FORD 1999 F-550 v.1 - Manual (Page 187)

Severe winter climate
If you drive in extremely cold climates (less than –36°C [–34°F]), it may
be necessary to increase the coolant concentration above 50%. Refer to
the chart on the coolant container to ensure the coolant concentration in
your vehicle is such that the coolant will not freeze at the temperature
level in which you drive during winter months. Never increase the engine
coolant concentration above 60%. Leave a 50/50 mixture of engine
coolant and water in your vehicle year-round in non-extreme climates.
What you should know about fail-safe cooling (if equipped)
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.
• the
symbol will illuminate.
• the
symbol will illuminate.
• the Service Engine Soon
indicator light will illuminate.
If the engine reaches a preset 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 a service facility as soon as possible to minimize engine
damage.
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Maintenance and care
187