981455 | 2010-2017 Freightliner M2 Cummins ISB HT650 Fan Clutch

Fit In Five Steps

How to replace a Freightliner M2 Cummins ISB HT650 Fan Clutch?

1.Materials Needed for Repair & Checking Problems

• Pulley locking tool
• Wrench
• Socket set with ratchet
• Rubber mallet

A fan clutch in good working order will have a fair amount of resistance when spun freehandedly. A good rule of thumb on the degree to which it slips is that if it spins more than 1 to 1-½ times on its own, it is safe to assume it needs to be replaced. Conversely, if it offers too much resistance in that it does not turn much beyond your assistance, it is safe to say it has seized up, which will also require replacement. A common technique used to measure appropriate fan speed is by using a timing light. Mark one of the fan blades with a white pen or chalk and use a timing light to check for changes in fan speed which may indicate problems as well. Other indicators of potential worn fan clutches may also be wobbling or bearing noises coming from the water pump shaft.

2.Remove the Fan Shroud & Cooling Fan

Because every application is different, some of these steps may need to be altered in order to fit your specific application. On most applications, however, the fan shroud is fastened by several bolts which will need to be removed in order to remove the shroud. Most applications will also require removal of the top radiator hose in order to get the fan shroud out. If this is the case, be sure to drain your coolant system prior to doing this. Once this is done, you can remove the fan shroud from the engine compartment. There are typically two types of ways the fan will be attached; one will be with four large bolts, in which case you will need just a basic wrench of the appropriate size to remove. The other method of attachment is a large nut that will likely require the use of a special pulley locking tool that is used to keep the pulley from moving while removing the nut. Since this is a specialty tool, most “do it yourself” may not have access to this tool. If this is the case, an alternative to using this specialty tool can be the use of a screwdriver. Use the screwdriver to hold keep the bolt in place while loosening the nut. Pay special attention to the placement of the screwdriver while doing this as this can damage the edges of the bolts if not done properly.

3.Rock from Side to Side & Remove the Bolts

Once all bolts and/or nuts have been removed, hold the fan with both hands slightly rocking it from side to side sliding it off of the water pump shaft. Secure the fan on a work table with plenty of room to work with the fan shaft facing your direction. There are four large bolts in the center of the fan assembly that hold the clutch in place. Remove these bolts and the clutch will be free from the fan.

4.Install the New Fan Clutch

Hold the new fan clutch in place aligning the bolt holes in the same place as the old clutch. Lightly run the bolts into the holes making sure the threads are lining up properly. Once you’ve run all bolts in finger tight, use your wrench to tighten them according to factory specifications (refer to your service manual or instructions with the new fan clutch).

5.Put the Fan Back into the Engine

Slide the fan assembly back into the engine compartment paying special attention to the water pump shaft alignment. Once in place, gently run the four bolts back into place holding the fan with one hand and running the bolts back in with the other. This may take some maneuvering to keep things straight, but remember, slow and steady and paying attention to detail is important. When all four bolts are back in place and run in finger tight, use the same wrench you used to remove them with to tighten them back up according to factory specifications (Again, refer to your service manual for exact specifications). If your application requires you to remove the top radiator hose to get the fan shroud out, now would be the time to reinstall that same radiator hose. Be sure to also remember to refill your coolant system if draining it was part of the removal process. Slide the fan shroud back into place lining up the bolt holes in the same position as it was removed. Run each bolt back in finger tight until all are accounted for and tighten per factory specifications (Refer to service manual for torque specs).