Fuel Delivery and Air Induction: Testing and Inspection

Checking Fuel System (High-Pressure Side) For Leaks

Tools







Technical values







INFORMATION:

Requirements
If only the high-pressure pump is removed and installed, the intake manifold must be removed for leak testing.
1. Battery disconnected.
2. Air cleaner housing removed.
3. Resonance tube removed.
4. Intake-air distributor removed.

Checking

Component overview

CAUTION:
Dirt on injection system components (intake manifold injection and direct fuel injection system)
- Material damage
- Rough-running engine
- Bad exhaust emissions

- Thoroughly clean connection points and adjacent areas before loosening them. If the engine is very dirty, wash it before starting disassembly work.
- Lay removed parts on a clean surface and cover them. Only use a clean, lint-free cloth.
- Carefully cover components or seal them if repair work will not be carried out immediately. Place rubber caps on connections. Seal intake openings with film or adhesive tape.
- Only install clean parts. Do not take spare parts out of the packaging until just before installation.
- Never use compressed air when the system is open. Do not move the vehicle.


INFORMATION:
- A leak test must always be performed in the high-pressure area after opening the fuel system.
- This is particularly important if components are disassembled and replaced.
- The threaded connections of the fuel lines must be coated with OKS 1700 lubricant (Part no. 000.043.207.36) before being screwed back on again.
- The tightening specifications must be strictly observed.
- Blow residual fuel out of the lines and high-pressure pump (into a fuel-resistant container or cloth) using compressed air before installation.

Overview of fuel system in engine compartment







Leak test on high-pressure side

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.

Tools:







CAUTION:
Incorrect test results will be obtained by unapproved test gases.
- Risk of leaks if the WRONG TEST MEDIA (air, petrol, water, etc.) are used.

- Only the approved test media guarantee comparability with fuels at pressures of up to 10 bar.

- The leak test media, which are used for technical purposes, are supplied as compressed gas in compressed gas bottles.

Materials:
Approved test media







WARNING:
Highly inflammable or explosive materials
- Danger of fire or explosion

- Avoid contact with hot parts or sources of ignition.
- Use suction to remove ignitable vapors.
- Attach warning sign in a clearly visible position.







1. Attach warning sign in a clearly visible position on the vehicle or position in the immediate working area.

WARNING:
Leaking fuel supply lines
- Emerging fuel
- Risk of fire

- Perform leak test.

2. Connect adapter hose to rapid-action coupling of low-pressure line -arrow-.







2.1. Connect air connection of filling unit -2- to adapter -1-.

3. Fit pressure reducer -2- onto gas bottle and connect to connecting line of filling unit -3-.
3.1. Check threaded connections on pressure reducer are seated securely.
3.2. Check air adapter is seated securely -4-.







3.3. Screw gas bottle onto screw plug -1- anticlockwise by 2-3 turns.

CAUTION:
Test pressure is exceeded
- Risk of damage to high-pressure pump

- The test gas test pressure must not exceed a maximum pressure of 10 bar.
- The setting is made at the pressure reducer.







4. Set the test pressure on the pressure reducer to between 7 and 9 bar (corresponds to a flow volume of approx. 26 - 28 liters of test gas -arrow-).







5. Using the test gauge -1- apply the ideal pressure to the closed fuel system.

- Pressure: 8 bar±1 bar
6. Coat connections with commercially available leak-locating spray (see recommendation).
6.1. Leaks are identifiable from bubbling and can also be heard as a hissing sound.
6.2. There must be no pressure drop at the test gauge.

7. Leaks could be caused by a damaged sealing cone, loose connections or incorrectly fitted union nuts (damaged thread), for example.
7.1. Determine causes and correct immediately.

8. Remove test tools.
8.1. The test gases evaporate after a short time.

Subsequent work
1. Install intake-air distributor.
2. Install resonance tube.
3. Install air cleaner housing.
4. Use PIWIS Tester 9718 to bleed the high-pressure system using the First Start function.
5. Perform a test drive. A high-pressure adaptation is only necessary if the high-pressure pump has been replaced.