Yanmar 4TNV98 Service Manual page 114

Figure 6-85
Checking Timing Gear Backlash
Prior to removing the timing gears, measure the
gear backlash and determine the gear wear.
Check the backlash between each pair of mating
gears (Figure 6-86). If not within specification,
replace both mating gears. See Timing Gear
Backlash on page 69 for service limits.
NOTE: Do not allow the gear being checked to
move axially as excess end play could cause a false
reading.
4TNV98 & 4TNE98 Diesel Engine
(1) Fuel Injection Pump Drive Gear.
(2) Camshaft Drive Gear.
(3) Auxiliary Drive Gear (Optional).
(4) Crankshaft Drive Gear.
(5) Direction of Rotation.
(6) Oil Pump Drive Gear (4TNV94L - 4TNV106).
(7) Idler Gear.
Measuring Idler Gear-to-Crankshaft Gear
Backlash
1. Install a dial indicator as shown in 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.
112
Figure 6-86
Figure 6-87
Section 3. Engine