Section 05: COOLING SYSTEM
PA1553
12
To replace a filter:
1. Close the two filter shutoff cocks on the filter
mounting head and unscrew the old filter
from mounting.
WARNING
Failure to relieve cooling system pressure
may result in personal injury.
2. Remove and discard the filter.
FIGURE 11: COOLANT FILTER 05089
3. Clean the filter adapter with a clean, lint-free
cloth.
4. Coat surface of gasket with oil, tighten 2/3 to
1 turn after gasket makes contact with head.
5. Open the two filter shutoff cocks.
6. Start engine and check for leaks.
CAUTION
Do not exceed recommended service
intervals.
9. RADIATOR
The radiator is mounted on the L.H. side of
engine compartment. It is designed to reduce
the temperature of the coolant under all
operating conditions. It is essential that the
radiator core be kept clean and free from
corrosion and scale at all times.
9.1 MAINTENANCE
Inspect the exterior of the radiator core every
25,000 miles (40 000 km) or once a year,
whichever comes first. Clean with a quality
grease solvent, such as a mineral spirits and dry
with compressed air. Do not use fuel oil,
kerosene, gasoline, or any caustic material. It
may be necessary to clean the radiator more
frequently if the vehicle is operated in extremely
dusty or dirty areas. Refer to coolant system
flushing and reverse flushing in this section for
maintenance of radiator interior.
10. VARIABLE SPEED RADIATOR FAN
The radiator fan has two thermostatically
controlled speeds. The ECM controls the speed
by comparing data from engine coolant
temperature, charge air cooling temperature,
engine oil temperature, A/C condenser
temperature, transmission retarder state,
manual switch to a set of calibration data. Once
fan switches to a state, it stays at that state for
30 seconds long before changing, to reduce
clutch cycling. The fan drive clutch is
electromagnetic; the ECM sends an electric
current to regulate speed by activating one
magnetic coil for the first speed and two
magnetic coils for the second speed.
The settings are:
o 190°F (87.5°C) Thermostat starts to open
o 192°F (89°C) Fan medium speed,
descending, off
o 196°F (91°C) Fan medium speed, rising, on
o 199.5°F (93°C) Fan high speed,
descending, off
o 203°F (95°C) Fan high speed, rising, on
o 205°F (96°C) Thermostats fully open
NOTE
In case of an electrical power failure: remove
the bolt from the end of the shaft and screw it
into the locking plate. This procedure will
prevent engine from overheating by forcing
fan rotation (Fig. 12).
On certain models, the mechanical locking
device consists of two threaded bushings
fixed on the pulley and two drilled metal plates
fixed on the rotor. Use the two screws located
on the face of the clutch to fasten the metal
plates and the bushings (Fig.13).
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