ISUZU TF SERIES 2004 Workshop Manual

ENGINE MECHANICAL 6A – 61

INSPECTION AND REPAIR
Make the necessary adjustments, repairs, and part replacements if excessive wear or damage is discovered during
inspection.




CYLINDER HEAD
Cylinder Head Lower Face Warpage
1. Use a straight edge and a feeler gauge to measure the
four sides and the two diagonals of the cylinder head lower
face.
2. The cylinder head lower surface warpage is more than the
limit, it should be replaced.


Cylinder Head Lower Face Warpage mm (in)
Standard Limit
0.05
(0.002) or less 0.20
(0.0079)


NOTE:
The cylinder head lower face cannot be reground.

Cylinder Head Height (
H) (Reference) mm (in)
Standard
91.95 – 92.05
(3.620 – 3.624)




Positive Crankcase Ventilation (PCV) Valve
1. Remove PCV valve assembly from cylinder head cover.
2. Inspect the diaphragm for broken.
3. Inspect the spring for broken or weaken.
4. If find any abnormal condition, replace the PCV valve
assembly.

011RY00012
011RY00013
011RY00014

6A – 62 ENGINE MECHANICAL






















Manifold Fitting Face Warpage
Use a straight edge and a feeler gauge to measure the
manifold cylinder head fitting face warpage.
Regrind the manifold cylinder head fitting surfaces if the
measured values are greater than the specified limit but less
than the maximum grinding allowance.
If the measured values exceed the maximum grinding
allowance, the cylinder head must be replaced.


Manifold Fitting Face Warpage
mm (in)
Standard Limit Maximum Grinding
Allowance
0.05
(0.002) or less 0.20
(0.008) 0.40
(0.016)



















Exhaust Manifold Warpage
Use a straight edge and a feeler gauge to measure the
manifold cylinder head fitting face warpage.
If the measured values exceed the specified limit, the manifold
must be replaced.


Exhaust Manifold Warpage mm (in)
Standard Limit
0.05 (0.002) or less 0.20 (0.008)



























Valve Stem and Valve Guide Clearance
Measuring Method-I
1. With the valve stem inserted in the valve guide, set the dial
indicator needle to "0".
2. Move the valve head from side to side.
Read the dial indicator.
Note the highest dial indication.
If the measured values exceed the specified limit, the valve
and the valve guide must be replaced as a set.


Valve Stem Clearance mm (in)
Standard Limit
Intake Valve 0.039 - 0.071
(0.0015 - 0.0028) 0.200
(0.008)
Exhaust Valve 0.064 - 0.096
(0.0025 - 0.0038) 0.250
(0.0098)
027RY00001
027RY00002
011RY00022

ENGINE MECHANICAL 6A – 63


Measuring Method-II
1. Measure the valve stem outside diameter.
Refer to the Item "Valve Stem Outside Diameter".
2. Use a caliper calibrator or a telescoping gauge to measure
the valve guide inside diameter.













Valve Guide Replacement
Valve Guide Removal
Use a hammer and the valve guide replacer to drive out the
valve guide from the cylinder head lower face.
Valve Guide Replacer: 9-8523-1212-0













Valve Guide Installation
1. Apply engine oil to the valve guide outer circumference.
2. Attach the valve guide installer to the valve guide.
3. Use a hammer to drive the valve guide into position from
the cylinder head upper face.
Valve Guide Replacer: 9-8523-1212-0











4. Measure the height of the valve guide upper end from the
upper face of the cylinder head.


Valve Guide Upper End Height (H) (Reference) mm (in)
12.8-13.2 (0.50-0.52)
NOTE:
If the valve guide has been removed, both the valve
and the valve guide must be replaced as a set.

011LX029
011RY00024
011RY000025011RY00023

6A – 64 ENGINE MECHANICAL














Valve Stem Outside Diameter
Measure the valve stem diameter at three points.
If the measured value is less than the specified limit, the valve
and the valve guide must be replaced as a set.


Valve Stem Outside Diameter mm (in)
Standard Limit
Intake Valve 7.946 - 7.961
(0.3128 - 0.3134) 7.880
(0.3102)
Exhaust Valve 7.921 - 7.936
(0.3119 - 0.3124) 7.850
(0.3090)

















Valve Thickness
Measure the valve thickness.
If the measured value is less than the specified limit, the valve
and the valve guide must be replaced as a set.


Intake and Exhaust Valve Thickness mm (in)
Standard Limit
4JA1T (L) 1.8 (0.07) 1.5 (0.06)
Inlet 1.34 (0.054) 4JA1TC,
4JH1TC
Exhaust 1.36 (0.055) 1.1 (0.045)




















Valve Depression
1. Install the valve (1) to the cylinder head (2).
2. Use a depth gauge or a straight edge with steel rule to
measure the valve depression from the cylinder head lowe
r
surface.
If the measured value exceeds the specified limit, the valve
seat insert must be replaced.


Valve Depression mm (in)
Standard Limit
4JA1T(L) 0.72 (0.029) 1.28 (0.050)
4JA1TC, 4JH1TC 1.17 (0.048) 1.67 (0.068)

011LX027
014RY00020
014RY00021

ENGINE MECHANICAL 6A – 65
















Valve Contact Width
1. Check the valve contact faces for roughness and
unevenness. Make smooth the valve contact surfaces.
2. Measure the valve contact width.
If the measured value exceeds the specified limit, the valve
seat insert must be replaced.


Valve Contact Width mm (in)
Standard Limit
Intake 1.7 (0.067) 2.2 (0.087)
Exhaust 2.0 (0.079) 2.5 (0.078)
























Valve Seat Insert Replacement
Valve Seat Insert Removal
1. Arc weld the entire inside circumference (1) of the valve
seat insert (2).
2. Allow the valve seat insert to cool for a few minutes.
This will invite contraction and make removal of the valve
seat insert easier.
3. Use a screwdriver (3) to pry the valve seat insert free.
Take care not to damage the cylinder head (4).
4. Carefully remove carbon and other foreign material from
the cylinder head insert bore.


014RY00027
011LX039

6A – 66 ENGINE MECHANICAL


Valve Seat Insert Installation
1. Carefully place the attachment (1) (having a smaller
outside diameter than the valve seat insert) on the valve
seat insert (2).

NOTE:
The smooth side of the attachment must contact the
valve seat insert.

2. Use a bench press (3) to gradually apply pressure to the
attachment and press the valve seat insert into place.

NOTE:
Do not apply an excessive amount of pressure with
the bench press. Damage to the valve seat insert will
result.








Valve Seat Insert Correction
1. Remove the carbon from the valve seat insert surface.
2. Use a valve cutter (15
, 45
, and 75
blades) to minimize
scratches and other rough areas. This will bring the
contact width back to the standard value.
Remove only the scratches and rough areas. Do not cut
away too much. Take care not to cut away unblemished
areas of the valve seat surface.









Valve Seat Angle Degree
45
NOTE:
Use an adjustable valve cutter pilot.
Do not allow the valve cutter pilot to wobble inside the
valve guide.











3. Apply abrasive compound to the valve seat insert surface.
4. Insert the valve into the valve guide.
5. Turn the valve while tapping it to fit the valve seat insert.
6. Check that the valve contact width is correct.
7. Check that the valve seat insert surface is in contact with
the entire circumference of the valve.



011LX063 014RY00026
011LX037
011LX038

ENGINE MECHANICAL 6A – 67













Valve Spring Free Height
Use a vernier caliper to measure the valve spring free height.
If the measured value is less than the specified limit, the valve
spring must be replaced.


Spring Free Height mm (in)
Standard Limit
4JA1T (L)
4JA1TC,
4JH1TC Single spring 48.0 (1.89) 47.1 (1.85)
















Valve Spring Squareness
Use a surface plate and a square to measure the valve spring
squareness.
If the measured value exceeds the specified limit, the valve
spring must be replaced.


Spring Squareness mm (in)
Limit
4JA1T (L)
4JA1TC,
4JH1TC Single spring 1.7 (0.070)

















Valve Spring Tension
Use a spring tester to measure the valve spring tension.
If the measured value is less than the specified limit, the valve
spring must be replaced.


Valve Spring Tension N (kg/lb)
Compressed
Height Standard Limit
4JA1T (L)
4JA1TC,
4JH1TCSingle
spring38.9mm
(1.53in) 296.0
(30.2/66.4) 257.7
(26.3/57.9)

011LX024
014RY00025
011LX026

6A – 68 ENGINE MECHANICAL






























ROCKER ARM SHAFT AND ROCKER ARM
Rocker Arm Shaft Run-Out
1. Place the rocker arm shaft on a V-block.
2. Use a dial indicator to measure the rocker arm shaft
central portion run-out.
If the run-out is very slight, correct the rocker arm shaft
run-out with a bench press. The rocker arm must be at cold
condition.
If the measured rocker arm shaft run-out exceeds the
specified limit, the rocker arm shaft must be replaced.


Rocker Arm Shaft Run-Out mm (in)
Limit
0.3 (0.012)
















Rocker Arm Shaft Outside Diameter
Use a micrometer to measure the rocker arm fitting portion
outside diameter.
If the measured value is less than the specified limit, the rocker
arm shaft must be replaced.


Rocker Arm Shaft Outside Diameter mm (in)
Standard Limit
18.98–19.00 (0.747–0.748) 18.90 (0.744)












Rocker Arm Shaft and Rocker Arm Clearance
1. Use either a vernier caliper or a dial indicator to measure
the rocker arm inside diameter.


Rocker Arm Inside Diameter mm (in)
Standard Limit
19.010–19.030
(0.748–0.749) 19.100 (0.752)









2. Measure the rocker arm shaft outside diameter.
If the measured value exceeds the specified limit, replace
either the rocker arm or the rocker arm shaft.


Rocker Arm Shaft and Rocker Arm Clearance mm (in)
Standard Limit
0.01–0.05
(0.0004–0.0020) 0.20 (0.008)
015LX009
014RY00024015LX008

ENGINE MECHANICAL 6A – 69
3. Check that the rocker arm oil port is free of obstructions.
If necessary, use compressed air to clean the rocker arm
oil port.




Rocker Arm Correction
Inspect the rocker arm valve stem contact surfaces for step
wear (1) and scoring (2).
If the contact surfaces have light step wear or scoring, they
may be honed with an oil stone.
If the step wear or scoring is severe, the rocker arm must be
replaced.



CYLINDER BODY
Cylinder Body Upper Face Warpage
1. Remove the cylinder body dowel.
2. Remove the cylinder liner.
Refer to "Cylinder Liner Replacement".
















3. Use a straight edge (1) and a feeler gauge (2) to measure
the four sides and the two diagonals of the cylinder body
upper face.
If the measured values exceeds the limit, the cylinder body
must be replaced.


Cylinder Body Upper Face Warpage mm (in)
Standard Limit
0.05 (0.002) or less 0.20 (0.008)


Cylinder Body Height (H) (Reference) mm (in)
Standard
4JA1T(L), 4JA1TC : 244.945-245.055 (9.6435-9.6478)
4JH1TC : 269.945-270.055 (10.6277-10.6320)
4. Reinstall the cylinder liner.
Refer to "Cylinder Liner Replacement".
5. Reinstall the cylinder body dowel.


014RY00024
012R100001
012RY00009014RY00023

6A – 70 ENGINE MECHANICAL





















Cylinder Liner Bore Measurement
Use a cylinder indicator to measure the cylinder bore at
measuring point (1) in the thrust (2-2) and axial (3-3) directions
of the crankshaft.
Measuring Point (1): 20 mm (0.79 in)
If the measured value exceeds the specified limit, the cylinder
liner must be replaced.


Cylinder Liner Bore mm (in)
Standard Limit
4JA1T(L), 4JA1TC 93.00 (3.6614) 93.08 (3.6646)
4JH1TC 95.40 (3.7559) 95.48 (3.7590)
NOTE:
The inside of the dry type cylinder liner is chrome
plated. It cannot be rebored or honed.
If the inside of the cylinder liner is scored or
scorched, the cylinder liner must be replaced.




















Cylinder Liner Projection Inspection
1. Hold a straight edge along the top edge of the cylinder liner
to be measured.
2. Use a feeler gauge to measure each cylinder liner
projection.


Cylinder Liner Projection mm (in)
Standard
0-0.1 (0-0.004)
The difference in the cylinder liner projection height
between any two adjacent cylinders must not exceed 0.03
mm (0.0012 in).













Cylinder Liner Replacement
Cylinder Liner Removal
1. Insert the cylinder liner remover (1) into the cylinder body
(from the lower side of the cylinder body) until it makes firm
contact with the cylinder liner.
Cylinder Liner Remover : 5-8840-2039-0 (4JA1L/TC)
: 5-8840-2304-0 (4JH1TC)
2. Use a bench press (2) to slowly force the cylinder liner
from the cylinder body.


NOTE:
Take care not to damage the cylinder body upper face
during the cylinder liner removal procedure.
3. Measure the cylinder body upper face warpage.
Refer to "Cylinder Body Upper Face Warpage".
012RY00010
012LX016
012RY00012