Fuel Delivery and Air Induction: Testing and Inspection
WM 200101 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.
-> 247419 Removing and installing resonance tube Service and Repair.
3. Intake-air distributor removed.
-> 244619 Removing and installing intake-air distributor 244619 Removing and installing intake-air distributor.
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
- Always perform a leak test 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.
- Blow residual fuel out of the lines and high-pressure pump (into a fuel-resistant container or cloth) using compressed air before installation.
- The tightening specifications must be strictly observed.
Overview of fuel system in engine compartment
Overview fuel system DFI
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:
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.
Example of warning sign
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.
Tester 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- ).
Adjusting pressure reducer settings
5. Open the rapid-action coupling on the fuel line (low-pressure connection) -1-.
Fuel lines
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.
Connection of test adapter to connection point fuel line
6.1. Connect air connection of filling unit -1- to adapter.
Connection of filling unit to test 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.
-> 244619 Removing and installing intake-air distributor 244619 Removing and installing intake-air distributor.
2. Install resonance tube.
-> 247419 Removing and installing resonance tube Service and Repair.
3. Use PIWIS Tester 9718 to bleed the high-pressure system using the First start function.
-> 2001IN Bleed fuel system (First start function) 2001IN Bleed fuel system (First start function)..
4. Perform a test drive. A high-pressure adaptation is only necessary if the high-pressure pump has been replaced.
-> 247019 Removing and installing DME (DFI) control unit Service and Repair.