Yanmar 4TNV98, Service Manual

Page: 114 / 246

4TNV98 & 4TNE98 Diesel Engine Section 3. Engine 112
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.
Figure 6-86
(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 .
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.