engine ISUZU TROOPER 1998 Service Repair Manual

6A Ð 26 ENGINE MECHANICAL
8. Crankshaft Rear Oil Seal
·With the oil seal pushed in deep, install the special
tool as shown in the illustration and remove the oil
seal.
Oil Seal Remover : 5-8840-2362-0
9. Crankcase Assembly
·Refer to ÒCrankcaseÓ in Section 6A2.
10. Oil Pump Assembly
11. Piston Cooling Oil Pipe
12. Piston and Connecting Rod Assembly
13. Main Bearing Cap
14. Crankshaft
INSPECTION AND REPAIR
Make the necessary adjustments, repairs, and part replacements if excessive wear or damage is discovered
during inspection.
1. Crankshaft
Thrust clearance
Set the dial indicator as shown in the illustration and
measure the crankshaft thrust clearance.
If the thrust clearance exceeds the specified limit, re-
place the thrust bearing as a set.
Standard Limit
mm(in)
0.10 (0.0039) 0.30 (0.0118)
167 (17/123)N·m(kg·m/lb·ft)
2. Main bearing clearance
1) Remove the main bearing caps in the sequence
shown in the illustration
Arrange the removed main bearing caps in the
cylinder number order.
2) Remove the crankshaft. Remove the main
bearings.
3) Clean the upper and lower bearings as well as the
crankshaft main journal.
4) Check the bearings for damage or excessive wear.
The bearings must be replaced as a set if damage
or excessive wear is discovered during inspection.
5) Set the upper bearings and the thrust washers to
their original positions. Carefully install the
crankshaft.
6) Set the lower bearings to the bearing cap original
position.
7) Apply plastigage to the crankshaft journal unit as
shown in the illustration.
8) Install the main bearing caps. Apply engine oil to
the bolt threads and the seats. Tighten the bolts
to the specified torque.

ENGINE MECHANICAL 6A Ð 27
NOTE:
Do not allow the crankshaft to rotate.
9) Remove the main bearing caps.
10) Measure the plastigage width and determine the
oil clearance. If the oil clearance exceeds the
specified limit, replace the main bearings as a set
and/or replace the crankshaft.
11) Clean the plastigage from the bearings and the
crankshaft.
Remove the crankshaft and the bearings.
3. Run-out
1) Carefully set the crankshaft on the V-blocks.
Slowly rotate the crankshaft and measure the
runout. If the crankshaft runout exceeds the
specified limit, the crankshaft must be replaced.
Measure the diameter and the uneven wear of
main journal and crank pin.
If the crankshaft wear exceeds the specified limit,
crankshaft must be replaced.
Standard Limit
mm(in.)
0.031 – 0.063
(0.0012 – 0.0025)0.11 (0.0043)
Standard Limit
mm(in)
0.05 (0.0020)
or less0.08 (0.0031) Run-Out
Standard Limitmm(in)
Main journal
diameter69.91
(2.7524)
69.917-69.932
(2.7526-2.7532)
Crank pin
diameter52.90
(2.0843) 52.915-52.930
(2.0833-2.0839)
Uneven
wear limit
0.05
(0.0020)
or less
0.08
(0.0031)

6A Ð 28 ENGINE MECHANICAL
Crankshaft inspection
Inspect the surface of the crankshaft journals and crank
pins for excessive wear and damage.
Inspect the oil seal fitting surfaces for excessive wear and
damage.
Inspect the oil ports for obstructions.
Crankshaft tufftriding inspection
The portion to be tested must be held horizontally so as
not to let the test solution flow.
Test liquid should not be applied to the area around the
oil port.
The sliding surface of the pin or journal.
Approximately 10mm
NOTE:
To increase crankshaft strength,Tufftride Method (Soft
nitriding) has been applied. Because of this, it is not
possible to regrind the crankshaft surfaces.
1. Use an organic cleaner to thoroughly clean the crank-
shaft. There must be no traces of oil the surfaces to be
inspected.
2. Prepare a 5 - 10% solution of ammonium cupric chloride
(dissolved in distilled water).
3. Use a syringe to apply the solution to the surface to be
inspected.
Hold the surface to be inspected perfectly horizontal to
prevent the solution from running.
NOTE:
Do not allow the solution to come in contact with the oil
ports and their surrounding area.
Testing
1. Wait for thirty to forty seconds.
If there is no discoloration after thirty or forty seconds,
the crankshaft is usable.
If discoloration appears (the surface being tested will
become the color copper), the crankshaft must be re-
placed.
2. Steam clean the crankshaft surface immediately after
completing the test.
NOTE:
The ammonium cupric chloride solution is highly corrosive.
Because of this, it is imperative that the surfaces being
tested be cleaned immediately after completing the test.

ENGINE MECHANICAL 6A Ð 29
Crankshaft Bearing Selection
When installing new crankshaft bearings or replacing old
bearings, refer to the selection table below.
Select and install the new crankshaft bearings, paying close
attention to the cylinder body journal hole 1 diameter size
mark and the crankshaft journal 2 diameter size mark.
Crankshaft Bearing Housing Grade Mark Position
Crankshaft bearing housing grade marks 1 or 2 are
stamped on the rear right hand side of the cylinder body.
Example:
Crankshaft Journal Grade Mark Position
The crankshaft journal grade marks (1 or Ð) are stamped on
each crankshaft journal web.
The crankshaft journal and bearing clearance must be the
same for each position after installation of the crankshaft
and the crankshaft bearings.
Note:
The crankshaft journal mark No. 4 is stamped on crankshaft
No. 4 journal web front side or rear side.
NOTE:
Although all upper journal bearings (cylinder body side)
have oil grooves and holes, all lower bearings (bearing
cap side) have no groove and hole.
Play close attention to the distinction during the installa-
tion procedure.
Main Bearing
Bore Diameter mm(in.)Crankshaft
Main Journal Diameter mm(in.)
Size Mark Inside DiameterGrade Mark Outside Diameter
Crankshaft
Bearing
Grade Mark
Oil Clearance
mm (in.)
1 or - 69.927 ~ 69.932
(2.7530 ~ 2.7532)
2 or - -69.922 ~ 69.927
(2.7528 ~ 2.7530)
3 or - - -69.917 ~ 69.922
(2.7526 ~ 2.7528)
1 or -69.927 ~ 69.932
(2.7530 ~ 2.7532)
2 or - - 69.922 ~ 69.927
(2.7528 ~ 2.7530)
3 or - - -69.917 ~ 69.922
(2.7526 ~ 2.7528)Black
Blue
Green
Black 73.987 ~ 74.000
(2.9129 ~ 2.9134)
73.975 ~ 73.987
(2.9124 ~ 2.9129) 1
20.035 ~ 0.061
(0.0014 ~ 0.0024)
0.032 ~ 0.058
(0.0013 ~ 0.0023)
0.037 ~ 0.063
(0.0015 ~ 0.0025)
0.031 ~ 0.056
(0.0012 ~ 0.0022)
0.036 ~ 0.048
(0.0014 ~ 0.0019)
0.033 ~ 0.058
(0.0013 ~ 0.0023)
No. 1 Bearing
HousingNo. 2 Bearing
HousingNo. 3 Bearing
HousingNo. 4 Bearing
HousingNo. 5 Bearing
Housing
12112

6A Ð 30 ENGINE MECHANICAL
REASSEMBLY
14. Crankshaft
·Install the main bearings to the cylinder body and
the main bearing caps.
·Be sure that they are positioned correctly.
·Apply new engine oil to the upper and lower main
bearing faces.
·Carefully mount the crankshaft.
·Apply engine oil to the thrust washer.
·Assemble the thrust washer to the No. 3 bearing
journal. The oil grooves must face the crankshaft.
13. Main Bearing Cap
·Apply the recommended liquid gasket or its equiva-
lent to the No. 5 crankshaft bearing cap 1 as shown
in the illustration.
·Install the arch gasket 2 to the No. 5 bearing cap.
Use your fingers to push the arch gasket into the
bearing cap groove.
NOTE
Take care not to scratch the arch gasket outer surface.
·Apply the recommended liquid gasket or its equiva-
lent to the No. 5 crankshaft bearing cap cylinder
body fitting surfaces at points 3 and 4 shown in the
illustration.
NOTE:
Be sure that the bearing cap fitting surface is completely
free of oil before applying the liquid gasket.
Do not allow the liquid gasket to obstruct the cylinder
thread holes and bearings.

ENGINE MECHANICAL 6A Ð 31
·Install the bearing caps with the bearing cap head
arrow mark facing the front of the engine.
·Apply engine oil to the crankshaft bearing cap bolts.
·Tighten the crankshaft bearing cap bolts to the
specified torque a little at a time in the sequence
shown in the illustration.
NOTE:
Check to see that the crankshaft turns smoothly by rotating
it manually.
12. Piston and Connecting Rod Assembly
·Apply engine oil to the cylinder bores, the connect-
ing rod bearings and the crankshaft pins and each
piston ring and piston.
Check to see that the piston ring end gaps are
correctly positioned.
29 (3.0/22)
N·m(kg·m/lb.ft) Oiling Jet Plug
10. Oil Pump Assembly
1) Prepare a solution of 80% engine oil and 20%
molybdenum disulfide.
2) Apply an ample coat of the solution to the teeth of
the oil pump pinion.
3) Install the oil pump and tighten the bolts to the
specified torque.After tightening the cap nuts, check to see that the
crankshaft rotates smoothly.
11. Piston Cooling Oil Pipe
·Tighten the bolt and oiling jet plug to the specified
torque ·Insert the piston/connecting rod assemblies into
each cylinder with the piston ring compressor.
Piston ring compressor: 5-8840-9018-0
The front marks must be facing the front of the
engine.
·Match the numbered caps with the numbers on the
connecting rods. Align the punched marks on the
connecting rods and caps.
·Apply engine oil to the threads and seating faces of
the nuts.
·Tighten the cap nuts in 2 steps, using angular tight-
ening method as shown in the following specifica-
tions.
167 (17.0/123)N·m(kg·m/lb·ft)
N·m (kg·m/lb·ft)
45¡ ~ 60¡ 1st step 2nd step
29 (3.0/22)
N·m (kg·m/lb·ft)
19 (1.9/14) M6 8 (0.8/6)
M8

6A Ð 32 ENGINE MECHANICAL
19 (1.9/14)N·m(kg·m/lb·ft)
5. Timing Gear Case
1) Install the timing gear case to the cylinder body.
NOTE:
Take care not to twist the front oil seal.
6. Flywheel
1) Thoroughly clean and remove the oil from the
threads of crankshaft.
2) Mount the flywheel on the crankshaft and then
install the washer.
3) Align the flywheel with the crankshaft dowel pin.
4) Tighten the flywheel bolts to the specified torque
in the numerical order shown in the illustration.
82 (8.4/61)N·m(kg·m/lb·ft)
NOTE:
Take care not to damage the O-rings when tightening the
oil pipe bolts.
9. Crankcase Assembly
·Refer to ÒCrankcaseÓ Section 6A2
8. Crankshaft Rear Oil Seal
1) Tighten the adapter to the crankshaft rear and
section with 2 bolts.
2) Insert the oil seal into the peripheral section of the
adapter,
3) Insert the sleeve into the adapter section, and 1)
tighten it with a bolt (M12 x 1.75L = 70) until the
adapter section hits the sleeve.
4) Remove the adapter and the sleeve.
5) With the seal pressed in, check the dimension of
the oil seal section.
Standard Dimension = 12.5 ± 0.3 mm
Oil Seal Installer: 5-8840-2359-0
7. Cylinder Block Rear Plate
Align the rear plate with the cylinder body knock pins.
Tighten the rear plate to the specified torque.
118 (12.0/87)N·m(kg·m/lb·ft)

ENGINE MECHANICAL 6A Ð 33
2) Tighten the timing gear case bolt together with
the timing gear case gasket to the specified
torque.
19 (1.9/14)N·m(kg·m/lb·ft)
3) Cut away the gasket protruding above the fitting
surfaces (as shown in the illustration).
4. Crankshaft Front Oil Seal
·Use the installer to install the front oil seal 1 to
the gear case cover 2.
Oil Seal Installer: 5-8840-2061-0
Note the oil seal installation depth 3 shown in
the illustration.
Depth 3 = 1 mm (0.0394 in.)
3. Crankshaft Timing Gear
Use the crankshaft timing gear installer 1 to install the
timing gear 2.
The crankshaft timing mark (ÒX Ð XÓ) must be facing
outward.
Crankshaft Timing Gear Installer: 5-8522-0024-0
2. Camshaft Timing Gear
·Tighten the fixing bolt to the specified torque.
64 (6.5/47)N·m(kg·m/lb·ft)
1. Cylinder Head
·Refer to ÒCylinder headÓ in Section 6A2.

6A Ð 34 ENGINE MECHANICAL
PISTON AND CONNECTING ROD
DISASSEMBLY
1. Cylinder Head Assembly
·Refer to ÒCylinder headÓ in Section 6A2.
2. Crankcase Assembly
·Refer to ÒCrankcaseÓ in Section 6A2
3. Oil Pump Assembly
4. Connecting Rod Bearing Cap
5. Piston and Connecting Rod
·Remove carbon deposits from the upper portion
of the cylinder wall with a scraper before
removing the piston and connecting rod

ENGINE MECHANICAL 6A Ð 35
6. Piston Ring
Remove the piston rings with a piston ring expander.
Arrange the removed piston rings in the cylinder
number order.
7. Piston Pin Snap Ring
·Use a pair of pliers to remove the piston pin snap
rings
8. Piston Pin
NOTE:
Keep the parts removed from each cylinder separate. All
parts must be reinstalled in their original positions.
9. Piston
10. Connecting Rod
INSPECTION AND REPAIR
PISTON AND PISTON RING
Pistons
Carefully clean away all the carbon adhering to the piston
head and the piston ring grooves.
NOTE:
Never use a wire brush to clean the pistons. Damage will
result.
Visually check each piston for cracking, scoring, and other
signs of excessive wear.
If any of the above conditions are present, the piston
must be replaced.
Piston Diameter
1. Measure the piston outside diameter with micrometer
at the piston grading position.
71.00 (2.7974)
mm(in) Piston Grading Position