Jeep 2009 Grand Cherokee - Owner Manual - Manual (Page 287)

Engine Idling - In Cold Weather
Avoid prolonged idling in ambient temperatures below
0°F (-18°C). Long periods of idling may be harmful to
your engine because combustion chamber temperatures
can drop so low that the fuel may not burn completely.
Incomplete combustion allows carbon and varnish to
form on piston rings and injector nozzles. Also, the
unburned fuel can enter the crankcase, diluting the oil
and causing rapid wear to the engine.
Stopping The Engine
Before turning off your turbo diesel engine, always allow
the engine to return to normal idle speed and run for
several seconds. This assures proper lubrication of the
turbocharger. This is particularly necessary after any
period of hard driving.
Idle the engine a few minutes before routine shutdown.
After full load operation, idle the engine three to five
minutes before shutting it down. This idle period will
allow the lubricating oil and coolant to carry excess heat
away from the combustion chamber, bearings, internal
components, and turbocharger. This is especially impor-
tant for turbocharged, charge air cooled engines.
ENGINE BLOCK HEATER — IF EQUIPPED
The engine block heater warms the engine, and permits
quicker starts in cold weather. Connect the heater cord to
a ground-fault interrupter protected 110-115 Volt AC
electrical outlet with a grounded, three-wire extension
cord.
Use the heater when temperatures below 0°F (-18°C) are
expected to last for several days.
The block heater must be plugged in at least one hour to
have an adequate warming effect on the coolant.
The engine block heater cord is located:
• 3.7L/4.7L Engine — coiled and strapped to the engine
oil dipstick tube.
STARTING AND OPERATING 285
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