Yanmar 2TNV70 Service Manual page 133

Cylinder Block
• On an engine with high hours, the pistons rings
should be replaced and the cylinder honed
(See Honing and Boring on page 6-51) or
replaced. The piston should be replaced as
necessary.
9. Place each compression piston ring in the
groove as shown (Figure 6-67). 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 6-10
for specifications. Replace the piston if not
within specification.
Figure 6-67
10. To measure piston ring end gap, insert each
compression piston ring (Figure 6-68, (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 6-68, (2)) from the bottom of
the bore. Remove the piston. Measure the end
gap (Figure 6-68, (3)) of each piston ring.
Record the measurements. See Piston Ring on
page 6-10 for specifications.
TNV IDI Service Manual
Note: Always check the piston ring end gap
0001892
11. Repeat the above steps for each cylinder and
piston assembly.
Inspection of Connecting Rod
1. Measure the wrist pin bushing bore using a
bore gauge (Figure 6-69, (1)). Replace the
bushing if not within specifications. If the
bushing has been removed, measure the inside
diameter of the connecting rod small end
(Figure 6-69, (2)). Record the measurements.
See Connecting Rod on page 6-11 for
specifications.
Figure 6-68
when installing new piston rings. See
Piston Ring on page 6-10 for
specifications. Use a piston ring end gap
filing tool to adjust the piston ring end
gap on new piston rings.
ENGINE
(1)
(2)
(3)
0001964
6-47