Section 05: COOLING SYSTEM
PA1553
13
FIGURE 12: MECHANICAL LOCKING DEVICE 05061
FIGURE 13: SCREWS LOCATION
10.1 MAINTENANCE
1. Clean the fan and related parts with clean
fuel oil and dry them with compressed air. Do
not clean with steam or high-pressure jet.
2. Check the fan blades for cracks or other
damage. Replace the fan if the blades are
cracked or deformed.
3. Remove any rust or rough spots in the
grooves of the fan pulley. If the grooves are
damaged or severely worn, replace the
pulley.
4. Do not add any fluids or lubricants to the fan
driving mechanism.
5. Do not restrict fan rotation during engine
operation for any reason.
6. Do not operate fan-driving mechanism with a
damaged fan assembly. Replace a damaged
fan as soon as the fault is noted.
7. Immediately investigate and correct any
operator complaint involving driving
mechanism or cooling system performance.
8. When questions arise, obtain answers before
proceeding. Assistance is available through
the authorized Field Sales distributor serving
your area.
10.2 INSPECTION
DANGER
Set the starter selector switch in engine
compartment to the "Off" position to prevent
accidental starting of the engine.
o Check security of fasteners securing fan
blade assembly to fan driving mechanism.
o Check coupling installation between fan
blade assembly and gearbox.
o Visually inspect fan driving mechanism, fan
blade assembly, shroud, radiator, and
surrounding area for evidence of contact
between rotating and non-rotating parts.
o Check fan transfer belt for fraying, cracking,
and proper tension.
o Turn fan through at least 360° of rotation. It
should turn smoothly with no resistance.
10.3 THERMOSTAT OPERATION
Coolant temperature is controlled by two
blocking-type thermostats located in a housing
attached to the cylinder head, on the turbo side
of the engine (Fig. 14).
At coolant temperature below approximately
190°F (88°C), the thermostat valves remain
closed and block the flow of coolant from the
engine to the radiator. During this period, all of
the coolant in the system is recirculated through
the engine and directed back to the suction side
of the water pump via a bypass tube. As the
coolant temperature rises above 190°F (88°C)
the thermostat valves start to open, restricting
the bypass system, and allowing a portion of the
coolant to be recirculated through the radiator.
When the coolant temperature reaches
approximately 205-207°F (96-97°C) thermostat
valves are fully open, the bypass system is
blocked off and the coolant is directed through
the radiator.
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