TM 5-3895-346-14
IDLER GEAR
ENGINE OVERHAUL
An idler gear bearing with two oil grooves has been incorporated in the idler gear and bearing assemblies,
beginning with engine serial number 4D-9458.
When a new bearing (bushing) is installed in the idler gear, it must not protrude beyond the gear face on either
side and must sustain an axial load of 2000 pounds (9. 07 kN) minimum without pushing out of the gear.
Install Idler Gear and Beariug Assembly
1. Place the inner thrust washer on the forward end of the idler gear hub with the flat in the inner
diameter of the thrust washer over the flat on the end of the gear hub and with the oil grooves in the thrust
washer facing the idler gear.
2. Place the small protruding end of the idler gear hub through the end plate and into the counterbore in
the cylinder block.
3. Insert two 3/8-16 bolts through the idler gear hub and thread them into the cylinder block, as shown in
Fig. 1, to be sure the boltholes will be in alignment when the flywheel housing is installed.
4. Insert the 3/8-16 x 1-3/4-inches long special bolt through the center of the idler gear hub and thread it
into the cylinder block. Tighten the bolt to 40-45 lb ft (54-61 Nm) torque. Then remove the two 3/8-16 bolts
previously installed for alignment of the gear hub.
5. Lubricate the idler gear hub and idler gear bearings liberally with clean engine oil.
6. Position the crankshaft gear and the camshaft gear or balance shaft gear so that their timing marks
will align with those on the idler gear.
7. With these timing marks in alignment, install the idler gear as shown in Fig. 2.
8. Apply a thin film of cup grease to the inner face (face with the oil grooves) of the outer idler gear
thrust washer. Then place the thrust washer over the end of the idler gear hub with the oil grooves in the side
of the thrust washer facing the idler gear, and the flat in the inner diameter of the thrust washer over the flat on
the end of the idler gear hub.
9. Check the backlash between the mating gears. The backlash should be 0.003 to 0.005 inch between
new gears and should not exceed 0.007 inch between used gears.
Figure 2. Installing Idler Gear
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