Ford F-650 Owner's Manual page 196

Engine-driven Cooling Fan (Fan
Clutch)
Your vehicle is equipped with an engine
driven cooling fan drive (also called a fan
clutch). This fan drive changes the fan
speed to match the vehicle's changing
cooling air flow requirements. Fan speed,
fan noise level and fuel consumption all
will increase based on the driving
conditions that include trailer towing, hill
climbing, heavy loads, high speed and high
ambient temperature, individually or in
combination.
The fan drive is designed to provide the
minimum fan speed (and resulting
minimum fan noise and fuel consumption)
required to meet the ever changing vehicle
cooling air flow requirements. You will hear
the amount of fan noise increasing and
decreasing as the engine power
requirements and vehicle driving conditions
change as you drive. This is to be expected
as being normal to the operation of your
vehicle. High levels of fan noise might also
be heard when your engine is first started,
and should normally decrease after driving
for a short time.
What You Should Know About Fail-
Safe Cooling
If the engine coolant supply is depleted,
this feature allows the vehicle to be driven
temporarily before incremental component
damage is incurred. The "fail-safe"
distance depends on ambient
temperatures, vehicle load and terrain.
How Fail-Safe Cooling Works
If the engine begins to overheat, the engine
coolant temperature gauge will move to
the red (hot) area and:
The coolant temperature
warning light will illuminate.
F650750 (TBC), enUSA, First Printing
Maintenance
over-temperature condition, the engine
will automatically switch to alternating
cylinder operation. Each disabled cylinder
acts as an air pump and cools the engine.
When this occurs the vehicle will still
operate. However:
• The engine power will be limited.
• The air conditioning system will be
disabled.
Continued operation will increase the
engine temperature and the engine will
completely shut down, causing steering
and braking effort to increase.
Once the engine temperature cools, the
engine can be re-started. Take your vehicle
to an authorized dealer as soon as possible
to minimize engine damage.
When Fail-Safe Mode Is Activated
Fail-safe mode is for use during
emergencies only. Operate your
vehicle in fail-safe mode only as long
as necessary to bring your vehicle to rest
in a safe location and seek immediate
repairs. When in fail-safe mode, your
vehicle will have limited power, will not be
able to maintain high-speed operation, and
may completely shut down without
warning, potentially losing engine power,
power steering assist, and power brake
assist, which may increase the possibility
of a crash resulting in serious injury.
Never remove the coolant reservoir
cap while the engine is running or hot.
193
I n f o r ma t i o n P r o v i d e d b y :
The service engine soon
indicator will illuminate.
If the engine reaches a preset
WARNINGS