TM 5-3895-346-14
ENGINE OVERHAUL
ENGINE COOLING FAN
NOTE
The inner and outer races are only serviced as a rear roller bearing assembly.
When installing the rear bearing inner race, press it on the shaft and position it 1.35 to 1.37 inches from the end
of the shaft.
Check the fan blades for cracks. Replace the fan if the blades are badly bent, since straightening may weaken
the blades, particularly in the hub area.
Remove any rust or rough spots in the grooves of the fan pulley and crankshaft pulley. If the grooves are dam-
aged or severely worn, replace the pulleys.
New 0.500 inch thick and 0.800 inch thick fan hub spacers and a new fan hubcap replace the former spacer
and cap assemblies to provide spacers compatible with the six bolthole mounting fan hub assemblies. The
spacers (individually or in combination) also provide a means for setting the different clearances between the
back of the fan blades and front groove of the crank-shaft pulley.
The spacers have a flange on one side that serves as a pilot for the fan as well as a spacer pilot for the second
spacer when two or more spacers are used together.
EXAMPLE
A former 1.800-inch-thick spacer and cap assembly have been replaced by two 0.500-inch-thick spacers, one
0.800-inch-thick spacer, and the new fan hubcap.
When replacing the former fan hub spacer, be sure and include the new cap.
The fan hub assembly illustrated in Fig. 5 has been revised. The revisions consist of an increase in the bearing
inner race and shaft bearing radii, a hardened hub-retaining nut and washer, and the addition of spacers and
shims on the shaft between the bearings. This type fan hub assembly should be rebuilt with the current parts,
especially where the former undercut shaft is used. The current spacers and shims cannot be used with the
former shaft.
To replace the shaft, remove the groove pin and press the shaft from the adjusting bracket. Press the new
shaft in the bracket to the dimension shown in Fig. 5. Then drill the shaft, using the hole in the bracket as a
guide, and install a groove pin.
The spindle-type fan hub assembly illustrated in Fig. 6 has also been revised. A bearing spacer has been
added and a new outer bearing, which provides a closer fit on the shaft, replaces the old. A baffle has also
been added to retain the grease and assure lubrication at the outer bearing. To facilitate installation of the
grease baffle, a 0.030 inch by 15chamfer has been added to the bore in the pulley.
The tapped hole in the end of the shaft has been counterbored and increased in depth from 1.000 inch to 1.260
inches. A longer hub-retaining bolt and a 0.320-inch-thick washer replaces the former bolt and 1/8-inch-thick
washer.
New shims, assembled between the bearing spacer and the inner race of the outer bearing, provide .001 inch to
.006 inch end play. The former shims, which were assembled between the hub-retaining washer and the end of
the shaft, provide 0.002 inch to 0.004 inch end play.
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