4TNV98 & 4TNE98 Diesel Engine Section 3. Engine112Figure 6-85Checking Timing Gear BacklashPrior to removing the timing gears, measure thegear backlash and determine the gear wear.Check the backlash between each pair of matinggears (Figure 6-86). If not within specification,replace both mating gears. See Timing GearBacklash on page 69 for service limits.NOTE: Do not allow the gear being checked tomove axially as excess end play could cause a falsereading.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 GearBacklash1. Install a dial indicator as shown in Figure 6-87.Figure 6-872. Rotate the idler gear back and forth to check theidler gear-to-crankshaft gear backlash. The totalindicator reading is the backlash. Record themeasurement.
