How to Change the Antifreeze on a 5.9 Cummins

by Mark Robinson
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Heavy duty versions of the Dodge Ram pick-up come equipped with the 5.9 Cummins diesel engine, and this engine relies on a supply of antifreeze to function properly. Antifreeze not only helps keep the 5.9 Cummins engine cool, but it also provides it with protection against freezing in cold temperatures. Keeping a full, clean supply of antifreeze in the cooling system is important for maintaining the performance of the 5.9 Cummins engine.

Step 1

Park the vehicle on a flat, level surface and start the engine. Set the heater control temperature to its maximum level. Turn the engine off afterwards and allow it to cool down before attempting to drain the radiator.

Step 2

Locate the radiator drain plug and position a catch pan underneath it. Open the radiator drain plug with a pair of pliers and allow the coolant to drain from the reserve coolant tank. When the reserve tank is empty, open the radiator cap to allow the rest of the coolant to drain out of the radiator. Close the drain plug when the radiator is empty.

Step 3

Refill the radiator with a 50/50 mixture of water and antifreeze. You can also use pre-mixed antifreeze. When the radiator is full, refill the reserve tank with antifreeze until the level reaches the full mark.

Step 4

Move the catch pan out of the way. Start the engine and allow it to run until the upper radiator hose becomes warm to the touch. Check the level in the reserve tank and add antifreeze as necessary. The level should be between the ADD and FULL marks.

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