ENGINE MECHANICAL 6A – 67
VALVE CLEARANCE ADJUSTMENT
NOTE:
1. Valve clearance should be inspected and adjusted
while the engine is cool.
2. The tightening of the camshaft bearing cap and
camshaft carrier assembly should be checked
before inspecting and adjusting valve clearance.
INSPECTION
1. Remove cylinder head noise insulator cover and
cylinder head cover.
Refer to “Cylinder Head” in this manual.
2. Disconnect all harness connecters of the injector
and remove harness assembly.
3. Drain oil from oil rail assembly.
4. Remove injector clamp nuts and fixing bolts to take
out injector assembly.
5. Loosen oil rail bolts, remove oil rail assembly.
6. Set cylinder No.1 to the TDC at the compression
stroke. Make sure that there is play in cylinder No.1
tappets on inlet and exhaust sides and that there is
no play in cylinder No.4 tappets.
7. Measure valve clearance at No.1 TDC (Refer to the
black circles indicated in the illustration).
Standard Valve clearance:
Intake valve: 0.15 mm (0.0059 in) ± 0.05 mm (0.0020 in)
Exhaust valve: 0.25 mm (0.0098 in) ± 0.05 mm (0.0020 in)
8. Turn the crankshaft one turn to set No.4 cylinder
TDC at the compression stroke.
9. Measure valve clearance at No.4 TDC (Refer to the
black circles indicated in the illustration).
Standard Valve clearance:
Intake valve: 0.15 mm (0.0059 in) ± 0.05 mm (0.0020 in)
Exhaust valve: 0.25 mm (0.0098 in) ± 0.05 mm (0.0020 in)
10. If measured value is outside standard value,
readjust the valve clearance.
ADJUSTMENT
For valve clearance adjustment, follow the procedure
given below.
1. Set cylinder No.1 or No.4 to the TDC at the
compression stroke.
Set the valve clearance adjusting tool on the tappet
requiring adjustment.
After making sure of the correct setting of the
special tool, depress the tappet by turning the bolt.
Valve Clearance Adjusting Tool: 5-8840-2590-0
NOTE: Before depressing the tappet, set the tappet
notch in the direction where adjuster can be easily
taken out.
2. Take out the adjuster using a small screw driver and
finger magnet.
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ENGINE MECHANICAL 6A – 75
DISASSEMBLY
1. Cylinder Head
1) Refer to “Cylinder head” in this manual.
2. Crankshaft Front Oil Seal
1) Use a plastic hammer and a screwdriver to tap
around the oil seal to free it from the gear case
cover.
Take care not to damage the oil seal fitting
surfaces.
3. Crankshaft Timing Gear
4. Timing Gear Case
5. Flywheel
6. Cylinder Block Rear Plate
7. Crankshaft Rear Oil Seal
1) Use special tool to remove the crankshaft rear
oil seal.
Oil Seal Remover: 5-8840-2360-0
8. Crank Case
9. Piston Cooling Oil Pipe
10. Piston and Connecting Rod Assembly
11. Main Bearing Cap Assembly
12. 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,
replace the thrust bearing as a set.
Standard : 0.04 – 0.20 mm (0.0016 – 0.0079 in)
Limit: 0.30 mm (0.0118 in)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.
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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 Nꞏm (17.0 kgꞏm/123 lb ft)
NOTE: Check to see that the crankshaft turns smoothly
by rotating it manually.
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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 Nꞏm (3.0 kgꞏm/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 Nꞏm (0.8 kgꞏm/6 lb ft)
M8: 20 Nꞏm (2.0 kgꞏm/14.5 lb ft)
Oiling Jet Plug: 30 Nꞏm (3.1 kgꞏm/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
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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
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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)
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6A – 88 ENGINE MECHANICAL
2. Measure the inside diameter of the connecting rod
small end. If the clearance between the small end
and pin does not conform to the specified value, the
connecting rod or bushing and pin must be
replaced.
Standard: 0.008 – 0.020 mm (0.0003 – 0.0008 in )
Limit: 0.05 mm (0.0020 in)
3. Insert the piston pin into the piston and rotate it. If
the pin rotates smoothly with no backlash, the
clearance is normal. If there is backlash or
roughness, measure the clearance. If the clearance
exceeds the specified limit, the piston and the
piston pin must be replaced.
Standard: 0.005 – 0.018 mm (0.0002 – 0.0007 in )
Limit: 0.04 mm (0.0016 in)
Bushing replacement
Removal: Use a suitable bar and bench press or
hammer
Installation: Align the bushing with a connecting rod
oil port. After installing a new bushing,
finish the bushing bore with a pin hole
grinder.Connecting rods
1. Check the connecting rod alignment with a
connecting rod aligner.
If either the bend or the twist exceeds the specified
limit, the connecting rod must be replaced.
Bend per 100 mm (3.937 in)
Standard: 0.08 mm (0.0031 in) or less
Limit: 0.20 mm (0.0079 in)
Twist per 100 mm (3.937 in)
Standard: 0.05 mm (0.0020 in) or less
Limit: 0.15 mm (0.0059 in)
2. Measure the connecting rod thrust clearance.
Use a feeler gauge to measure the thrust clearance
at the big end of the connecting rod.
If the clearance exceeds the specified limit, the
connecting rod must be replaced.
Standard: 0.230 mm (0.0091 in)
Limit: 0.350 mm (0.0138 in)
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ENGINE MECHANICAL 6A – 89
3. Measure the oil clearance between the connecting
rod and the crankshaft.
1) Remove the connecting rod cap nuts and the
rod caps.
Arrange the removed rod caps in the cylinder
number order.
2) Clean the rod bearings and the crankshaft pins.
3) Carefully check the rod bearings.
If even one bearing is found to be damaged or
badly worn, the entire bearing assembly must be
replaced as a set. Reinstall the bearings in their
original positions.
Apply plastigage to the crank pin.
4) Reinstall the rod caps to their original positions.
5) Tighten the cap nuts in 2 steps, using angular
tightening method as shown in the following
specifications.
1st step: 29 Nꞏm (3.0 kgꞏm/22 lb ft)
2nd step: 45°– 60°NOTE: Do not allow the crankshaft to rotate
6) Remove the rod caps.
7) Measure the smallest width of the plastigage
and determine the oil clearance. If the oil
clearance exceeds the limit, replace the rod
bearings as a set.
8) Clean the plastigage from the bearings and the
crankshaft pins
Standard: 0.022 – 0.042 mm (0.0009 – 0.0017 in)
Limit: 0.100 mm (0.0039 in)
REASSEMBLY
1. Connecting Rod
2. Piston
3. Piston Pin
1) Apply a coat of engine oil to the piston pin and
the piston pin hole.
4. Piston Pin Snap Ring
1) Try to insert the piston pin into the piston pin
hole with normal finger pressure.
2) Weight each piston and connecting rod
assembly.
3) Select piston and connecting rod combinations
so that the weight variation of the different four
assemblies is held within the specified limits.
Variance in weight after assembly: Less than 3g
(0.1058 oz)
NOTE: When changing piston/connecting rod
combinations, do not change the piston/piston pin
combination.
4) Attach the piston to the connecting rod with the
piston front mark (2) and the connecting rod
front mark (3) on the same side.
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