Page 4657 of 6020
MANUAL TRANSMISSION 7B1-51
TROUBLESHOOTING
1. ABNORMAL NOISE
1) NOISY IN NEUTRAL
Checkpoint Trouble Cause Countermeasure
Replenish or replace the gear
oilInsufficient or improper gear
oil
NG
Mainshaft splines
Synchronizer clutch hub
splinesReplace the main shaft and
the synchronizer clutch hub
Replace the gear(s)
Replace the flywheel pilot
W orn splines
W orn or scuffed gear tooth
contact surfaces
Flywheel pilot bearingW orn flywheel pilot bearing
Bearings (Mainshaft,
countershaft, and transfer
shaft)
Gears (Mainshaft,
countershaft, reverse idler
gear and transfer gears)
Replace the bearing(s)W orn or broken bearing(s)
OK NG
NG
NG
NG
OK
OK
OK
Gear oil
TransmissionRealign the transmissionTransmission misalignment
OK
NG
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ISUZU KB P190 2007
Page 4658 of 6020
7B1-52 MANUAL TRANSMISSION
2) NOISY OPERATION
Checkpoint Trouble Cause Countermeasure
Replenish or replace the gear
oilInsufficient or improper engine
oil
NG
Replace the gear(s)
Replace the gear(s)
Replace the bearing(s)
Gears (Gear whining)Lack of backlash between
meshing gears
Free running gears seizing on
the thrust face or the inner
face
Bearings (Hissing, thumping
or bumping)W orn or broken bearing(s)
Gears (Squealing at high
speeds)
Replace the gear(s)Gears (Growling, humming, or
grinding)W orn, chipped, or cracked
gear(s)
NG
NG
NG
NG
OK
OK
OK
OK
Gear oil (Metallic rattling)
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ISUZU KB P190 2007
Page 4659 of 6020
MANUAL TRANSMISSION 7B1-53
2. HARD SHIFTING
Checkpoint Trouble Cause Countermeasure
Change lever play
Clutch pedal free play
Repair or replace the
applicable parts and regrease
Readjust the clutch pedal free
play
W orn change lever sliding
portions
Improper clutch pedal free
play
Change lever operationRepair or regrease the change
lever assembly
Replenish or replace the
engine oil
Hard operating change lever
caused insufficient grease
Insufficient or improper gear
oil
OK
OK NG
NG
NG
NG
OK
OKGear oil
Continued on the next page
Shift rod and quadrant box
sliding faces, and other partsReplace the shidt rod and/or
the quadrant boxW orn shift rod and/or sliding
faces
Repair or replace the sleeveSleeve movement failure
NG
NG
OKShift block sleeve movement
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ISUZU KB P190 2007
Page 4660 of 6020
7B1-54 MANUAL TRANSMISSION
Checkpoint Trouble Cause Countermeasure
Synchronizer assembly
Shift arm and synchronizer
sleeve
Replace the worn parts
Replace the worn parts
W orn synchronizer parts
W orn shift arm and/or
synchronizer sleeve groove
Mainshaft and countershaft
thrust playReplace the worn partsW orn thrust washer, collar,
and/or gear thrust faces
OK NG
NG
NG
OK
OK
Continued from the previous
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ISUZU KB P190 2007
Page 4661 of 6020
MANUAL TRANSMISSION 7B1-55
3. WALKING OR JUMPING OUT OF GEAR
Checkpoint Trouble Cause Countermeasure
Shift rod and quadrant box
sliding faces
Detent ball
Replace the shift rod and/or
the quadrant box
Replace the detent ball
W orn shift rod and/or sliding
faces
W orn detent ball
Detent springRepair or replace the detent
spring
Replace the worn parts
Detent spring weak or broken
Insufficient stroke caused by
sliding position wear and
excessive play
OK
OK NG
NG
NG
NG
OK
OK
Change lever play
Continued on the next page
Mainshaft and countershaft
thrust playReplace the worn partsW orn thrust washer, collar,
and/or gear thrust faces
Replace the worn partsW orn shift arm and/or
synchronizer sleeve groove
NG
NG
OKShift arm and synchronizer
sleeve
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ISUZU KB P190 2007
Page 4662 of 6020
7B1-56 MANUAL TRANSMISSION
Checkpoint Trouble Cause Countermeasure
Synchronizer assembly
Bearings (Mainshaft,
countershaft, and individual
gears)
Replace the spring
Replace the bearing(s)
W eak or broken spring
W orn or broken bearings(s)
Mainshaft splines
Synchronizer clutch hub
splines
Replace the main shaft and
the synchronizer clutch hubW orn splines
OK NG
NG
NG
OK
OK
Continued from the previous page
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ISUZU KB P190 2007
Page 4663 of 6020
MANUAL TRANSMISSION 7B1-57
4. OIL LEAKAGE
Checkpoint Trouble Cause Countermeasure
Gear oilReplace the gear oilImproper gear oil
Drain plug and/or filler plugTighten the plug(s) and
replenish the oil
Drain the oil to the correct
level
Loose plug(s)
Oil level too high
OK NG
NG
NG
OK
OKOil level
Rear cover oil seal
Air breather
Replace the oil seal
Install the air breather
Replace the air breather
W orn or scratched oil seal
Air breather not installed
Air breather clogged
Front cover oil sealReplace the oil seal
Replace the gasket(s)
W orn or scratched oil seal
Defective or improperly
installed gasket(s)
OK NG
NG
NG
NG
OK
OKGaskets
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ISUZU KB P190 2007
Page 4664 of 6020
7B1-58 MANUAL TRANSMISSION
Special Tools (4×
××
×
2)
ILLUSTRATION TOOL NO.
TOOL NAME ILLUSTRATION
TOOL NO.
TOOL NAME
5-8840-2155-0
(J-37217)
Bearing remover 5-8840-2159-0
(J-37223)
Mainshaft end bearing installer
5-8840-2027-0
Puller 5-8840-0015-0
(J-22912-01) Bearing
remover/installer
5-8840-2160-0
(J-37224)
Holding fixture 5-8522-0050-0
(J-29769)
Rear case oil seal installer
5-8840-0003-0
(J-3289-20)
Holding fixture base 5-8840-0026-0
(J-26540)
Front cover oil seal installer
5-8840-2156-0
(J-37219)
Mainshaft nut wrench 9-8522-1165-0
(J-6133-01)
Mainshaft collar remover
5-8840-0047-0
(J-37225)
Tork bit wrench
(T– 45)
5-8840-2194-0
(J-35283)
Bearing installer
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ISUZU KB P190 2007