DETROIT DIESEL 53
1.7.4
IDLER GEAR AND BEARING ASSEMBLY
The engine idler gear and bearing assembly, located at
The idler gear is positioned on the right-hand side for a
the flywheel end of the engine, meshes with the
right-hand rotating engine as viewed from the rear.
camshaft and crankshaft gears and rotates on a
Refer to Fig. 6. under General Description.
stationary hub. The hub is secured directly to the
cylinder block by a bolt which gasses through the hub
and three bolts which pass through the flywheel
housing, hub and end plate (Fig. 1.).
Remove Idler Gear and Bearing Assembly (Flywheel
Housing Removed)
Two timing marks (a triangle within a circle) are
stamped on the idler gear diametrically opposite (180)
1. Remove the idler gear outer thrust washer from the
to one another.
idler gear hub (Fig. 3.).
The inside diameter of the idler gear bearing is 2.186 "-
2. Slide the idler gear straight back off of the idler gear
2.187 " and the outside diameter of the idler gear hub is
hub.
2.1825 "-2.1835 ". Therefore, the clearance between
the idler gear hub and the idler gear bearing -is .0025 "
3. Remove the bolt which secures the idler gear hub to
to .0045 ", with a maximum allowable wear limit of .007
".
A thrust washer is provided on both sides of the idler
gear and bearing assembly. The standard thickness of
the idler gear and bearing assembly is 1.233 " to 1.234 "
and the standard thickness of the two thrust washers is
.236 " to .240 "; thus, the clearance between the thrust
washers and the idler gear is .006" to .013", with a
maximum allowable wear limit of .017".
Fig. 2. - Installing Idler Gear
Fig. 1. - Installing Idler Gear Hub
1972 General Motors Corp.
August, 1972
SEC. 1.7.4 Page 1
