2009 Jeep Grand Cherokee Owner's Manual - Page 287

STARTING AND OPERATING 285 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 important 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. 5