Yanmar 4TNV98, Service Manual

Page: 109 / 246

4TNV98 & 4TNE98 Diesel Engine Section 3. Engine 107
7. Tighten the lock nut (Figure 6-80, (1)) , while
holding the valve bridge (Figure 6-80, (3)) with a
wrench (Figure 6-80, (2)) . Verify that the valve
clearance (Figure 6-81, (2) is zero “0”.
Figure 6-80
Figure 6-81
NOTE : There is a tendency for the clearance to
decrease slightly when the lock nut is tightened. It is
suggested that you make the initial clearance
adjustment is made slightly on the “loose” side
before tightening the lock nut.
8. To adjust the actual valve clearance between the
rocker arm and the valve bridge, insert a feeler
gauge
(Figure 6-82, (1)) of the correct thickness
(See Adjustment Specifications on page6-6)
between the rocker arm
(Figure 6-82, (2)) and
valve bridge (Figure 6-82, (3)) . Record the results
and use this value as an indication of wear.
Figure 6-82
9. If adjustment is required, proceed to the next step.
10. Loosen the valve adjusting screw lock nut
(Figure 6-83, (5)) and valve adjusting screw
(Figure 6-83, (4)) on the rocker arm (Figure 6-83,
(3)) and check the clearance gap (Figure 6-83,
(2)) for evidence of dirt or wear.
NOTE : There is a tendency for the clearance to
decrease slightly when the lock nut is tightened. It is
suggested that you make the clearance adjustment
is made slightly on the “loose” side before tightening
the lock nut.
11. Adjust the valve clearance (Figure 6-83, (2)) by
turning the adjusting screw (Figure 6-83, (4))
until there is a slight “drag” on the feeler gauge
when sliding it between the rocker arm and the
valve bridge.