Before servicing the fan clutch, start by removing the battery negative cables and taking out the fan shroud bolts, placing the shroud beside the top of the engine while the fan pulley bolts stay where they are. Attached to the fan hub shaft is the thermal viscous fan drive/blade assembly; to remove it, turn the mounting nut clockwise as its threads turn Left-hand. A Snap-On 36 Mm Fan Wrench called Sp346, found in the Snap-On Cummins Diesel Tool Set 2017Dsp, is suitable and a bar or screwdriver should remain between the fan pulley bolts. Both the fan shroud and fan assembly should now be out, so remove all four bolts from the
Fan Blade/viscous fan drive mounting and check the fan for any cracks, loose rivets or bent blades. Some engines with serpentine belts use reverse rotating fans and viscous fan drives that have the word Reverse on the casing; switching the fan or drive to the opposite end can cause engine overheating. Gentle soap and water are the right cleaners to use when cleaning fan blades. After changing the fan assembly because of mechanical damage, check the
Water Pump and viscous fan drive for possible damage caused by shaking the assembly. With a flat screwdriver, push each bolt of the blade assembly out, then remove the fan; lay it with the leading edge down on a flat surface and if there is more than 2.0 mm (0.090 inch) clearance on either side or if any rocking motion is seen, replace the fan. Look over the fan assembly for any damage such as cracks, bends, loose rivets or broken welds; if there is any harm, change the part. During installation, fixed the fan blade assembly on the viscous fan drive, tightening the bolts to 23 Nm (17 ft. lbs.) torque. Place the fan shroud and the fan blade or viscous fan drive into one assembly, fit the viscous fan drive assembly onto the fan hub shaft and secure it with a mounting nut tightened to 57 Nm (42 ft. lbs.) torque. Tighten all the fan shroud bolts to 6 Nm (50 inch lbs.) torque and then hook up the negative cables on the battery once more. When the new viscous fan drive is installed, increase engine speed to 2000 rpm and hold for about two minutes to ensure the fluid is distributed inside it.