Yanmar 4TNV98, Service Manual

Page: 117 / 246

4TNV98 & 4TNE98 Diesel Engine Section 3. Engine 115
2. Remove the two bolts (Figure 6-94, (3)) retaining
the camshaft thrust plate (Figure 6-94, (1)) .
Figure 6-94
3. Rotate the engine in the engine stand so that
gravity causes the tappets (Figure 6-94, (5)) to
drop away from the camshaft lobes.
NOTE : Rotate the camshaft at least two turns to
“bump” any sticking tappets away from the camshaft.
4. Slowly pull the camshaft (Figure 6-94, (2))
assembly out of the engine being careful not to
damage the front camshaft bushing.
NOTE : If the engine is not installed on an engine
repair fixture, stand the engine upright on the
flywheel end mounting flange. Rotate the camshaft
at least two turns to bump the tappets out of the way
to prevent the tappets from interfering with the
removal of the camshaft.
NOTE : The tappets are “mushroom” shaped and
must be removed from inside the engine crankcase.
5. Remove the tappets. Mark the tappets so they
can be reinstalled in the same location.
6. Remove the camshaft drive gear (Figure 6-94,
(4)) only if the gear or camshaft require
replacement. Use a knife-edge puller and a press
to remove the gear. The gear is a shrink-fit and
will need to be heated to 356° - 392°F (180° -
200°C) to remove.
Removal of Gear Case or Front Plate
NOTE : The camshaft must be removed before the
gear case / front plate can be removed. See
Inspection of Camshaft on page 125.
1. Remove the oil pump.
NOTE : It is not necessary to remove the fuel
injection pump from the gear case / front plate to
remove the gear case / front plate. If the fuel
injection pump does not need to be repaired, leaving
it mounted to the timing gear case / front plate will
eliminate the need to re-time it during assembly. See
Fuel Injection Pump on page 141.
2. Remove the bolts (Figure 6-95, (4)) .
3. Remove the gear case (Figure 6-95, (1)) or front
plate from the cylinder block. Thoroughly clean all
old sealant from the mating surfaces.
4. Inspect and measure the camshaft bushing.
See Camshaft on page 68 for the service limit. If
damaged or worn beyond service limits, remove
the camshaft bushing
(Figure 6-95, (3)) .
5. Remove two O-rings (Figure 6-95, (2)) .
Figure 6-95