Yanmar 1GM User Manual page 122

116
CHAPTER SIX
2. Measure the ring gap with a feeler gauge as shown in
Figure 35. Compare the measurement with specifications
in Tables 1-3. If the measurement is not within specifica-
tion, the rings must be replaced as a set. Check the gap of
new rings as well. If the gap is too small, file the ends of
the ring to correct it (Figure 36).
3. Check the side clearance of the rings as shown in Fig-
ure 37. Place the feeler gauge alongside the ring all the
way into the groove. If the measurement is not within
specifications (Tables 1-3), either the rings or the ring
grooves are worn. Inspect and replace them as required.
4. Using a ring expander tool (Figure 38), carefully in-
stall the oil control ring, then the compression rings. The
oil ring consists oftwo pieces, the outer ring and the inner
expansion spring. Assemble the oil ring on the piston so
the expansion spring gap is on the opposite side ofthe pis-
ton from the ring end gap. See Figure 39. The second
compression ring is tapered while the top compression
ring has a barrel face. The top of each compression ring is
marked and must face toward the piston crown.
Connecting Rod Inspection
Have the connecting rod checked for straightness by a
dealer or machine shop.
The piston pin end of the connecting rod is equipped
with a bushing. Refer to Tables 1-3 for bushing specifica-
tions. Ifbushing replacement is required, a press is neces-
sary to remove the old bushing and install a new bushing.
The oil holes in the bushing and connecting rod must
align. Ream the bushing to obtain the desired clearance in
Tables 1-3.
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