Yanmar 1GM User Manual page 86

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Feeler gauge
3. Remove the cylinder head as described in this chapter.
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CHAPTER FIVE
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NOTE
Note the location ofthe long screw when re-
moving the oil pan retaining screws.
4. Remove the oil pan.
5. Rotate the crankshaft until the piston is at bottom dead
center. Pack the cylinder bore with clean shop rags. Re-
move the carbon ridge at the top ofthe cylinder bore with
a ridge reamer. These can be rented for use. Vacuum out
the shavings, then remove the shop rags.
6. Rotate the crankshaft until the connecting rod is cen-
tered in the bore. Measure the connecting rod side clear-
ance with a flat feeler gauge (Figure 30). If the clearance
exceeds specifications (Table 1), replace the connecting
rod during reassembly.
7. Remove the connecting rod bolts. Lift off the cap,
along with the lower bearing insert.
8. Use a wooden hammer handle to push the piston and
connecting rod from the bore.
9. Remove the piston rings with a ring remover (Figure
31).
Piston Pin Removal/Installation
The steel piston pin rides directly in the piston and the
connecting rod bushing. Circlips at each end retain the
piston pin in the piston.
1. Before removing the piston, place the crankshaft end
of the connecting rod in a vise with soft jaws. Rock the
piston as shown in Figure 32. Any rocking motion (do not
confuse with the normal sliding motion) indicates wear on
the piston pin, piston pin bore or connecting rod small end
bore (or a combination of these).