Checking Fuel System For Leaks

→ Ventilate the work area well.

→ Never ingest or inhale.

→ Read specific information on the Hazard Sheet.

→ Do not smoke, eat or drink in the work area.

→ Avoid contact with hot parts or sources of ignition.

→ Use suction to remove ignitable vapors.

→ Attach warning sign in a clearly visible position.

→ Perform leak test.

1. Place a cloth under the fuel supply line (low-pressure) and open the cap screw -1-  using two open-ended wrenches.
   Fig 1: Identifying Fuel Supply Line (Low-Pressure)

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   Information 

   • Check that the tool fittings are clean before starting the leak test  .
   • Blow out the tool fittings before assembly using gentle bursts of pressure to prevent dust and foreign bodies from getting into the high-pressure system during the leak test  .
   • Ensure that the tools for the leak test remain clean and free of dirt when stored  .
2. Adapter 9759 → Adapter 9759 with sealing ring  must be screwed hand-tight and fully sealed onto the fuel low-pressure line.
   Fig 2: Identifying Adapter 9759 With Sealing Ring

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   Fig 3: Identifying Fuel Low-Pressure Line Adapter 9759

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   NOTE: Test pressure is exceeded

   • Risk of damage to high-pressure pump

   → The test gas test pressure must be set to less than → Pressure: 10 bar  on the pressure reducer on the test gas bottle.

   WARNING: Working with compressed air

   • Risk of eye injuries
   • Risk of damaging and dirtying components

   → Wear protective goggles with side eye protection.

   → Protect the point at which the compressed air emerges with suitable material.

   → Place the point at which the compressed air emerges on suitable surfaces.

   Information 

   The use of unapproved test gases results in incorrect test results. Only approved test gases guarantee comparability with fuel high-pressure systems at pressures of up to 10 bar  .

3. Fit test gas bottle with pressure reducer and air-spring strut filling unit VAS 6231 WE 1282  securely so that no gas can escape → Test equipment setup  . Set pressure reducer to max. 10 bar pressure → Adjusting pressure reducer to between 7 and 9 bar of test gas pressure  .
   Fig 4: Identifying Filling Unit VAS 6231

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   Fig 5: Identifying Test Equipment Setup

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   Fig 6: Adjusting Pressure Reducer

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4. Air-spring strut filling unit VAS 6231 WE 1282  must then be connected to the Adapter 9759  (-1-  ). Tighten the connection if necessary.
   Fig 7: Connecting Adapter

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5. Depending on the high-pressure connections that were loosened (removed fuel distributor pipe or removed high-pressure pump), complete the following steps →

   If the fuel distributor pipe (high-pressure rail) was removed →

6. Before screwing the fuel distributor pipe (high-pressure rail) to the engine, quickly blow out residual fuel from the high-pressure pump and high-pressure line (intake) to the high-pressure rail.
   1. 6.1. Apply a quick burst of pressure using the filling unit and blow the residual fuel through the line into a cloth or receptacle. → Blowing out high-pressure line 
      Fig 8: Applying Quick Burst Of Pressure

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   2. 6.2. Drain residual fuel from the high-pressure distributor pipe before fitting it. Shake the high-pressure distributor pipe over a cloth to do this.
7. Fit high-pressure distributor pipe (high-pressure rail) and tighten it to the correct tightening torques. → Installing fuel distributor pipe (fuel rail) - section on "Installing"
   NOTE: Test pressure is exceeded

   • Risk of damage to high-pressure pump

   → The test gas test pressure must be set to less than → Pressure: 10 bar  on the pressure reducer on the test gas bottle.

8. Use air-spring strut filling device VAS 6231 WE 1282  to apply test gas pressure of between 7 and just under 10 bar to the completely fitted high-pressure system -2-  . The pressure is distributed slowly in the system and can increase slightly on the pressure gauge. If there is a constant drop in pressure, there is a leak in the system.
   Fig 9: Applying Pressure

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9. Spray all connection points in the high-pressure system with commercially available leak-locating spray. If the pressure drops even though the threaded joints are perfectly sealed, also spray the soldered joints and connecting pipes as well as the high-pressure pump and test equipment with leak-locating spray.
10. If there is a leak, Gently Sashaying  , Moving And Growing  air bubbles → Leaks  will emerge. These could be caused by a damaged seal, loose connections or incorrectly fitted union nuts, for example. The cause must be determined and corrected.
    Fig 10: Locating Fuel System Leaks

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    If the high-pressure pump was removed →

11. Before screwing the high-pressure line (intake) to the high-pressure pump, residual fuel must be blown out of the high-pressure pump.
    1. 11.1. Apply a quick burst of pressure using the filling unit and blow the residual fuel through the connection piece into a cloth.

       → Blowing out high-pressure pump 

       Fig 11: Applying Quick Burst Of Pressure

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12. Screw high-pressure line correctly to the high-pressure pump. → Installing high-pressure pump - section on "Installing"
    NOTE: Test pressure is exceeded

    • Risk of damage to high-pressure pump

    → The test gas test pressure must be set to less than → Pressure: 10 bar  on the pressure reducer on the test gas bottle.

13. Use air-spring strut filling device VAS 6231 WE 1282  to apply test gas pressure of between 7 and just under 10 bar to the fitted high-pressure pump. The pressure is distributed slowly in the system and can increase slightly on the pressure gauge. If there is a constant drop in pressure, there is a leak in the system.
    Fig 12: Applying Test Gas Pressure

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14. Spray all connection points for the high-pressure pump with commercially available leak-locating spray. If the pressure drops even though the threaded joints are perfectly sealed, also spray other connection points as well as the high-pressure pump and test equipment with leak-locating spray.
15. If there is a leak, Gently Sashaying  , Moving And Growing  air bubbles will emerge (union nut on injector is shown) → Leaks  . These could be caused by a damaged seal, loose connections or incorrectly fitted union nuts, for example. The cause must be determined and corrected.
    Fig 13: Locating Fuel System Leaks

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