Replacing the Ford F-250 diesel engine coolant constitutes no different a process from changing the coolant in the F-250 gas-powered Ford truck. According to the Autos website, completing routine coolant changes every other year or every 30,000 miles helps reduce sludge buildup and chemical breakdown of your fluid. If you use your F-250 for heavy hauling and towing, or you live in a climate with extremely hot or very cold temperatures, change your coolant at shorter intervals.
Open the radiator filler cap located on the overflow tank, directly behind the radiator.
Place a drainage pan large enough to drain 5 gallons of coolant directly below the drain valve on the bottom of the radiator.
Open the drainage valve by turning it counterclockwise with a pair of pliers. Allow all of the fluid to drain, then close the valve by turning it clockwise.
Drain 2.5 gallons of low-silicate radiator fluid into the filler spout of the overflow tank, then drain 2.5 gallons of distilled water into the filler spout of the radiator overflow tank.
Start the Diesel F-250 and run it for five minutes with the filler cap still open. This precaution purges the radiator and coolant system of air bubbles. Close the overflow tank cap after five minutes.
