Yanmar 4TNE98, Service Manual

Page: 96 / 246

4TNV98 & 4TNE98 Diesel Engine Section 3. Engine 94
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
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.
Figure 6-51
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.
Figure 6-52