DETROIT DIESEL 53
1.7.4 Idler Gear
Fig, 3 Idler Gear Details and Relative Location of Parts
through the end plate and into the counterbore in the
the cylinder block. Then remove the idler gear hub
cylinder block.
and the idler gear inner thrust washer as an assembly.
3. Insert two 3/8 "-16 bolts through the idler gear hub
and thread them into the cylinder block, as shown in
Inspection
Fig. I, to be sure the bolt holes will be in alignment
when the flywheel housing is installed.
Wash the idler gear and bearing assembly, hub and
thrust washers thoroughly in clean fuel oil and dry
4. Insert the 3/8"-16x1-3/4" special bolt through the
them with compressed air. Examine the gear teeth and
center of the idler gear hub and thread it into the
bearing for scoring, pitting and wear. If the gear teeth
cylinder block. Tighten the bolt to 40-45 lb-ft torque.
are worn or the bearing is scored, pitted or worn
Then remove the two 3/8 "-16 bolts previously
excessively, replace the gear and bearing assembly or
Installed for alignment of the gear hub.
install a new bearing in the gear. Examine the outside
diameter of the idler gear hub and thrust washers; if
5. Lubricate the idler gear hub and idler gear bearings
scored or worn excessively, replace them.
liberally with clean engine oil.
6. Position the crankshaft gear and the camshaft gear
An idler gear bearing with two oil grooves has been
or balance shaft gear so that their timing marks will
incorporated in the idler gear and bearing assemblies
3D-
align with those on the idler gear. Refer to Figs. I and
beginning with engine serial number
2 in Section 1.7.1.
6773.
7. With these timing marks in alignment, install the
When a new bearing is installed in the idler gear, it
idler gear as shown in Fig. 2.
must not protrude beyond the gear face on-either side.
8. Apply a thin film of cup grease to the inner face
(face with the oil grooves) of the outer idler gear
Install Idler Gear and Bearing Assembly
thrust washer. Then place the thrust washer over the
end of the idler gear hub with the oil grooves in the
1. Place the inner thrust washer on the forward end of
side of the thrust washer facing the idler gear and the
the idler gear hub with the flat in the inner diameter
flat in the inner diameter of the thrust washer over the
of the thrust washer over the flat on the end of the
flat on the end of the idler gear hub.
ear hub and with the oil grooves in the thrust washer
facing the idler gear.
9. Check the backlash between the mating gears. The
backlash should be ,003" to .005" between new gears
and should not exceed ,007" between used gears.
2. Place the small protruding end of the idler gear hub
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