C3.4B Engines for Caterpillar Built Machines Caterpillar

Required Tools

Flushing Procedure

1. Turn the key switch to the OFF position. The key switch must be OFF to allow the DEF pump to purge, ensuring the system is free of pressurized DEF.

   Note: Allow the full 2 minutes after turning the key switch to the OFF position before turning the battery disconnect switch to the OFF position. Refer to Operation and Maintenance Manual, "Battery Disconnect Switch" for more information.

2. Drain the existing DEF from the DEF tank.

   Note: All DEF drained or flushed during this procedure must be disposed of as per local regulations and mandates.

3. Drain the engine coolant to an appropriate level that will allow the coolant lines to be removed from the tank header. Refer to Operation and Maintenance Manual for more information.
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   Illustration 1	g03708638
   Typical example (1) DEF suction line (2) Manifold (DEF heater) (3) Harness assembly (4) DEF backflow line (5) Coolant return to the engine (6) Coolant supply to manifold (DEF heater)

4. Remove the manifold (DEF heater) from the DEF tank. Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install" for the correct procedure.
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   Illustration 2	g03710736
   Typical example (2) Manifold (DEF heater) (7) Filter

5. Remove the filter from the manifold (DEF heater). Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install" for the correct procedure.

6. Flush the DEF suction and backflow connections on the manifold (DEF heater) using distilled water. Install a new filter onto the manifold (DEF heater). Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install" for the correct procedure.

7. Position the suitable container under the DEF tank drain and flush the DEF tank thoroughly.

8. Reinstall the manifold (DEF heater) into the DEF tank. Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install" for the correct procedure.
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   Illustration 3	g03734661
   Typical example (8) DEF pump (9) DEF filter cap

9. Replace the Diesel Exhaust Fluid (DEF) filter. Refer to Operation and Maintenance Manual for the correct procedure.

10. Flush the DEF suction and backflow lines into a suitable container using distilled water. The minimum quantity of distilled water that is required is 7.57 L (2 US gal).

11. Reconnect all lines to the DEF pump and to the manifold (DEF heater). Refer to Disassembly and Assembly for the correct procedures.

12. Fill the DEF tank to the appropriate level with new DEF. Operation and Maintenance Manual for more information. The new DEF must meet ISO 22241 standards.

13. Start the engine. Refer to Operation and Maintenance Manual for the correct procedure.

14. Connect to the electronic service tool.

15. Perform the "Aftertreatment System Functional Test" in the electronic service tool. This test will verify that the DEF system is working correctly following the flush and filter replacement.