Onan MJA Series Service Manual page 90

88 ENGINE DISASSE MB L Y
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3.9.4 CAJ\1SHAFT
The camshaft is a I-piece mr-chine forging, driven through gears by the
crankshaft.
It
rides on sleeve bearings pressed into the crankcase,
In addition
to
opening and closing the valves. the camshaft operates the
fuel pump and. on MJC plants. drives the distributor.
3.9.4.1 Removal. ­
1. Remove the rocker arms and pushrods from the valve chambers.
2. Remove the fuel pump from the engine.
3.
On
MJC, remove the distributor, Sect 3.3.
4. Remove the crankshaft gear retaining washer by removing the lock
ring on the crankshaft.
5. Lay the engine on side to avoid dropping tappets and remove the
camshaft assembly as a group.
If
necessary, pry it out using a
screwdriver between the camshaft gear and crankcase.
6. Remove the push rod tappets. These can be removed only from the
camshaft end of the pushrod holes.
3.9. 4.2 Repair. -
If
a lobe has become slightly scored, dress it
smooth with a fine stone. If the camshaft is badly worn or scored, re­
place
it.
For information about the center pin, see Sect 3.9 3.
3. 9.4.3 Camshaft Gear. - This gear is a pressed fit· on the camshaft
.and drives
it
at
1/2
the crankshaft speed. The camshaft gear drives the
ignition timing (start-disconnect switch on 4 cylinder) gear on 2 cylinder
models. To remove the gear, use a hollow tool or pipe that will fit in ­
side the gear bore and over the center pin. Press the camshaft out of
the gear bore. Be careful not to damage the center pin.
P € S -5
REAR
BEARING
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9
32 - 16
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II
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CEN,ER
BEARING
PRESS BEAR1N
F"LUSHWITH
FRONT CRANK.­
CASE SURFACE
LlGNOIL
HOLES
FRON
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8EARIN
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FIG 3. 9.E - CAMSHAFT BEARING INSTALLATION
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