Yanmar 3TNV82A Service Manual page 195

Crankshaft and Camshaft Components
Note: 3TNV82A - 4TNV88: The oil pump is
driven directly by flats on the crankshaft
drive gear hub.
Measuring Idler Gear-to-Crankshaft Gear
Backlash
1. Install a dial indicator as shown in Figure 6-87.
Figure 6-87
2. Rotate the idler gear back and forth to check
the idler gear-to-crankshaft gear backlash. The
total indicator reading is the backlash. Record
the measurement.
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)).
TNV DI Service Manual
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
0002086
not remove the camshaft gear unless it or the
camshaft is damaged and requires
replacement. See Removal of Camshaft on
page 6-71.
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 6-89, (3))
retaining the pump drive gear to the hub. Only
remove the nut (Figure 6-89, (1)) and washer
(Figure 6-89, (2)), leaving the hub attached to
the gear. Remove the pump drive gear and hub
as an assembly using a gear puller.
ENGINE
(2)
(3)
0001728A
Figure 6-88
CAUTION
0000031en
(1)
6-69