Yanmar 1GM User Manual page 97

SINGLE-CYLI ND ER ENGINES
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3. Remove the drive disc (Figure 68).
4. Gradua lly loosen and remove the flywh eel bolts,
working in a diagonal pattern. Install two drive disc bolts
into two outer holes in the flywheel (Figure 69), then use
the screws to pull and remov e the flywheel.
5. Inspect the ring gear. If the ring gear is excessively
worn or damaged, usc the following procedure to remove
the ring gear:
a. Heat the ring gear evenly, then drive the ring gear
off the flywhee l.
b. Heal the ring gear prior to installation. Drive the
ring gear onto the flywheel, being careful not to
damage the gear teeth.
6. Reverse the removal procedure to install the flywheel.
Tigh ten the flywheel retaining bo lts to the torque speci-
fied in Ta ble 2. Refer to Chapter Ten to install the drive
disc and transm ission.
DRIVE DISC
Refer to Chapter Ten for drive disc procedures (Figur e
68).
CRANKSHA FT
Rem ova l a nd In stallation
Refer to Fig ure 70.
1. Remove the flywheel as previous ly described.
2. Remove the bellhousing (A, Figure 71).
3. Remove the piston and connecting rod as previously
described.
4. Remove the oil pump as previously described.
5. Remove the crankshaft gear (F igure 72).
6. Refer to Camshaft to remove the camshaft gear.
7. Remove the thrust washer (F igure 73) and thrust bear-
ing (Figure 74).
NOTE
Support the crankshaft while removing the
main bearing housing in the next step.
8. Remove the main bearing housing (8, Fig ure 71) .
9. Remove the crankshaft.
10. Proceed as follows to replace the crankshaft seal in
the main bearing hous ing :
a. Pry the old seal from the main bearing housing with
a large screwd river. Work carefully to prevent dam-
age to the main bearing hous ing seal surface.
b. Clean the seal recess in the housin g with solvent
and dry with compressed air.
c. Apply gasket sealer to the periphery of the sea l.
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