engine ISUZU KB P190 2007 Workshop Repair Manual

Engine Cooling – V6 Engine Page 6B1–10

Fan Assembly connector

Figure 6B1 – 5

2.3 Coolant Pump
The coolant pump is a centrifugal vane impeller type pump. The pump consists of a housing and an impeller. The
impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades (vanes). W hen the impeller
rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by sealed
bearings. The sealed bearings do not need to be lubricated. Grease cannot leak out, dirt and water cannot get in as long
as the seal is not damaged or worn.
The coolant pump (1) is mounted to the engine front cover
and is driven by the crankshaft pulley (2) via a multi-ribbed
drive belt (3), turning the pump pulley (4), bolted to the
coolant pump flange (5). Coolant enters the engine
through the coolant inlet pipe and thermostat at the rear of
engine and passes through the engine to the coolant
pump on the front engine cover and exits via the coolant
outlet housing (6) located at the front of the intake
manifold.

Figure 6B1 – 6

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Engine Cooling – V6 Engine Page 6B1–11

2.4 Coolant Outlet Housing
The coolant outlet housing (1) is located at the front of the
intake manifold (2).


Figure 6B1 – 7
2.5 Thermostat
The thermostat housing (1) is located at the rear of the
engine between the coolant inlet pipe (2) and the rear of
the intake manifold, underneath the heater pipe assembly
(3).


Figure 6B1 – 8

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Engine Cooling – V6 Engine Page 6B1–12


Figure 6B1 – 9
Legend
1 Bypass Valve
2 Thermostat Retaining Bar
3 Thermostat Assembly Retaining Lugs
4 Wax Pellet 5 Air Bleed Valve
6 Piston Centre Support
7 Thermostat Housing
8 Piston 9 Rubber Diaphragm
10 Thermostat Spring
11 Bypass Spring

A wax pellet type thermostat is used in the coolant inlet passage to control the flow of coolant, providing fast engine
warm up and regulating coolant temperature. The wax pellet or power element in the thermostat expands when heated
and contracts when cooled. The wax pellet is connected through a piston to a valve and when the pellet is heated,
pressure is exerted against a metal valve, which is forced to open.
As the pellet is cooled, the contraction allows a spring to close the valve. Thus, the valve remains closed while the
coolant is cold, preventing circulation of coolant through the radiator, but allowing the coolant to circulate throughout the
engine to warm it quickly and evenly. As the engine becomes warm, the pellet expands and the thermostat opens,
permitting the coolant to flow through to the radiator where heat is transferred to the surrounding air, through the radiator
walls.
This opening and closing of the thermostat valve permits enough coolant to enter the radiator to keep the engine within
specified temperature limits.
The thermostat also provides a restriction in the cooling system, even after it has opened. This restriction creates a
pressure difference, which prevents cavitation at the coolant pump and forces coolant to circulate through the engine
block.

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Engine Cooling – V6 Engine Page 6B1–13

2.6 Coolant Filler Cap
Figure 6B1 – 10 Figure 6B1 – 11

The pressurised coolant filler cap (1), fitted to the filler neck (2) on the coolant outlet housing, causes the cooling system
to operate at higher than atmospheric pressure. The higher pressure raises the boiling point of the coolant, resulting in
increased engine cooling efficiency. The coolant filler cap contains a pressure valve (3) and a vacuum (atmospheric)
valve (4).
Referring to view ‘A’, the pressure valve is held against its seat by a spring (5), which determines the maximum operating
pressure of the cooling system (120 kPa ).
Referring to view ‘B’, the vacuum valve (4) is held against its seat by a light spring and opens during cool down because
of the drop in pressure with contraction of the coolant volume. This pressure drop over-comes the spring force and the
vacuum valve is opened, preventing the radiator hoses from collapsing. In addition, coolant can also flow back into the
cooling system from the coolant recovery reservoir while this valve is open maintaining a full volume of coolant within the
engine and radiator.

Should the radiator pressure cap require
replacement, only fit the correct cap (with the
correct pressure-rating) for this engine. Refer
to the current release of Partfinder™ for this
information.

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Engine Cooling – V6 Engine Page 6B1–14

2.7 Coolant Recovery Reservoir
The coolant is maintained at the ideal level in the radiator by the coolant filler cap and the coolant recovery reservoir,
resulting in increased cooling efficiency.
The coolant recovery reservoir is located on the left-hand side front of the engine compartment, between the radiator
support panel and air cleaner assembly. The coolant recovery reservoir is connected to the radiator overflow connection
by a small diameter hose.
As the engine temperature rises, the coolant is heated and expands. The fluid displaced by expansion flows from the
radiator into the recovery reservoir.
W hen the engine is turned OFF, the coolant contracts as it cools. Coolant is then drawn back into the radiator through
the coolant filler cap atmospheric valve.
Coolant level should be maintained between the MAX and
MIN indicator lines on the coolant recovery reservoir, as
shown in Figure 6B1 – 12, when the engine is cold.
The cooling system is designed to use a coolant, DEX-
COOL® long-life coolant or equivalent to GM specification
6277M (a mixture of ethylene glycol antifreeze and
corrosion inhibitors and water), rather than plain water to
maintain the integrity of the cooling system, and to prevent
oxidation occurring within the engine.
NOTE
Some HFV6 Series vehicle markets call for
DEX-COOL® long-life coolant and others for
its equivalent, known as Extended Life Anti-
freeze Coolant, conforming to GM specification
6277M. If in doubt regarding the correct
coolant to be used, refer to the Owner’s
Handbook.


Figure 6B1 – 12

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Engine Cooling – V6 Engine Page 6B1–15

2.8 Engine Coolant Temperature Sensor
An Engine Coolant Temperature (ECT) sensor (2) is
mounted in the left-hand side cylinder head, just above
the exhaust manifold. The ECT sensor is used in
conjunction with the instrument panel temperature gauge.
The ECT sensor generates a signal, which is used by the
engine management system for calculation of the various
engine management functions.
Figure 6B1 – 13 shows the wiring harness connector (1)
and the ECT sensor (2).
Refer to 6C1-1 Engine Management General Information
for further information on the ECT sensor.

Figure 6B1 – 13

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Engine Cooling – V6 Engine Page 6B1–16

3 Service Operations
3.1 Service Notes
Safety

• To avoid serious personal injury, never
remove the coolant filler pressure cap on
the coolant outlet housing when the
engine is hot, even if the cooling system
should require filling. Sudden release of
cooling system pressure is very
dangerous.
• The vehicle is fitted with an electric
radiator cooling fan. When working around
the engine compartment, keep clear of the
fan as it may start without warning.
Before removing the coolant filler cap, allow the engine to cool, then place a shop rag over the coolant filler cap and then
slowly turn the cap anticlockwise, approximately 1½ turns, until the pressure relief position is reached. The pressure
relief position will allow any remaining pressure within the system to escape into the coolant recovery reservoir. Continue
to rotate the cap anticlockwise until the cap can be safely removed.
Periodic Servicing
The cooling system requires little attention except for maintaining the coolant to the correct level in the recovery reservoir
and periodic servicing at the time or distance intervals as outlined in 0B Lubrication and Service.
Periodic servicing includes:
1 Checking coolant level. Refer to 3.3 Draining and Filling Cooling System in this Section.
2 Checking coolant concentration. Refer to 3.2 Coolant Maintenance – Testing Coolant Concentration in this Section.
3 Pressure test cooling system and coolant filler cap. Refer to 3.7 Pressure Testing in this Section.
4 Tighten hose clamps and inspect all hoses. Refer to 3.6 Coolant Hoses in this Section. Replace hoses if swollen or deteriorated.

Always wear protective safety glasses when
working with spring type hose clamps. Failure
to do so could result in eye injury.
5 Clean out cooling system, refer to 3.4 Cleaning Cooling System – Cooling System Flush, in this Section and refill. Refer to 3.3 Draining and Filling Cooling System in this Section.
Environmental Issues
To reduce environmental impact and maintenance cost, whenever the coolant is drained from any engine, the service
records are to be checked to determine when the coolant was last changed. If more than six months life is left before the
next coolant change, then the following procedure is to be followed:
1 W hen draining the coolant from the engine, use a clean container to hold at least 12 litres of coolant and ensure that the coolant is not contaminated in the draining process.
2 After repairs have been completed, refill the engine cooling system with the drained coolant.

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Engine Cooling – V6 Engine Page 6B1–17

3 Top up as required, using a 50 / 50 mix of clean water and the recommended coolant, which is either DEX-COOL®
long-life coolant or its equivalent, known as Extended Life Anti-freeze Coolant conforming to GM specification
6277M. Refer to 3.2 Coolant Maintenance and 3.3 Draining and Filling Cooling System in this Section, for the
necessary procedures and further information.
3.2 Coolant Maintenance

Do not mix different types of anti-freeze or
corrosion inhibitors, as they may be
incompatible. If a different type has been used
in the cooling system, flush the system with
clean water, refer to 3.4 Cleaning Cooling
System – Cooling System Flush in this
Section and refill cooling system with the
correct coolant. Refer to 3.3 Draining and
Filling Cooling System in this Section.
The cooling system is designed to use a coolant (a mixture of ethylene glycol antifreeze with added corrosion inhibitors,
and water), rather than plain water. The use of glycol also raises the boiling point and increases the cooling system
efficiency. For this reason, it is of the utmost importance that the correct concentration level of ethylene glycol in the
cooling system is maintained.
Addition of plain water into the cooling system when 'topping-up' may dilute the coolant mixture to a point where the
antifreeze / anti-boil and corrosion inhibitor properties of ethylene glycol become ineffective.
The coolant should comprise of a mixture 50% ethylene glycol antifreeze / inhibitor with 50% clear, clean water.
Ethylene glycol conforming to the correct specification is either named DEX-COOL® long-life coolant or its equivalent,
known as Extended Life Anti-freeze Coolant conforming to GM specification 6277M. Both are available in a number of
different quantities. Check the current release of Partfinder™ for specific details.

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Engine Cooling – V6 Engine Page 6B1–18

Topping Up the Cooling System
Under normal operating conditions, the cooling system
should not be topped up at the coolant filler cap. The level
can be checked at the coolant recovery reservoir, and
coolant (in the correct concentration with clear, clean
water) added as necessary to bring the level between the
MAX and MIN indicator lines on the coolant recovery
reservoir, as shown in Figure 6B1 – 14, when the engine is
cold.

Figure 6B1 – 14
Testing Coolant Concentration
To ensure the specified ethylene glycol concentration is maintained in the engine coolant, the coolant concentration must
be checked at the time or distance intervals outlined in the Owner’s Handbook or Service Booklet in the glove box.
NOTE
• While a number of coolant concentration
measuring devices are available, the two
preferred types are as described.
• The procedures detailed, apply to either
coolant type used.
Method 1 – Refractometer
NOTE
• Coolant tester, Tool No. J26568,
automatically compensates for temperature.
• Ensure that the eyepiece of the tester is free
of coolant before looking through it.
• Before each use, swing back the plastic cover
at the slanted end of the coolant tester,
exposing the measuring window and the
bottom of the plastic cover. Carefully wipe the
measuring window dry with a tissue or clean,
soft cloth. Close the plastic cover.
1 Check the calibration of the coolant tester as follows:

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Engine Cooling – V6 Engine Page 6B1–19

a Place a few drops of distilled water (between 21 and 29° C) onto the measuring window, then close the
plastic cover.
b Point the tester toward any light source, look into the eyepiece and check that the indicated reading is zero. If not, then re-calibrate the tester as detailed at the end of this Test Method, Calibrating the Tester.
2 Release the tip of the bulb pump from under the refractometer body. It is not necessary to remove the
complete pump from the tool.

Refer to 3.1 Service Notes in this
Section, for important safety items.
3 Carefully remove the coolant filler cap.
4 Insert the tube of the pump into the coolant, and then press the bulb to obtain a sample.
5 Bend the tube around and insert the end into the cover plate opening.
Figure 6B1 – 15
6 Press the pump bulb to deposit a few drops of coolant onto the measuring surface. Do not open the plastic cover when taking readings, as moisture evaporation will change the reading obtained.
7 Point the coolant tester toward any light source, looking into the eyepiece.
a The coolant protection reading is at the point where the dividing line between the light and
dark, crosses the scale.
b The scale for ethylene glycol (bold arrow) is the reference scale for either DEX-COOL®
long-life coolant or its equivalent, known as
Extended Life Anti-freeze Coolant conforming
to GM specification 6277M.
NOTE
The temperature scale is reversed from that of
a conventional thermometer. Below zero
readings are on the upper half of the scale.
8 A reading between – 30 and – 52 °C (corresponding
to a coolant concentration between 45 to 60%), is
satisfactory for the HFV6 engine cooling system.
Figure 6B1 – 16

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