Coolant refill capacity
To find out how much fluid your vehicle ’ s cooling system can hold, refer
to Refill capacities in this chapter.
Fill your engine coolant reservoir as outlined in Adding engine coolant
in this chapter.
Severe climates
If you drive in extremely cold climates (less than – 36 ° C[ – 34 ° F]):
• It may be necessary to increase the coolant concentration
above 50%.
• NEVER increase the coolant concentration above 60%.
• Increased engine coolant concentrations above 60% will
decrease the overheat protection characteristics of the engine
coolant and may cause engine damage.
• Refer to the chart on the coolant container to ensure the
coolant concentration in your vehicle will provide adequate
freeze protection at the temperatures in which you drive in the
winter months.
If you drive in extremely hot climates:
• It is still necessary to maintain the coolant concentration
above 40%.
• NEVER decrease the coolant concentration below 40%.
• Decreased engine coolant concentrations below 40% will
decrease the corrosion protection characteristics of the engine
coolant and may cause engine damage.
• Decreased engine coolant concentrations below 40% will
decrease the freeze protection characteristics of the engine
coolant and may cause engine damage.
• Refer to the chart on the coolant container to ensure the
coolant concentration in your vehicle will provide adequate
protection at the temperatures in which you drive.
Vehicles driven year-round in non-extreme climates should use a 50/50
mixture of engine coolant and distilled water for optimum cooling system
and engine protection.
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.
2004 Navigator (nav)
Owners Guide (post-2002-fmt)
USA English (fus) Maintenance and Specifications
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How fail-safe cooling works
If the engine begins to overheat:
• The engine coolant temperature
gauge will move to the red (hot)
area.
• The and 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:
• The engine will completely shut down.
• Steering and braking effort will 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.
When fail-safe mode is activated
You have limited engine power when in the fail-safe mode, so drive the
vehicle with caution. The vehicle will not be able to maintain high speed
operation and the engine will run rough. Remember that the engine is
capable of completely shutting down automatically to prevent engine
damage, therefore:
1. Pull off the road as soon as safely possible and turn off the engine.
2. Arrange for the vehicle to be taken to a service facility.
3. If this is not possible, wait a short period for the engine to cool.
4. Check the coolant level and replenish if low.
Never remove the coolant reservoir cap while the engine is
running or hot.
2004 Navigator (nav)
Owners Guide (post-2002-fmt)
USA English (fus)Maintenance and Specifications
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