TM 5-3895-346-14
ENGINE OVERHAUL
ENGINE COOLING PAN
ENGINE COOLING FAN
The engine cooling fan is driven directly by the crankshaft (Fig. 1). Because of high vibration loads on certain
applications, a new 22-inch five balde-type fan with a thicker spider is now being used on the in-line 53 engines
as required. This is effective with engine serial number 4D-154007. The former and new fan assemblies are
interchangeable on an engine, but only the new fan assembly is serviced.
Effective with engine serial number 4D-68816 new fan hub assemblies are being used on the in-line engines.
The new assemblies are similar to the integral cast shaft and bracket design, with tapered roller bearings,
currently used on the V-type engines (Fig. 4). A new pulley hub assembly similar to the present hub assembly
is now being used on certain four cylinder Series 53 engines to extend operational life under severe dirt
conditions. It includes a front ball bearing and a rear roller bearing along with a hubcap (with relief valve), a
dust cap, and a grease fitting in the fan pulley hub (Fig. 7).
The belt-driven fan is bolted to a combination fan hub and pulley which turns on a sealed ball bearing assembly
(former in-line engines), two tapered roller bearings (present in-line engines) or a front ball bearing and a rear
roller bearing (new 4-53 engines). The crankshaft-driven fan is bolted to the crankshaft pulley.
LUBRICATION
The sealed ball bearing, used in the fan hub assembly shown in Fig. 2, is
Figure 1. Crankshaft-Driven Fan
Figure 2. Ball Bearing-Type Fan Hub
Mounting (In-Line Engine
Assembly
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