Yanmar 4TNV98 Service Manual page 115

Measuring Idler Gear-to-Camshaft Gear Backlash
1. Drive a small wooden wedge between the
crankshaft gear and idler gear to prevent the idler
gear from rotating.
2. Install the dial indicator to read the camshaft gear
backlash. Rotate the camshaft drive gear against
the idler gear to measure the backlash. Record
the measurement.
3. Check the idler gear-to-fuel injection pump drive
gear backlash in the same manner as the
camshaft drive gear. Record the measurement.
Removal of Timing Gears
1. Remove the bolts from the idler gear shaft
(Figure 6-88, (1)). Remove the idler gear shaft,
idler gear (Figure 6-88, (2)) and bushing (Figure
6-88, (3)).
Figure 6-88
2. Do not remove the crankshaft gear unless it is
damaged and requires replacement. If the gear
must be removed, remove it using a gear puller.
3. Removal of the camshaft gear requires the
camshaft be removed and placed in a press. Do
not remove the camshaft gear unless it or the
camshaft is damaged and requires replacement.
See Removal of Camshaft on page 114.
4TNV98 & 4TNE98 Diesel Engine
Do not loosen or remove the four bolts retaining
the fuel injection pump drive gear to the fuel
injection pump hub. Do not disassemble the fuel
injection pump drive gear from the hub. Correct
fuel injection timing will be very difficult or
impossible to achieve.
4. Do not remove the fuel injection pump drive gear
unless absolutely necessary to avoid damage to
the gear or pump. Do not loosen or remove the
four bolts (Figure 115, (3)) retaining the pump
drive gear to the hub. Only remove the nut (Figure
6-89, (1)) and washer (Figure 115, (2)), leaving
the hub attached to the gear. Remove the pump
drive gear and hub as an assembly using a gear
puller.
4TNV98 Engine
Removal of Oil Pan
1. Invert the engine (oil pan up) on the engine stand.
2. Remove the oil pan (Figure 116, (1)).
113
CAUTION
Figure 6-89
Section 3. Engine