ISUZU KB P190 2007 Workshop Repair Manual

Engine Mechanical – V6 Page 6A1–212

CAUTION
Do not reuse the piston pin retainers.
2 Remove the piston pin retainers by using the removal access notch (1) in the side of the piston. Discard the
piston pin retainers.

Figure 6A1 – 382
3 Slide the piston pin (1) out of the piston (2). The piston will disconnect from the connecting rod.

Figure 6A1 – 383
Clean and Inspect
Piston Cleaning Procedure
CAUTION
Do not use a wire brush to clean any part of
the piston.
1 Clean the piston skirts and the pins with a suitable solvent.
2 Clean the piston ring grooves with a groove cleaner. Ensure the oil ring holes and slots are clean.

Safety glasses must be worn when using
compressed air.
3 Dry the piston with compressed air.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–213

Piston Inspection Procedure
1 Inspect the pistons for the following conditions:
• eroded areas at the top of the piston (1),
• piston pin retainer grooves for burrs (2),
• worn piston pin bores or worn piston pins (3),
• scuffed or damaged skirt coating (4),
• ring grooves for cracks, nicks or burrs that may
cause binding (5), and
• warped or worn ring lands.
2 Replace pistons that show any signs of damage or excessive wear.
Figure 6A1 – 384
Piston Measurement
1 Measure piston width using the following procedure:
a Using an outside micrometer, measure the width of the piston at 30 mm below the crown
top (1), at the thrust surfaces of the piston,
perpendicular to the piston pin centreline.
b Compare the measurement of the piston to its original cylinder by subtracting the piston width
from the cylinder diameter.
c Check your measurements with specifications, refer to 5 Specifications.
d If the clearance obtained through measurement is greater than the provided specifications and
the cylinder bores are within specification,
replace the piston.
Figure 6A1 – 385
2 Measure the piston pin bore to piston pin (2) clearances using the following procedure:
a Piston pin bores and pins must be free of varnish or scuffing.
b Use an outside micrometer (1) to measure the piston pin in the piston contact areas.
Figure 6A1 – 386

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–214

3 Using an inside micrometer, measure the piston pin
bore (1). Compare the result with the piston pin
diameter and piston pin to piston pin bore clearance
listed in the specifications, refer to 5 Specifications.
4 If the clearance is excessive, determine which piece is out of specification and replace as required.
5 Replace the piston if any of its dimensions are out of specification.
6 If the new piston does not meet clearance specifications, the cylinder block may need to be
oversized to 0.25 mm. There is only one size of
oversized pistons and rings available for service.
Figure 6A1 – 387
Piston Ring Measurement
1 Measure the piston ring end gap using the following procedure:
a Place the piston ring (1) in the area of the bore where the piston ring will travel, approximately 25 mm below
the deck surface. Ensure the ring is square with the
cylinder bore by positioning the ring with the piston
head.
b Measure the end gap of the piston ring with feeler gauges (2), refer to 5 Specifications.
c If the clearance exceeds the provided specifications, the piston rings must be replaced.
d Repeat the procedure for all piston rings.
Figure 6A1 – 388
2 Measure the piston ring side clearance using the following procedure:
a Roll the piston ring (1) entirely around the piston ring groove. If any binding is caused by the ring groove,
dress the groove with a fine file. If any binding is
caused by a distorted piston ring, replace the ring.
b W ith the piston ring on the piston, use feeler gauges (2) to check clearance at multiple locations.
c Compare the measurements with piston ring side clearance listed in the specifications, refer to 5
Specifications.
d If the clearance is greater than specifications, replace the piston rings.
Figure 6A1 – 389

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–215

3 There is a locating dimple (1) on the compression
rings. Install the compression rings with the dimple
facing up.
4 If the new ring does not reduce the clearance to the correct specification, install a new piston.
5 If the new piston does not meet clearance specifications, the cylinder block may need to be
oversized to 0.25 mm. There is only one size of
oversized pistons and rings available for service.
Figure 6A1 – 390


Connecting Rod Cleaning Procedure
1 Clean the connecting rods in solvent.

Safety glasses must be worn when using
compressed air.
2 Dry the connecting rod using compressed air.
3 Remove the connecting rod cap and clean the threads.
4 Remove the connecting rod bearing and discard. Never reuse a connecting rod bearing that has been used in a running engine.
Connecting Rod Visual Inspection Procedure
1 Inspect the piston pin bushing (4) for scoring or
damage.
2 Inspect the connecting rod beam (1) for twisting or bending.
3 Inspect the rod cap (2) for any nicks or damage caused by possible interference.
4 Inspect for scratches or abrasion on the rod bearing seating surface.
5 If the connecting rod bores contain minor scratches or abrasions, clean the bores in a circular direction with
a light emery paper.
6 Retain the original bolts (3) for preliminary assembly. They must be replaced for final assembly.
Figure 6A1 – 391

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–216

Connecting Rod Measurement Procedure
Piston Pin End
NOTE
Measurements of all components should be
taken with the components at normal room
temperature.
1 Using an outside micrometer (1), take two measurements of the piston pin (2) in the area of the
connecting rod contact.
Figure 6A1 – 392
2 Using an inside micrometer, measure the connecting rod piston pin bore (1).
3 Subtract the piston pin diameter from the piston pin bore.
4 Compare the clearance measurements listed in the specifications, refer to 5 Specifications.
5 If the clearance is excessive, replace the piston pin. If a new pin does not resolve the clearance problem,
replace the connecting rod.
Figure 6A1 – 393
Crankshaft Bearing End
NOTE
Measurements of all components should be
taken with the components at normal room
temperature.
1 Using an inside micrometer, measure the connecting rod crankshaft bearing bore (1).
2 Compare the bore measurements listed in the specifications, refer to 5 Specifications.
3 Replace the connecting rod if the bore is out of specification. Do not recondition the connecting rod.
Figure 6A1 – 394

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–217

Reassemble
Piston and Piston Pin
CAUTION
The arrow located on top of the piston must
point toward the front of the engine.
NOTE
The connecting rod is non-directional and may
be assembled/reassembled to the piston in
either direction.
1 Lubricate the piston pin (1) bores in the piston (2) and the connecting rod with clean engine oil.
2 Assemble the piston and piston pin to the connecting rod. Correctly orient the piston when reusing a
marked connecting rod.
3 Align the piston pin bore with the connecting rod pin bore.
4 Slide the piston pin into the piston and the connecting rod.
Figure 6A1 – 395
CAUTION
New piston pin retainers must be used.
Never reuse the piston pin retainers.
5 Install new piston pin retainers (1).
6 Ensure the piston pin retainers are fully seated in their grooves.
7 Repeat steps 1 to 6 for the remaining pistons.
Figure 6A1 – 396

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–218

Piston Ring
NOTE
The ends of the expander must be facing
toward the top of the piston.
1 Correctly orient the oil control ring expander (1) before installation.
Figure 6A1 – 397
2 Using a piston ring expander, install the oil control ring assembly using the following procedure:
3 Install the expander ring (3).
4 Install the two oil scraper rings (4). Expand the rings only enough to clear the piston diameter. Over-
expanding the piston rings will distort or crack the
rings.
5 Install the second (2) and top (1) piston rings as follows.
Figure 6A1 – 398
6 Using the ring expander (1), install the second piston ring (2) onto the piston (3). Do not over-expand the
ring. Repeat for the top ring.
Figure 6A1 – 399

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–219

7 Once the rings are installed, set the ring gaps for the
oil control, second and top ring as follows. Use the
piston location arrow for reference.
• Lower oil control ring position (1).
• Upper oil control ring position (2).
• Top ring position (3).
• Oil control ring expander position (4).
• Second ring position (5).
Figure 6A1 – 400
Connecting Rod Bearing
CAUTION
If the connecting rod bearings have been
used in a running engine, they must be
replaced with new connecting rod bearings
for reassembly.
1 Clean the connecting rod (2) and the connecting rod cap bearing bore with a lint-free cloth.
2 Clean the oil from behind the connecting rod bearing halves.
3 Install a new upper connecting rod bearing (1) into position. Roll the bearing into position so the lock tang
engages the alignment slot. The bearing must fit flush
in the connecting rod.
Figure 6A1 – 401
4 Install the lower connecting rod bearing (1) into position in the connecting rod cap (2).
5 Roll the bearing into position so the lock tang engages the alignment slot. The bearing must fit flush
with the connecting rod cap.
Figure 6A1 – 402

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–220

Reinstall
Piston Connecting Rod and Connecting Rod Bearing Installation
CAUTION
The piston is directional and must be
installed in the engine block in the correct
direction. The locating arrow on the top of
each piston must be pointing toward the
front of the engine.
1 Liberally lubricate the cylinder walls, piston rings and piston skirts with engine oil.
2 Select the correctly numbered piston/connecting rod assembly for the cylinder. A dot (1) showing correct
piston orientation is located on the top of the piston.
Figure 6A1 – 403
3 Install connecting rod guide pin set, Tool No. EN-46121 (1) into the connecting rod bolt holes.
Figure 6A1 – 404
4 Compress the piston rings using a commercially available ring compressor.
CAUTION
Extreme care must be used when installing
the piston and connecting rod to ensure the
rod does not scrape or nick the cylinder
bore, oil jets, or crankshaft surfaces.
5 Using both hands from the top and bottom of the cylinder, slowly guide the piston (2) and connecting
rod assembly into the cylinder. Do not allow the
connecting rod to contact the cylinder wall.
6 W hen the ring compressor contacts the deck surface, gently tap the piston into the cylinder using the handle
end of a dead-blow hammer. Guide the connecting
rod onto the crankshaft bearing journal using
connecting rod guide pin set, Tool No. EN-46121 (1)
while gently tapping the piston into the cylinder with a
soft-blow hammer.
Figure 6A1 – 405

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Engine Mechanical – V6 Page 6A1–221

7 Remove connecting rod guide pin set, Tool No.
EN-46121 (1) from the connecting rod bolt holes.
Figure 6A1 – 406
Connecting Rod Bearing Clearance Measurement Procedure
NOTE
Before final assembly, check the clearance of the
new connecting rod bearings.
1 Place a length of fresh, room temperature plastic gauging material all the way across the connecting
rod bearing journal.
2 Install the connecting rod bearing into the connecting rod cap.
3 Install the connecting rod end cap (1) on its original connecting rod and ensure the bearing lock tangs are
aligned on the same side of the rod.
Figure 6A1 – 407
NOTE
Reuse the old connecting rod bolts only for
measuring the connecting rod bearing clearance.
4 Install the connecting rod cap bolts into the connecting rod cap and tighten to the correct torque specification using torque angle wrench, Tool No. EN-7115.
Connecting rod cap attaching
bolt torque specification:
Stage 1 .........................30.0 Nm
Stage 2 ........ Loosen completely
Stage 3 .........................25.0 Nm
Stage 4 .................. 110 degrees
5 Allow the assembly to sit for at least 2 minutes.
6 Remove the connecting rod cap bolts and discard.
7 Remove the connecting rod cap.

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