Yanmar 4TNV98 Service Manual page 96

Figure 6-49
Rocker Arm Shaft Outside Diameter
Use a micrometer to measure the rocker arm shaft
diameter (Figure 6-50). Measure at each rocker arm
location in two directions 90° apart (Figure 6-50).
See Rocker Arm and Shaft on page 68 for the
service limit.
Figure 6-50
4TNV98 & 4TNE98 Diesel Engine
Inspection of Valve Guides
Valve Guide Inside Diameter
Visually inspect the valve guides for distortions,
scoring or other damage.
NOTE : Measure the valve guides while they are
installed in cylinder head.
Use a telescoping gauge and micrometer to
measure the inside diameter at each end of the
valve guide. Measure in three places and 90° apart
(Figure 6-51). See Intake/Exhaust Valve and Guide
on page 67 for the service limit. Replace the valve
guides if not within specification.
Inspection of Cylinder Head
Cylinder Head Distortion
Place the cylinder head flat and inverted
(combustion side up) on the bench. Use a straight
edge and feeler gauge to measure cylinder head
distortion (Figure 6-52). Measure diagonally and
along each side. See Cylinder Head on page 66 for
the service limit.
94
Figure 6-51
Figure 6-52
Section 3. Engine