C7.1 Industrial Engine Caterpillar

Required Tools

Flushing Procedure

1. Turn the key switch to the OFF position for 2 minutes. The key switch must be OFF for 2 minutes to allow the Diesel Exhaust Fluid (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.

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	g03406433
   Typical example (1) DEF suction line (2) Manifold (DEF heater) (3) Harness assembly (4) Coolant supply to manifold (DEF heater) (5) DEF backflow line (6) Coolant supply to DEF pump

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	g06132482
   Typical example

5. Remove filter (7) from manifold (DEF heater) (2). Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install" for the correct procedure.

6. Remove filter (8) from manifold (DEF heater) (2). Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install" for the correct procedure.
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   Illustration 3	g06130964
   Typical example

7. Inspect the optical sensors (9) (if equipped) for visible debris. If visible debris is present, clean the optical sensors by wiping the sensors gently with a clean, soft cloth. If no visible debris is present on the optical sensors, then manifold (DEF heater) (2) assembly must be replaced.

   Note: The new manifold (DEF heater) with optical quality sensor is equipped on later engines.

8. Flush the DEF suction and backflow connections on the manifold (DEF heater) using distilled or deionized water. Install new filter (8) onto the manifold (DEF heater). Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install" for the correct procedure.

9. Install new filter (7) onto the manifold (DEF heater). Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install" for the correct procedure.
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   NOTICE
   Do not dry the inside of the DEF tank with any type of cloth or paper towel. Fibers left in the tank will obstruct the DEF filters.

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

11. 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 4	g06130968
    Typical example (10) Connector for DEF suction line containing in-line filter (11) DEF pump (12) DEF filter cap

12. Replace the connector at the DEF pump inlet port. The connector contains an in-line filter which can only be replaced by replacing the connector assembly. Refer to Disassembly and Assembly, "Diesel Exhaust Fluid (DEF) Pump - Remove and Install" for more information.

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

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

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

    Note: Use de-ionized water, distilled water, or Diesel Exhaust Fluid (DEF) to lubricate the O-ring seals of the connections of the diesel exhaust fluid lines before installation of the diesel exhaust fluid lines. If DEF has been used to lubricate the O-ring seals of the connections of the diesel exhaust fluid lines. The excess DEF must be cleaned from the connections of the diesel exhaust fluid lines.

16. Fill the DEF tank completely with new DEF. The new DEF must meet ISO 22241 standards.

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

18. Connect to the electronic service tool.

19. 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.