Page 2825 of 6020

Engine Mechanical – V6 Page 6A1–48
Page 6A1–48
2.18 Engine Oil Leak Diagnosis
Introduction
It is important to correctly identify the source of an engine oil leak. For example, a power steering fluid leak or spillage
during servicing can travel across the va lley area of the engine and run-out the weep hole, which is located at the back of
the cylinder block. Failure to correctly identify the source of an engine oil leak can lead to unnecessary replacement of
engine components.
Most fluid leaks can be repaired by repairi ng or replacing the faulty component or resealing the gasket surface. However,
once a leak is identified it is im portant to determine and repair the c ause as well as the leak itself.
Locating and Identifying the Leak
Inspect the leaking fluid and determine whet her it is engine oil, transmission fluid, power steering fluid, brake fluid or
some other fluid. If unsure of the source of the leaking lubricant, a quick check of fluid levels should indicate where the
fluid is coming from, as one or more fluid level should be low.
Visual Inspection
Once the type of leaking fluid has been determined, a visual inspection of the affected system should be performed.
When performing the visual inspection:
1 Bring the vehicle to the normal operating temperature.
2 Park the vehicle over a large s heet of paper or other clean surface.
3 Leave the vehicle idling for 2-3 minut es, then check for dripping fluid.
4 If required, identify the type of fluid leak ing and the approximate location of the leak.
5 Visually inspect the suspected area. A small mirror may assist viewing areas that are difficult to see normally.
6 Check for leaks at all sealing surfaces and fittings.
7 Check for any cracked or damaged components.
8 If the leak cannot be located, completely clean the entire engine and surrounding components, drive the vehicle at
normal operating temperature for several k ilometres and then repeat Steps 3 to 8.
9 If the leak still cannot be located, proceed with either the Powder Method or Black Light and Dye Method as
outlined below.
Powder Method
1 Completely clean the entir e engine and surrounding components.
2 Apply an aerosol type powder (e.g. f oot powder) to the suspected area.
3 Operate the vehicle at normal operating temperature and at varying speeds for several kilometres.
4 Identify the source of the leak from the discoloration of the powder around the suspect components.
5 If required, use a small mirror to assist in vi ewing areas that are difficult to see normally.
6 Refer to Possible Causes for Engine Oil Leaks in this Section, and repair or replace components as required.
Black Light and Dye Method
A black light and die kit Tool No. J28428-E or a commercially av ailable equivalent is available to technicians to aid in
engine oil leak diagnosis. When using a black light and die kit fo r the first time, it is recommended the technician read the
manufacturers instructions prior to using the kit.
1 Add the specified amount of dye, as per manufacturers instructions, into the engine or suspected source of the oil
leak.
2 Operate the vehicle at normal operating temperature and at varying speeds for several kilometres.
3 With the vehicle parked on a flat leve l surface, aim the black light at the suspected component/s. The dyed fluid will
appear as a yellow path leading to the oil leak source
4 Refer to Possible Causes for Engine Oil Leaks in this Section, and repair or replace components as required.
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Page 2826 of 6020
Engine Mechanical – V6 Page 6A1–49
Page 6A1–49
Possible Causes for Engine Oil Leaks
Common possible causes for engine oil leaks are:
• higher than recommended fluid levels,
• higher than recommended fluid pressures,
• blocked or faulty fluid filters or pressure relief valve,
• blocked or faulty engine ventilation system,
• incorrectly tightened or damaged fasteners,
• cracked or porous components,
• incorrect gaskets or sealants used,
• incorrect gaskets or sealant installation,
• damaged or worn gaskets or seals, and
• damaged or worn sealing surfaces.
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Page 2827 of 6020
Engine Mechanical – V6 Page 6A1–50
Page 6A1–50
2.19 Engine Oil Pressure Diagnosis
If the engine oil pressure is below the specified value, inspect the engine and components for the following:
• loose oil filter adaptor bolts,
• faulty oil filter adaptor seals,
• worn or faulty oil pump,
• loose oil pump bolts,
• loose, blocked or damaged oil pump suction pipe,
• faulty oil pump suction pipe seal,
• faulty oil pump pressure relief valve,
• faulty or incorrectly installed oil gallery plugs,
• excessive bearing clearance in one of the following:
• connecting rods big end/s,
• crankshaft main journal/s,
• camshaft/s,
• camshaft sprocket/s, and
• cracked, porous or restricted oil galleries, or broken lash adjuster/s.
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Page 2828 of 6020
Engine Mechanical – V6 Page 6A1–51
Page 6A1–51
2.20 Accessory Drive Belt Diagnosis
Tension Check
NOTE
An accessory drive belt that squeaks when the
engine is started or st opped is considered normal
and has no effect on drive belt durability.
1 Start the engine and switch off the air-conditioning system . Allow engine to run until normal operating temperature
has been reached.
2 Turn the engine off and inspect the markings on the drive belt tensioner to confi rm the drive belt tension is
within the operating limits.
3 If the markings on the drive belt tensioner were outside the acceptable operat ing limits, replace the
accessory drive belt, refer to 3.5 Accessory Drive
Belt .
NOTE
The operating limits for acceptable drive belt
tension are when the driv e belt tensioner pointer
(1) is aligned between the outer edge of the
minimum and maximum tension marks (2).
Figure 6A1 – 21
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Page 2829 of 6020
Engine Mechanical – V6 Page 6A1–52
Page 6A1–52
Inspect
Figure 6A1 – 22 illustrates the various stages of belt wear to aid in belt replacement decisions. Condition of the belt ribs
is best judged where the belt is bent over one of the larger accessory drive system pulleys.
Figure 6A1 – 22
Legend
A New belt
B Moderately used belt – few cracks, some wear on ribs and in grooves. replacement is not required C Severely used belt – several cracks per 30 mm. Should be
replaced before chunking occurs.
D Failed belt – separation of ri b material from the backing
(chunking). Replace belt immediately.
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Page 2830 of 6020

Engine Mechanical – V6 Page 6A1–53
Page 6A1–53
Drive Belt Chirp
Definition
Accessory drive belt chirping can be defined as a high-pitched noise that is heard once per revolution of the drive belt or
a pulley.
NOTE
Chirping during start-up in cold damp conditions
that abates once the engine reaches operating
temperature is considered normal.
Diagnostic Aids
The symptom may be intermittent due to moisture on the driv e belts or pulleys. It may be necessary to spray a small
amount of water on the drive belt to dup licate and confirm a customers concern. If spraying water onto the drive belt
system duplicates the symptom, cleaning the belt pulleys may be the solution.
A loose or incorrectly installed body component, suspension component or other item may be the cause of the noise.
Test Description
The numbers below refer to steps in the diagnostic table.
2 The noise may not be engine related. This step is to confirm the engine is making t he noise. If the engine is not
making the noise, do not proceed further with this diagnostic procedure.
3 The noise may be an internal engine noise. Removing the drive belt and operating the engine briefly will confirm
whether or not the noise is related to the drive belt.
CAUTION
When running the engine with the accessory
drive belt removed, the coolant pump will not
be operating and the engine may overheat if
left unsupervised even for a short period.
NOTE
There may also be a number of DTCs set when
running the engine with the accessory drive belt
removed.
4 Inspect all drive pump pulleys for pilling. NOTE
Pilling is the small balls (p ills) or strings of rubber
in the belt grooves caused by the accumulation of
rubber dust.
6 Misalignment of the accessory drive system pulleys ma y be caused by incorrect mounting of an accessory drive
component (A/C compressor, generator etc.) or pulley. Misa lignment may also be caused by incorrect installation of
a pulley during a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across
two or three pulleys. If a misaligned pulley is found, refer to the relevant component service information for the
correct installation and removal procedures.
10 Inspecting the fasteners can elim inate the possibility that an incorrect fastener has been installed.
12 Inspecting the pulleys for being bent should include inspec ting for a dent or other damage that would prevent the
drive belt from not seating correctly in all of the pulley grooves or on the smooth surface when the back end of the
belt is used as the driving surface.
14 Replacing the drive belt when it is not damaged and there is no excessive p illing will only be a temporary repair.
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Page 2831 of 6020

Engine Mechanical – V6 Page 6A1–54
Page 6A1–54
Diagnostic Table
Step Action Yes No
1
Did you review the information provided in 2.2 Symptoms, and
perform the required inspections. Go to Step 2 Go to
2.2 Symptoms
2 Confirm the customer compla int. Is there a chirping noise?
Go to Step 3 Refer to Diagnostic
Aids in this Section
3 1 Remove the drive belt, refer to 3.5 Accessory Drive Belt.
2 Operate the engine for no more than 40 seconds.
Does the chirping noise still exist? Accessory drive
system OK.
Go to 2.2
Symptoms, and
restart the diagnosis
of the noise Go to Step 4
4
Inspect for severe pilling, i.e. in excess of 33% of the belt groove
depth.
Do the belt grooves have pilling? Go to Step 5 Go to Step 6
5 Clean the drive belt pulleys with a wire brush.
Are the belt pulleys clean? Go to Step 15 Go to Step 6
6 Inspect for misalignment of the pulleys.
Are the pulleys misaligned? Go to Step 7 Go to Step 8
7 Replace or repair misaligned pulleys.
Did you complete the repair? Go to Step 15 —
8
Inspect for any bent or damaged accessory drive component
mounting brackets.
Did you find any bent or damaged brackets? Go to Step 9 Go to Step 10
9 Replace or repair any bent or damaged Brackets. Did you complete the repairs? Go to Step 15 —
10 Inspect for missing, loose or incorrect fasteners.
Did you find any missing, loose or incorrect fasteners? Go to Step 11 Go to Step 12
11
Tighten any loose fasteners to the to rque specification as provided in
provided in 6. Torque Wrench Specifications.
Replace any incorrect or missing fasteners.
Did you complete the repairs? Go to Step 15 —
12 Inspect for a bent pulley.
Did you find any bent pulleys? Go to Step 13 Go to Step 14
13 Replace bent pulleys as required.
Did you complete the repair? Go to Step 15 —
14 Replace the accessory drive belt, re
fer to 3.5 Accessory Drive Belt.
Did you complete the repair? Go to Step 15 —
15
Reinstall the accessory drive belt and operate the system to confirm
the repair.
Did you correct the chirp noise? Accessory drive
system OK Go to 2.2
Symptoms, and
restart the diagnosis
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ISUZU KB P190 2007
Page 2832 of 6020

Engine Mechanical – V6 Page 6A1–55
Page 6A1–55
Drive Belt Squeal
Definition
Accessory drive belt squealing can be defined as a loud screeching noise caused by a slipping drive belt. Belt squeal is
unusual in multi-rib belts. Drive belt squeal generally occurs when a heavy load is applied to the drive belt, such as an
air-conditioning compressor engagement, snapping the throttle, se ized pulley or a faulty accessory drive component.
Diagnostic Aids
If the noise is intermittent, confirm the accessory drive components by varying t heir loads, making sure they are operated
to their maximum capacity. An overcharged A/C system, restrictions in the power steering pressure circuit or a faulty
generator or coolant pump are likely c auses of accessory drive belt squeal.
A loose or incorrectly installed body component, suspension component or other item may be the cause of the noise.
Test Description
The numbers below refer to steps in the diagnostic table.
2 The noise may not be engine related. This step is to confirm the engine is making t he noise. If the engine is not
making the noise, do not proceed further with this diagnostic procedure.
3 The noise may be an internal engine noise. Removing the drive belt and operating the engine briefly will confirm
whether or not the noise is related to the drive belt.
CAUTION
When running the engine with the accessory
drive belt removed, the coolant pump will not
be operating and the engine may overheat if
left unsupervised even for a short period.
NOTE
There may also be a number of DTCs set when
running the engine with the accessory drive belt
removed.
4 Confirms an accessory drive component does not have a se ized bearing. With the belt removed, test the bearings
in the accessory drive co mponents spin free and smooth.
5 Confirms the drive belt tensioner is operating correctly. If the drive belt tensioner is not operating correctly, drive
belt tension will not be maintained, resulting in a belt squealing noise
6 Confirms the belt is not too long, which would prevent the tensioner from working as intended. Also, if an
excessively long belt has been fitted, it may also be r outed incorrectly and may be turning an accessory drive
component in the wrong direction.
7 Misalignment of the pulleys may be caused by one of the following:
• Incorrect mounting of an accessory drive component,
• Incorrect installation of an accessory drive pulley or,
• Bent or damaged pulley.
Test for a misaligned pulley using a straight edge in the pulley grooves across 2 or 3 pulleys. If a misaligned pulley is found, refer to the relevant component service info rmation for the correct installation and removal procedures.
8 This test is to confirm the pulleys are the correct di ameter and/or width. Using a known good vehicle, compare the
pulley sizes.
Diagnostic Table
Step Action Yes No
1
Did you review the information provided in 2.2 Symptoms, and
perform the required inspections. Go to Step 2 Go to
2.2 Symptoms
2 Confirm the customer compla int. Is there a squealing noise?
Go to Step 3 Refer to Diagnostic
Aids in this Section
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ISUZU KB P190 2007