Yanmar 4TNV98, Service Manual

Page: 125 / 246

4TNV98 & 4TNE98 Diesel Engine Section 3. Engine 123
NOTES
• On an engine with low hours, the pistons, piston
rings and cylinders may be reused if they are
found to be within specifications.
• On an engine with high hours, the pistons rings
should be replaced and the cylinder honed (see
Honing and Boring on page 126) or replaced.
The piston should be replaced as necessary.
9. Place each compression piston ring in the groove
as shown (Figure 6-114) . Use a feeler gauge to
measure the clearance between the piston ring
and the piston ring land. Record the
measurements. See Piston Ring on page 71 for
specifications. Replace the piston if not within
specification.
Figure 6-114
10. To measure piston ring end gap, insert each
compression piston ring (Figure 6-115, (1)) , one
at a time, into the cylinder. Use a piston with the
piston rings removed to slide the ring into the
cylinder bore until it is approximately 1.18 in. (30
mm)
(Figure 6-115, (2)) from the bottom of the
bore. Remove the piston. Measure the end gap
(Figure 6-115, (3)) of each piston ring. Record
the measurements. See Piston Ring on page 71
for specifications.
Figure 6-115
NOTE : Always check the piston ring end gap when
installing new piston rings. See Piston Ring on page
71 for specifications. Use a piston ring end gap
filing tool to adjust the piston ring end gap on new
piston rings.
11. Repeat the above steps for each cylinder and
piston assembly.