2007 ISUZU KB P190 belt

Engine Mechanical – V6 Page 6A1–60
Page 6A1–60
Drive Belt Vibration
Definition
Accessory drive belt vibration can be defined as a drive belt that jumps, shakes or rattles. Accessory drive belt vibration
is usually indicated by one of the following:
• the vibration is engine speed related, or
• the vibration is sensitive to accessory drive system load.
Diagnostic Aids
The accessory drive components such as the A/C compre ssor or generator can have an affect on engine vibration.
To aid in locating which component is causing the vibration, vary the load to each accessory drive component in turn and
note the effect it has on the vibration if any.
Test Description
The numbers below refer to steps in the diagnostic table.
2 Confirms the symptom exists at the time of di agnosis. Other vehicle components may be causing the noise.
3 Confirms the accessory drive belt is the cause of the noise. Drive belt rumbling is often confused with an internal
engine noise due to the similarity in the description. 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 The drive belt may cause a vibration. Inspecting the drive belt is considerably easier while the drive belt is
removed.
6 Inspecting the fasteners can eliminate the possibility that an inco rrect fastener has been installed.
8 This step should only be performed if t he coolant pump is driven by the drive belt. Inspect the coolant pump for a
bent shaft. Also inspect the coolant pump bearings for smooth operation and excessive play. Compare the coolant
pump with a known good pump.
9 Accessory drive component brackets that are bent, cra cked or loose may put extra strain on the accessory
component causing it to vibrate.
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 rumbling 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 vibration noise still exist? Accessory drive
system OK.
Go to 4.2
Symptoms, and
restart the diagnosis Go to Step 4
4 Inspect the accessory drive belt for damage, wear, debris build-up or
sections of missing ribs.
Did you find any damage, wear, debris build-up or missing ribs? Go to Step 5 Go to Step 6
5 Install a new accessory drive belt, refer to 3.5 Accessory Drive Belt.
Did you replace the accessory drive belt? Go to Step 10 —

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–61
Page 6A1–61
Step Action Yes No
6 Inspect for incorrect, loose, missing or damaged fasteners.
Did you find any incorrect, loose, missing or damaged fasteners? Go to Step 7 Go to Step 8
7
Tighten any loose fasteners to the corre ct torque specification, refer to
6 Torque Wrench Specifications.
Replace any incorrect or missing fasteners.
Did you complete the repairs? Go to Step 10 —
8
Inspect the coolant pump for a bent shaft, refer to 6B1 Engine Cooling
– V6.
Did you find and repair a bent coolant pump shaft? Go to Step 10 Go to Step 9
9
Inspect for bent, cracked or damaged accessory drive component
mounting brackets.
Did you find and repair any bent brackets? Go to Step 10 Refer to Diagnostic
Aids in this Section
10 If required, reinstall the accessory drive belt and operate the system to
confirm the repair.
Did you correct the vibration? Accessory drive
system OK Refer to Diagnostic
Aids in this Section

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–62
Page 6A1–62
Drive Belt Falls Off
Definition
The drive belt falls off during normal operation or does not ride correctly on the accessory drive pulleys.
Diagnostic Aids
If the accessory drive belt repeatedly falls off the drive pulleys, this is most likely due to pulley misalignment.
An extra load that is quickly applied and released by an a ccessory drive component (e.g. A/C compressor) may cause
the accessory drive belt to fall off. In th is circumstance, confirm the fault by operating the accessory drive components in
turn, noting which one caused the belt to fall off.
Lack of drive belt tension may also cause the belt to fall o ff the pulleys. Low drive belt tension could be caused by one of
the following:
• an incorrect drive belt length,
• a faulty drive belt tensioner, or
• a stretched or faulty drive belt.
Test Description
The numbers below refer to steps in the diagnostic table.
2 Confirms the condition of t he drive belt. Damage may have occurred to the dr ive belt when it first fell off or it may
have been damaged which caused the belt to fall off.
4 Misalignment of the pulleys may be caused by:
• the incorrect installation or mount ing of an accessory drive component,
• the incorrect installation of an a ccessory drive component pulley, or
• a damaged or bent accessory drive pulley.
Test for a misaligned pulley using a suitable straight edge in the pulley grooves across two or more pulleys. If a
misaligned pulley is found, refer to the service informa tion for the particular component, for the correct pulley
replacement procedures.
5 Inspecting the pulleys should include an inspection for dents or other damage that would prevent the drive belt from
seating correctly in all of the pulley grooves or on the smooth surface of a pulley when the back side of the belt is
used.
6 Accessory drive component mounting brackets that are bent will cause the drive belt to fall off.
7 Inspection of the fasteners can eliminat e the possibility that an incorrect fastener was installed. Missing, loose or
incorrect fasteners may cause pulley misalignment from the fasteners moving under load. Over-tightening of the
fasteners may cause deflection of mounting brackets and result in misaligned accessory drive pulleys.
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 Inspect for a damaged accessory drive belt.
Did you find any damage on the drive belt? Go to Step 3 Go to Step 4
3 Install a new accessory drive belt, re
fer to 3.5 Accessory Drive Belt.
Does the drive belt continue to fall off? Go to Step 4 Go to Step 12
4 Inspect the accessory drive system pulleys for misalignment
Did you find and repair any misaligned drive system pulleys? Go to Step 12 Go to Step 5
5 Inspect for a dented or cracked accessory drive system pulley.
Did you find and repair any dented or cracked drive system? Go to Step 12 Go to Step 6
6 Inspect for bent accessory drive component mounting brackets.
Did you find and repair any bent mounting brackets? Go to Step 12 Go to Step 7
7 Inspect for incorrect, loose, missing or damaged fasteners.
Did you find any incorrect, loose, missing or damaged fasteners? Go to Step 8 Go to Step 9

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–63
Page 6A1–63
Step Action Yes No
8
Tighten any loose fasteners to the corre ct torque specification, refer to
6 Torque Wrench Specifications.
Replace any incorrect or missing fasteners.
Does the drive belt continue to fall off? Go to Step 9 Go to Step 12
9
Test the accessory drive belt tensi oner for correct operation, refer to
Accessory Drive Belt Tensioner Diagnosis in this Section.
Did you accessory drive belt tensioner operat e correctly? Go to Step 11 Go to Step 10
10 Replace the drive belt tensioner, refer to
3.7 Accessory Drive Belt Tensioner Assembly.
Does the drive belt continue to fall off? Go to Step 11 Go to Step 12
11 Inspect for a failed drive belt idler and drive belt tensioner bearings.
Did you find and repair any failed bearings? Go to Step 12 Refer to Diagnostic
Aids in this Section
12 If required, reinstall the accessory drive belt and operate the system to
confirm the repair.
Does the drive belt continue to fall off? Go to Step 2 Accessory drive
system OK

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–64
Page 6A1–64
Drive Belt Excessive Wear
Definition
Excessive wear can be defined as wear at the outside ribs of the drive belt (frayed edges), usually caused by an
incorrectly installed drive belt
Diagnostic Aids
Excessive wear of a drive belt is usually caused by an incorre ct installation or an incorrect drive belt fitted. Minor pulley
misalignment will not cause excessive wear, but will cause the drive belt to fall off. Major pulley misalignment may cause
excessive wear, but would also re sult in the drive belt falling off.
Test Description
The numbers below refer to steps in the diagnostic table.
2 Confirms the drive belt is correctly installed onto all of the accessory drive system pulleys. Wear on the drive belt
may be caused by incorrectly positioning the drive belt by one or more grooves to a particular pulley.
3 The installation of the drive belt that is the incorrect width will cause wear on the drive belt. The drive belt ribs
should match all the grooves on all the pu lleys in the accessory drive system.
4 Confirms the drive belt is not cont acting any parts of the engine or body wh ile the engine is running. There should
be sufficient clearance when the accessory drive component loads varies. The drive belt should not come into
contact with any engine or body parts.
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 Inspect the accessory drive belt for correct installation.
Is the drive belt installed correctly? Go to Step 5 Go to Step 3
3 Ensure that the drive belt is
the correct one for the application.
Is the correct drive belt installed? Go to Step 5 Go to Step 4
4 Is the drive belt contacting any engine or body components with the
engine running? Go to Step 6 Refer to Diagnostic
Aids in this Section
5 Install a new accessory drive belt, re fer to 3.5 Accessory Drive Belt.
Did you replace the accessory drive belt? Go to Step 6 —
6 If required, reinstall the accessory drive belt and operate the system to
confirm the repair.
Did you correct the excessive wear? Accessory drive
system OK Go to Step 2

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–65
Page 6A1–65
Accessory Drive Belt Tensioner Diagnosis
Diagnostic Table
Step Action Yes No
1 1 Remove the accessory drive belt.
2 Inspect the drive belt tensioner pulley.
Is the drive belt tensioner pulley loose or misaligned? Go to Step 4 Go to Step 2
2 Rotate the drive belt tensioner.
Does the drive belt tensioner ro tate freely, without any unusual
resistance or binding? Go to Step 3 Go to Step 4
3 1 Using a suitable torque wrench, measure the torque required to
lift the drive belt tensioner off the stop.
2 Using a known good tensioner, m easure the torque required to
lift the drive belt tensioner off the stop.
Is the first torque reading within 10% of the second reading? Accessory drive belt
tensioner OK Go to Step 4
4 Replace the drive belt tensioner, refer to
3.7 Accessory Drive Belt Tensioner Assembly.
Is the repair complete? Accessory drive belt
tensioner OK —

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–72
Page 6A1–72
3.5 Accessory Drive Belt
RWD Vehicle
Remove
1 Remove the air intake duct from between the air flow meter and the throttle body, refer to
Section 6C1-3 Engine Management – V6 – Service Operations.
2 Note the accessory drive belt (1) routing.
Figure 6A1 – 29
3 Using a suitable ½” drive socket bar (1), rotate the drive belt tensioner (2) clockwise, to reduce belt
tension.
4 While holding the tensioner in the reduced tension
position, remove the accessory drive belt (3).

NOTE
If required use an assistant to maintain the tensioner in the required position.
CAUTION
If 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.
Figure 6A1 – 30

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–73
Page 6A1–73
Reinstall
1 Install the drive belt over the A/C compressor, idler pulley, power steering pump, coolant pump, generator and
tensioner pulleys.
2 Using a suitable ½” drive socket bar (1), rotate the driv e belt tensioner (2) clockwise, refer to Figure 6A1 – 30.
3 With an assistant holding the tensi oner in the required position, feed the accessory drive belt (3) over the
crankshaft pulley.
4 Slowly release the drive belt tensioner mechanism.
NOTE
Ensure the drive belt ribs are correctly aligned
with the grooves in the accessory drive pulleys or
damage to the drive belt and accessory drive
components and pulleys may occur.
5 Reinstall the air intake duct to the ai r flow meter and the throttle body, refer to Section 6C1-3 Engine Management
– V6 – Service Operations .
6 Run the engine to ensure correct operation.

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007