Check Fuel System For Leaks
Check Fuel System For Leaks
Tools
Technical values
Preliminary work
If only the high-pressure pump is removed and installed, the intake manifold must be removed for leak testing.
1. Battery disconnected.
2. Resonance tube removed.
3. Intake-air distributor removed.
Leak test
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
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:
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.
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 vapours.
- 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.
2. Fit pressure reducer onto gas bottle and connect to connecting line of air-spring strut filling unit VAS 6231 WE 1282.
2.1. Check threaded connections on pressure reducer are seated securely.
2.2. Check air adapter is seated securely.
2.3. Position tester -1- on the vehicle.
3. Screw gas bottle onto screw plug 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 litres of test gas -arrow-).
5. Open the rapid-action coupling on the fuel line (low-pressure connection) -1-.
WARNING:
Leaking fuel supply lines
- Emerging fuel
- Risk of fire
- Perform leak test.
6. Connect adapter hose -1- to rapid-action coupling of low-pressure line.
6.1. Connect air connection of filling unit -1- to adapter.
7. Apply the prescribed pressure to the closed fuel system.
7.1. There must be no pressure drop at the test gauge. - Pressure: 8 bar ± 1 bar
8. If the pressure at the test pressure gauge drops, coat connections with commercially available leak-locating spray (see recommendation).
8.1. Leaks are identifiable from bubbling and can also be heard as a hissing sound.
9. Leaks could be caused by a damaged sealing cone, loose connections or incorrectly fitted union nuts (damaged thread), for example.
9.1. Determine causes and correct immediately.
10. Remove test tools.
10.1. Test gases evaporate after a short time.
Subsequent work
If work is only carried out on the high-pressure pump, subsequent work phases 1 and 2 are no longer applicable.
1. Install intake-air distributor.
2. Install resonance tube.
3. Use PIWIS Tester 9718 to bleed the high-pressure system using the First start function.
4. Perform a test drive. A high-pressure adaptation is only necessary if the high-pressure pump has been replaced.