Isuzu N-Series. Manual - part 488
Engine Mechanical (4HK1-TC) 6A-57
9. Check if the rocker arm shaft is worn.
• Use a micrometer to measure 8 places rubbed
by the rocker arms.
• Replace the shaft if the diameter is less than
the limit.
10. Inspect a clearance between the rocker arm and
the rocker arm shaft.
• Use a cylinder gauge to measure an inside
diameter of the bush of the rocker arm to
measure a clearance between the external
diameter of the shaft.
• If the measurement exceeds the limit, replace
the rocker arm and the shaft.
11. Inspect a clearance between the roller of the
rocker arm and the rocker arm pin.
a. Pass a string, through the opening between the
rocker arm and the roller, pull it strongly in the
direction indicated with arrows and measure
the gap between the rocker arm and the roller
with the roller being hulled out. (Figure 1)
b. After marking the measuring point, pull the
string out push the roller fully into the rocker
arm, and measure the gap of the marked place.
(Figure 2)
c. The gap between the measurement taken
under a. and that under b. Is the a clearance
between the roller and the rocker arm pin. If it
exceeds the limit, replace the rocker arm.
Bend of the rocker arm shaft
mm (in)
Limit
0.3 (0.012)
External diameter of the rocker arm shaft
mm (in)
Standard
21.979 – 22.000 (0.865 – 0.866)
Limit
21.85 (0.860)
N6A6087E
N6A6088E
Clearance between the rocker arm and
rocker arm shaft
mm (in)
Standard
0.010 – 0.056 (0.0004 – 0.0022)
Limit
0.2 (0.0079 )
Clearance between the roller and the
rocker arm pin
mm (in)
Standard
0.068 – 0.100 (0.0026 – 0.0039)
Limit
0.2 (0.0079)
N6A6089E