ISUZU TROOPER 1998 Service Repair Manual

6A– 78 ENGINE MECHANICAL
Crankshaft Bearing Bore Grade Mark Position
Crankshaft bearing bore grade marks
1or 2are
stamped on the rear right hand side of the cylinder
body.
Example:
No. 1 Bearing No. 2 Bearing No. 3 Bearing No. 4 Bearing No. 5 Bearing
Housing Housing Housing Housing Housing
Legend
(1) No. 1 Main bearing bore grade
(2) No. 2 Main bearing bore grade
(3) No. 3 Main bearing bore grade
(4) No. 4 Main bearing bore grade
(5) No. 5 Main bearing bore gradeCrankshaft Journal Grade Mark Position
The crankshaft journal grade marks (1 or –) are
stamped on each crankshaft journal wave.
The crankshaft journal and bearing clearance must be
the same for each position after installation of the
crankshaft and the crankshaft bearings.
Legend
(1) Crankshaft journal outside diameter grade
12112
1
11122 234 5
1
2
3
4
5
012RW114
1
015RW078
012RW069

ENGINE MECHANICAL 6A– 79
Main Bearing Crankshaft
Bore Diameter mm(in) Main Journal Diameter mm(in)Crankshaft Oil Clearance
Grade Inside Diameter Grade Outside DiameterBearing mm(in)
1 or - 69.927 – 69.932 4 0.045 – 0.061
(2.7530 – 2.7532) (0.0018 – 0.0024)
1 73.992 – 74.000 2 or - - 69.922 – 69.927 4 0.050 – 0.066
(2.9131 – 2.9134) (2.7528 – 2.7530) (0.0020 – 0.0026)
3 or - - - 69.917 – 69.922 5 0.052 – 0.068
(2.7526 – 2.7528) (0.0020 – 0.0027)
1 or - 69.927 – 69.932 2 0.042 – 0.059
(2.7530 – 2.7532) (0.0017 – 0.0023)
2 73.983 – 73.992 2 or - - 69.922 – 69.927 3 0.044 – 0.061
(2.9127 – 2.9131) (2.7528 – 2.7530) (0.0017 – 0.0024)
3 or - - - 69.917 – 69.922 4 0.046 – 0.063
(2.7526 – 2.7528) (0.0018 – 0.0025)
1 or - 69.927 – 69.932 1 0.037 – 0.053
(2.7530 – 2.7532) (0.0015 – 0.0021)
3 73.975 – 73.983 2 or - - 69.922 – 69.927 2 0.039 – 0.055
(2.9124 – 2.9127) (2.7528 – 2.7530) (0.0015 – 0.0022)
3 or - - - 69.917 – 69.922 2 0.044 – 0.060
(2.7526 – 2.7528) (0.0017 – 0.0024)
REASSEMBLY
1. Crankshaft
1) Install the main bearings to the cylinder body
and the main bearing caps.
2) Be sure that they are positioned correctly.
3) Apply new engine oil to the upper and lower
main bearing faces.
4) Carefully mount the crankshaft.
5) Apply engine oil to the thrust washer.
6) Assemble the thrust washer to the No. 3 bearing
journal. The oil grooves must face the
crankshaft.7) Install the bearing caps with the bearing cap
head arrow mark facing the front of the engine.
8) Apply engine oil to the crankshaft bearing cap
bolts.
9) Tighten the crankshaft bearing cap bolts to the
specified torque a little at a time in the sequence
shown in the illustration.
Torque: 167 N·m (17.0 kg·m/123 lb ft)
NOTE: Check to see that the crankshaft turns smoothly
by rotating it manually.
012RW047
84159
610
23
7
012RW027

6A– 80 ENGINE MECHANICAL
3. Piston and Connecting Rod Assembly
1) Apply engine oil to the cylinder bores, the
connecting rod bearings and the crankshaft pins
and each piston ring and piston.
2) Align the front mark (2) of piston and front mark
(3) of connecting rod then assemble them.
3) The N mark of the piston ring is faced toward the
top, check to see that the piston ring end gap is
correctly positioned.
Legend
(1) 1st piston ring end gap
(2) 2nd piston ring end gap
(3) Oil ring end gap4) Insert the piston/connecting rod assemblies into
each cylinder with the piston ring compressor.
The front marks must be facing the front of the
engine.
Piston Ring Compressor: 5-8840-9018-0
5) Match the numbered caps with the numbers on
the connecting rods. Align the punched marks
on the connecting rods and caps.
6) Apply engine oil to the threads and seating faces
of the nuts.
7) Tighten the cap nuts in 2 steps, using angular
tightening method as shown in the following
specifications.
1st step: 29 N·m (3.0 kg·m/22 lb ft)
2nd step: 45°– 60°
After tightening the cap nuts, check to see that
the crankshaft rotates smoothly
4. Piston Cooling Oil Pipe
If the piston cooling oil pipe is forcibly assembled,
the end of the oil jet may bend. It could make it
impossible to supply oil to the piston cooling holes,
which will sometimes cause piston seizure.
Sufficient care should be taken to pipe assembly
work.
1) Tighten the bolt and oil jet plug to the specified
torque.
Torque:
M6: 8 N·m (0.8 kg·m/6 lb ft)
M8: 20 N·m (2.0 kg·m/14.5 lb ft)
Oiling Jet Plug: 30 N·m (3.1 kg·m/22 lb ft)
5. Crank case
1) Refer to “Crank case” in this manual.
6. Apply liquid gasket (TB-1207C or equivalent) to
retainer then install it to rear end of cylinder block
within 5 minutes.
7. 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 and tighten it
with a bolt (M12 x 1.75L = 70) until the adapter
hits the sleeve.
4) Remove the adapter and the sleeve.
5) Check the dimension of the oil seal setting from
rear end of crankshaft.
Standard Dimension = 12.5 ± 0.3 mm
Oil Seal Installer: 5-8840-2359-0
2
3
1
015RW051
3
1
2
015RW083

ENGINE MECHANICAL 6A– 81
8. Cylinder Block Rear Plate (A/T)
Align the rear plate with the cylinder block dowel
pins.
Tighten the rear plate to the specified torque.
Torque: 97 N·m (9.9 kg·m/72 lb ft)
9. Flywheel housing (M/T)
Align the flywheel housing with the cylinder block
dowel pins.
Tighten the bolt to the specified torque.
Torque: 97 N·m (9.9 kg·m/72 lb ft)
10. Flywheel
1) Thoroughly clean and remove the oil from the
threads of crankshaft and flywheel fixing
surface.
2) Mount the flywheel on the crankshaft and then
install the washer.
3) Align the timing mark, cut out on the flywheel is
at lowest position for M/T model and
identification hole on the boss is highest position
for A/T model when cylinder No. 1 is at the TDC.
For M/T ModelFor A/T model
4) Tighten the flywheel bolts in 2 steps using
angular tightening method.
Torque: 1st step 60 N·m (6.1 kg·m/44 lb ft)
Torque: 2nd step 60°– 90°
11. Timing Gear Case
1) Cut away the gasket protruding between the
cylinder block and the crank case fitting surfaces
(as shown in the illustration).
12.5 + 0.3–
012RW067
Timing mark
278
74
015RW121
Timing mark
74304
015RW120
751
3
8
6 2 4
201RW021

6A– 82 ENGINE MECHANICAL
2) Apply liquid gasket (TB1207B or equivalent)
between the cylinder block and the crankcase
fitting surfaces.
3) Install the timing gear case to the cylinder body.
4) Tighten the timing gear case bolt together with
the timing gear case gasket to the specified
torque.
Torque: 20 N·m (2.0 kg·m/14.5 lb·ft)
12. Crankshaft Gear
1) Set key to crankshaft key groove.
2) The timing mark on the crankshaft gear must be
facing outward.
3) Use the crankshaft gear installer to install the
crankshaft gear.
Crankshaft installer: 9-8522-0021-0
Legend
(1) Crankshaft Gear Installer
(2) Crankshaft Gear13. Installation of the Timing Gear
1) Align teeth on the scissors gear and lock them
before install timing gear.
2) Align timing marks on each timing gear and
assemble them.
3) Refer to timing gear detail in this manual.
14. Timing Gear Case Cover
1) Remove lock bolt from idle gear A and remove
lock pin from idle gear C.
2) Install oil pump gear oil seal before assembling
timing gear case cover.
3) Clean fitting surface and apply liquid gasket
(TB1207C or equivalent) to fitting surface.
4) Tighten bolts to specified torque.
Torque: 20 N·m (2.0 kg·m/14.5 lb ft)
12
2
012RW066
2
2~2.5mm
2~2.5mm
Apply liquid gasket around inside
of the bolt hole
Bolt hole
Inside
Outside
F06HX00001
012RW024
012RW064

15. Crankshaft Front Oil Seal
1) Set oil seal with special tool.
2) Install front oil seal to timing gear case cover.
Crankshaft Front Oil Seal Installer: 5-8840-2061-0
3) Remove special tool and check oil seal position
from front surface of timing gear case.
Oil Seal Position: 0.5 – 2.5 mm (0.0197 –0.0984 in)
16. Cylinder Head
1) Refer to “Cylinder head” in this manual.
ENGINE MECHANICAL 6A– 83
015RW074

6A– 84 ENGINE MECHANICAL
PISTON AND CONNECTING ROD
5
8
7
3
1
2 6
4
012RW061
Legend
(1) Cylinder Head Assembly
(2) Crank Case
(3) Connecting Rod Bearing Cap(4) Connecting Rod
(5) Piston Ring
(6) Piston Pin
(7) Piston Pin Snap Ring
(8) Piston

ENGINE MECHANICAL 6A– 85
DISASSEMBLY
1. Cylinder Head Assembly
1) Refer to “Cylinder head” in this manual.
2. Crank Case Assembly
1) Refer to “Crank Case” in this manual.
3. Connecting Rod Bearing Cap
4. Piston and Connecting Rod
1) Remove carbon deposits from the upper portion
of the cylinder wall with a scraper before
removing the piston and connecting rod.
5. Piston Ring
Remove the piston rings with a piston ring
expander.
Arrange the removed piston rings in the cylinder
number order.
6. Piston Pin Snap Ring
1) Use a pair of pliers to remove the piston pin
snap rings.7. Piston Pin
1) Remove piston pin from piston assembly.
NOTE: Keep the parts removed from each cylinder
separate. All parts must be reinstalled in their original
positions.
8. Piston
9. 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.
Piston Grading Position: 69.75 mm (2.7461 in)
from piston head
Piston Outside Diameter mm(in)
Grade Mark Outside Diameter
A 95.320 – 95.329 (3.7527 – 3.7531)
B 95.330 – 95.339 (3.7531 – 3.7535)
C 95.340 – 95.349 (3.7535 – 3.7539)
015RW082
015RW077
015LV014

6A– 86 ENGINE MECHANICAL
Legend
(1) Piston Grade
(2) Piston Front Mark
(3) Part Number
The grade for piston outside diameter is stamped
on the piston head.
Measure the cylinder bore diameter at measuring
points.
If the piston clearance does not conform to the
specified value, the pistons most be replaced.
Piston Clearance:
0.092 – 0.110 mm (0.0036 – 0.0043 in)
Cylinder Bore Diameter mm(in)
Grade Mark Cylinder Bore Diameter
A 95.421 – 95.430 (3.7567 – 3.7571)
B 95.431 – 95.440 (3.7571 – 3.7575)
C 95.441 – 95.450 (3.7575 – 3.7579)Legend
Measuring point 1 = 20 mm
2 = 90 mm
3 = 160 mm
Piston rings
Any worn or damaged part discovered during engine
overhaul must be replaced with a new one.
1. Ring end gap measurement
1) Insert the piston ring into the cylinder bore.
2) Push the ring by the piston, at the right angle to
the wall, into the point at which the cylinder bore
diameter is the smallest.
3) Measure the ring end gap.
NOTE: The piston ring is stamped with a discerning
mark on the upper face of piston ring.
1
3
2
015RW080
012RW071
321
012RW117
012RW051

ENGINE MECHANICAL 6A– 87
Discerning Mark
Piston Ring Discerning Mark
1st compression ring 1N
2nd compression ring 2N
Ring End Gap mm(in)
Piston Ring Standard Gap Limit
1st 0.25 –0.40
compression ring (0.0098 – 0.0157)
2nd 0.20 –0.35 1.5
compression ring (0.0079 – 0.0138) (0.0590)
Oil ring0.10 –0.30
(0.0039 – 0.0118)
2. Measure the clearance between the piston ring
groove and the piston ring with a feeler gauge. If the
piston ring groove/piston ring clearance exceeds
the specified limit, the piston and/or piston rings
must be replaced.
mm(in)
Standard Limit
1st0.05 – 0.09
Compression (0.0020 – 0.0035)
ring
2nd0.05 – 0.09 0.15
(0.0020 – 0.0035) (0.0059)
Oil ring0.03 – 0.07
(0.0012 – 0.0028)Piston pin
Visually inspect the piston pin for cracks, flaws, and
other damage and replace if necessary.
1. Use a micrometer to measure the piston pin outside
diameter in both directions at three different
positions. If the measurement exceeds the
specified limit, the piston pin must be replaced.
Standard: 30.995 – 31.000 mm (1.2212 – 1.2214 in)
Limit: 30.97 mm (1.2202 in)
N
012RW037015RW076
012RW082