of a fuel supply pump that sets the
target pressure of high-pressure fuel and supply it, a
common rail that measures such high-pressure fuel
and a fuel injector that turns it into a fine spray and
injects it. Each is controlled via ECM based upon
various signals, while injection timing or fuel injection
quantity is controlled under every possible driving
condition.

• Rotate the crankshaft to make the No.1 cylinder
meet the compression top dead center (TDC).

4HK1

6HK1

Fuel injector

The fuel injector is a 7-hole nozzle that adjusts fuel
injection quantity or injection timing by opening or
closing an electromagnetic valve on the head of the
fuel injector.
ECM corrects the dispersion of fuel injection quantity
between fuel injectors according to ID code data in
memory. At the replacement of fuel injectors, ID code
data should be stored in ECM.

Fuel filter with sedimenter

It is a fuel filter with sedimenter that gets rid of water by
making use of the difference in specific gravity between
light oil and water, which comes with an indicator that
notifies you that it is filled with water.

Preheating system

The preheating system consists the ECM, the glow
relay, glow plugs and the glow indicator lamp. The
preheating system is operated when the engine coolant
temperature is low, and make the engine easy to start.

Lubrication system

It is an oil filter with full-flow bypass, which uses a
water-cool oil cooler and oil jet to cool the piston.

WSHK0049

• Insert a 0.4 mm (0.016 in) thickness gauge into a
clearance between the rocker arm and the bridge
to check it and adjust it if needed.

Valve clearance mm (in)

Intake valve 0.4 (0.016)

Exhaust valve 0.4 (0.016)

Function check

Inspection/adjustment of valve clearance

1. Inspection of valve clearance

• Remove the cylinder head cover.

• Remove the fuel injector harness ASM.

• Loosen the terminal nuts alternately to remove.

• Remove the leak off pipe.

Caution:

Adjust while being cold.

2. Adjustment of valve clearance

Caution:

Adjust valve clearance carefully so that the bridge may
become level (hit the end of the 2 valve axes).

ENGINE MECHANICAL (4HK1, 6HK1) 1A-7

a. Completely loosen all of the bridge and rocker

arm adjusting nuts and adjusting screws
(4HK1: 8 nuts and 8 screws, 6HK1: 12 nuts and
12 screws).

b. Place a 0.4 mm (0.016 in) thickness gauge

between the No. 1 cylinder rocker arm end and
the bridge cap.

c. Tighten the rocker arm adjusting screw until the

thickness gauge is snug (not tight) between the
rocker arm end and the bridge cap.

d. Tighten the rocker arm lock nut.

e. Tighten the bridge adjusting screw until the

bridge contacts the valve head.

f. Tighten the bridge lock nut.

g. Check that the thickness gauge is still held

snugly between the rocker arm end and the
bridge cap. If it is too tight, slightly loosen the
bridge adjusting screw and lock nut to restore
snugness.

h. Remove the thickness gauge.

i. Repeat Steps 2 through 5 for the remaining

cylinders.

Tightening torque: 22 N⋅m (2.2 kg⋅m/16 lb ft)

• With a thickness gauge kept inserted, tighten
an adjusting screw of the bridge lightly and
make sure that the tip of the adjusting screw
touches the end of valve axis and the
movement of the thickness gauge has become
tight.

• Then, check if the end of the valve axis on the
opposite side is unstable or hits diagonally. If
so, loosen the bridge adjusting screw a little so
that the end of the valves on both sides may
touch properly.
Valve bridge clearance: ± 0.1 mm (0.0039 in) or
less

• After making an adjustment so that the end of
the valves on both sides may touch properly,
tighten up an adjusting screw nut of the bridge
with a flathead screwdriver so that the bridge
adjusting screw may not rotate.

Tightening torque: 22 N⋅m (2.2 kg⋅m/16 lb ft)

Caution:

If the adjusting screw of the bridge is poorly adjusted,
the bridge would tilt and be pushed down and seized,
which may damage the bridge guide, for example.
Thus, adjust it accurately.

Name

1. Rocker Arm

2. Bridge Cap

3. Bridge

Tightening torque:

Rocker arm adjustment
screw nut

Bridge adjustment screw
nut

22 N⋅m (2.2 kg⋅m/16 lb ft)

22 N⋅m (2.2 kg⋅m/16 lb ft)

1A-8 ENGINE MECHANICAL (4HK1, 6HK1)

Adjustment table (4HK1)

Cylinder No. 1234

Valve arrangement IN EX IN EX IN EX IN EX

No. 1 cylinder

Compression top dead center position

No. 4 cylinder

Compression top dead center position

{{{ {

×× ××

Adjustment table (6HK1)

Cylinder No. 123456

Valve arrangement IN EX IN EX IN EX IN EX IN EX IN EX

No. 1 cylinder

Compression top dead center position

No. 6 cylinder

Compression top dead center position

{{{{{{

×× ×× ××

• If the No. 1 cylinder is the compression TDC,
adjust a valve clearance with { mark given on
the table and if the No. 4 (4HK1) or No. 6
(6HK1) cylinder is the compression TDC, that
with × mark.

4HK1

6HK1

WSHK0002

• Attach the harness ASM to the fuel injector.
Tighten the harness bracket with the
designated torque.

Tightening torque: 48 N⋅m (4.9 kg⋅m/35 lb ft)

• Install the terminal nuts on the fuel injector.

ENGINE MECHANICAL (4HK1, 6HK1) 1A-9

4HK1

WSHK0003

Name

1. Fuel Injector Harness Connector

6HK1

Tightening torque: 2 N⋅m (0.2 kg⋅m/18 lb in)

Note:

• Tighten the terminal nuts alternately in order to
prevent imbalance in tightening because they are
unified.

• Do not tighten the nuts too tightly because it leads
to damage to the terminal stud.

• Install the cylinder head cover.
Refer to the “Cylinder Head Cover”.

Compression pressure inspection

• Warm-up the engine.

• Remove a negative terminal of the battery and
remove all the glow plugs.

• Remove the harness connector for the fuel injector
built on the lower head cover (no fuel will be
injected).

Caution:

When the harness connector is removed, ECM judges
that it broke down and DTC is recorded. Upon
completion of measurement, never fail to clear memory
of ECM.
(For how to clear memory of ECM, refer to the Engine
Control System Section)

1

WSHK0004

Name

1. Fuel Injection Harness Connector

• Install the negative terminal of the battery.

• Turn on the starter to emit foreign matter within the
cylinders.

• Install an adapter and a gauge of a compression
gauge of the special tool.

1A-10 ENGINE MECHANICAL (4HK1, 6HK1)

Compression gauge: 5-8840-2675-0 (J-26999-12)
Compression gauge adapter
4HK1: EN-46722
6HK1: 5-8840-2622-0

• Turn on the starter to inspect compression
pressure.

4HK1

Compression pressure MPa (psi) / 200 rpm

Standard 2.84 – 3.24 (412 – 469)

Limit 1.96 (284)

Differences among
the cylinders

6HK1

Compression pressure MPa (psi) / 200 rpm

Standard 3.24 (469)

Limit 2.26 (327)

Differences among
the cylinders

• Measure each cylinder one by one.

Caution:

To keep engine speed at 200 rpm or more, use fully
charged batteries.

• Remove a compression gauge of the special tool.

• Remove a negative terminal of the batteries.

• Install a harness connector for the fuel injector built
on the lower head cover.

• Install all the glow plugs.

Tightening torque: 20 N⋅m (2.0 kg⋅m/15 lb ft)

294 kPa (43)

294 kPa (43)

• Install the negative terminal of the battery.

ENGINE MECHANICAL (4HK1, 6HK1) 1A-11

Main Data and Specifications

Item Engine model 4HK1

Type Diesel/4-cycle/water cooled-type, inline four-cylinder

OHC

Combustion chamber form Direct injection type

Cylinder liner type Dry type

Number of cylinders - cylinder bore ×
strokes

Displacement cc (cu.in) 5193 (317)

Compression ratio 17.5

Compression pressure MPa (psi)/rpm 3.23 (468)/200

Idle speed rpm 800

Valve clearance Intake 0.4 (0.016) (cold)

mm (in) Exhaust 0.4 (0.016) (cold)

Ignition type Compressed ignition

Injection order 1 - 3 - 4 - 2

Lubricating system

Lubricating type Pressure type

Oil pump type Gear type

Volume of lubricating oil L (qts) 13.0 (13.7) — 20.5 (21.7)

Oil filter type Full flow filter (cartridge type)

Oil cooling type Built-in, water-cooling

Cooling system

mm (in) 4-115 (4.53) × 125 (4.92)

Cooling type Water cooling type

Radiator type Corrugated fin (pressure type)

Water pump type Centrifugal, belt type

Thermostat type 2 wax-type units

Thermostat valve-opening temperature °C (°F) 85 (185)

Volume of coolant L (qts) 14 (14.8) (incl. radiator)

Fuel system

Injection pump type Electronic control common rail type

Governor type Electronic type

Timer type Electronic type

Injection nozzle type Multi-hole type

7-hole and φ 0.16 mm (0.0063 in) inside diameter

Charging system

Generator type AC type

Power output V/A 24 - 50

Regulator type IC

1A-12 ENGINE MECHANICAL (4HK1, 6HK1)

Item Engine model 4HK1

Starting system

Starter type Reduction type

Power output V-kw 24 - 5.0

Preheat system type Glow plug

Glow plug standard voltage/electric current V/A 23 - 3.5

Item Engine model 6HK1

Type Diesel/4-cycle/water cooled-type, inline four-cylinder

OHC

Combustion chamber form Direct injection type

Cylinder liner type Dry type

Number of cylinders - cylinder bore ×
strokes

Displacement cc (cu.in) 7790 (475)

Compression ratio 17.5

Compression pressure MPa (psi)/rpm 3.04 (441)/200

Idle speed rpm For Hitachi products: 800, For JCB and Sumitomo

Valve clearance Intake 0.4 (0.016) (cold)

mm (in) Exhaust 0.4 (0.016) (cold)

Ignition type Compressed ignition

Injection order 1 - 5 - 3 - 6 - 2 - 4

Lubricating system

Lubricating type Pressure type

Oil pump type Gear type

Volume of lubricating oil L (qts) 28 (29.6) — 38 (40.2)

Oil filter type Full flow filter (cartridge type)

Oil cooling type Built-in, water-cooling

mm (in) 6-115 (4.53) × 125 (4.92)

products: 900

Cooling system

Cooling type Water cooling type

Radiator type Corrugated fin (pressure type)

Water pump type Centrifugal, belt type

Thermostat type 2 wax-type units

Thermostat valve-opening temperature °C (°F) 82 (180)

Volume of coolant L (qts) 14.5 (15.3)

Fuel system

Injection pump type Electronic control common rail type

Governor type Electronic type

Timer type Electronic type

ENGINE MECHANICAL (4HK1, 6HK1) 1A-13

Item Engine model 6HK1

Injection nozzle type Multi-hole type

7-hole and φ0.16 mm (0.0063 in) inside diameter

Charging system

Generator type AC type

Power output V/A 24 - 120

Regulator type IC

Starting system

Starter type Reduction type

Power output V-kw 24 - 5.0

Preheat system type Glow plug

Glow plug standard voltage/electric current V/A 23 - 3.5

Special tool

Illustration Tool Number/Description

5-8840-26750-0

J-26999-12

Compression gauge

EN-46722

Compression gauge

adapter

(4HK1)

5-8840-2622-0

Compression gauge

adapter

(6HK1)