Cooling System Flushing
Cooling System Flushing - Diesel Engine
NOTICE: This procedure should be used to clean and flush the diesel cooling system to make sure that all rust is removed from the system. Failure to follow these instructions may result in engine damage.
NOTICE: If oil or fuel is present in the cooling system, refer to the appropriate Technical Service Bulletins (TSBs) that pertain to 6.0L diesel engine cooling system concerns and follow the procedure outlined. Failure to remove all contaminants from the cooling system may result in engine damage.
1. WARNING: Always allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.
Once pressure is released, remove the pressure relief cap.
- Drain the cooling system. For additional information, refer to Cooling System Draining, Filling and Bleeding Cooling System Draining, Filling and Bleeding.
2. Remove the thermostat. For additional information, refer to Thermostat - 6.4L Diesel Service and Repair.
3. NOTE: Both thermostats must be removed from the housing assembly.
Position the thermostat housing assembly in the vise. Press down on the thermostat crossbar and rotate the thermostats to remove them from the housing assembly.
4. NOTE: Do not fill cooling system at this time.
NOTE: Use the old O-ring seal during the flushing procedure.
Install the thermostat housing assembly without the thermostats. For additional information, refer to Thermostat - 6.4L Diesel Service and Repair.
5. NOTE: The RH cylinder block drain plug is not removed at this time.
Remove the LH cylinder block drain plug and drain the cylinder block of coolant.
6. NOTE: Lightly lubricate the O-ring seal on the cylinder block drain plug with clean engine oil before installing.
Install the LH cylinder block drain plug.
- Tighten to 20 Nm (177 lb-in).
NOTE: For commercial vehicles with auxiliary heaters, use 2.83L (3 qt) of Motorcraft(R) Engine Cooling System Iron Cleaner (VC-9).
7. NOTE: The use of excessive Motorcraft(R) Engine Cooling System Iron cleaner (VC-9) can cause gelling.
Fill the cooling system with water and 1.89L (2 qts) of Motorcraft(R) Engine Cooling System Iron Cleaner (VC-9).
8. NOTE: Failure to allow the engine to run for one hour will result in insufficient cleaning of the cooling system.
Using the scan tool, use the active command and set the engine rpm to 2,000. Run the engine for one hour.
9. WARNING: Always allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.
Once pressure is released, remove the pressure relief cap.
- Drain the cooling system. For additional information, refer to Cooling System Draining, Filling and Bleeding Cooling System Draining, Filling and Bleeding.
- Leave the radiator draincock open.
10. Remove the LH cylinder block drain plug.
11. Remove the starter. For additional information, refer to Starting System.
12. Remove the RH cylinder block drain plug.
13. NOTE: Failure to flush all the Motorcraft(R) Engine Cooling System Iron Cleaner (VC-9) from the cooling system will result in shortened coolant protection against corrosion.
Flush the cooling system with clean water through the degas bottle to completely remove the Motorcraft(R) Engine Cooling System Iron Cleaner (VC-9) from the cooling system.
- Flush the cooling system with clean water until no foam or discoloration is draining from the cooling system.
14. Backflush the heater core. For additional information, refer to Heater Core Backflushing Heater Core Backflushing.
15. NOTE: Failure to flush all the Motorcraft(R) Engine Cooling System Iron Cleaner (VC-9) from the cooling system will result in shortened coolant protection against corrosion.
Flush the cooling system with clean water through the degas bottle to completely remove the Motorcraft(R) Engine Cooling System Iron Cleaner (VC-9) from the cooling system.
- Flush the cooling system with clean water until no foam or discoloration is draining from the cooling system.
16. Close the radiator draincock.
17. NOTE: Do not fill the cooling system at this time.
NOTE: Replace the thermostat housing assembly O-ring seal.
Install the thermostats. For additional information, refer to Thermostat - 6.4L Diesel Service and Repair.
18. NOTE: Lightly lubricate the O-ring seal on the cylinder block drain plug with clean engine oil before installing.
Install the RH cylinder block drain plug.
- Tighten to 20 Nm (177 lb-in).
19. Install the starter. For additional information, refer to Starting System.
20. NOTE: Lightly lubricate the O-ring seal on the cylinder block drain plug with clean engine oil before installing.
Install the LH cylinder block drain plug.
- Tighten to 20 Nm (177 lb-in).
21. Fill the cooling system. For additional information, refer to Cooling System Draining, Filling and Bleeding Cooling System Draining, Filling and Bleeding.