Fuel Rail: Testing and Inspection
WM 243001 Checking fuel distribution pipe for leaks
Tools
Technical values
Preliminary work
WARNING
Toxic substances
- Danger of poisoning or suffocation
-> Ventilate the work area well.
-> Never ingest or inhale.
-> Read specific information on the Hazard Sheet.
-> Wear personal protective gear.
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.
NOTICE
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. Do not use fibre-shedding cloths.
-> 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.
WARNING
Leaking fuel supply lines
- Emerging fuel
- Risk of fire
-> Perform leak test.
Information
Do not bend high-pressure lines. Always remove the high-pressure distribution pipe and other fuel-supply components in the high-pressure area completely. Check that the connection points are not damaged and are perfectly clean and make sure there is no thread damage. Fit union nuts on all connection points by hand before screwing in screws or bolts. Remove dirt on the conical/ball joints. Check connection points for leaks following fitting.
Information
- The ignition must be switched off when working on the fuel system.
- Absorb any escaping fuel using a suitable binding material or a cloth.
- Cloths which have absorbed fuel must be disposed of according to the applicable national laws.
- The fuel system must be depressurised before starting work on it.
- Only work on the fuel system in well-ventilated rooms.
- Any seals which have been removed must always be replaced.
- After disassembly work on the high-pressure injection system, fit the components to the prescribed torques.
- Visible threaded joints must be inspected for leaks with the engine idling after a test drive.
- For the check to be performed correctly, the components to be checked must not contain any fuel. When dismantling, remove fuel from the lines.
1. Pull out fuses for fuel pumps in the central electrical system or disconnect battery. This ensures that the fuel pumps do not start up when the door is opened.
Information
Component overview
High-pressure components =>
Fuel injectors
Fuel distributor pipe
High-pressure pump, turbo engine
High-pressure pump, naturally aspirated engine
Tools and materials
Special tools
Tools for leak test
Approved leak-locating gases (test media)
Checking fuel high-pressure system for leaks
WARNING
Toxic substances
- Danger of poisoning or suffocation
-> Ventilate the work area well.
-> Never ingest or inhale.
-> Read specific information on the Hazard Sheet.
-> Wear personal protective gear.
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.
WARNING
Leaking fuel supply lines
- Emerging fuel
- Risk of fire
-> Perform leak test.
1. Place a cloth under the fuel supply line (low-pressure) and open the line using two open-ended wrenches. Counter at the centre piece while doing this and loosen the union nut at the engine side. => Fuel low-pressure line
Junction point for lines in engine compartment
Fuel low-pressure line
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. Screw adapter 1318/7 => Adapter 1318/7 from K-Jetronic Tester V.A.G. 1318 WE 1291 hand-tight onto the fuel low-pressure line => Adapter on low-pressure line.
Adapter 1318/7
Adapter on low-pressure line
NOTICE
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.
Filling unit VAS 6231
Test equipment setup
Adjusting pressure reducer to between 7 and 9 bar of test-gas pressure
4. Air-spring strut filling unit VAS 6231 WE 1282 -2- must then be connected to the adapter. Tighten the connection if necessary.
Filling unit on adapter
5. Depending on the high-pressure connections that were loosened (removed fuel distribution pipe or removed high-pressure pump), complete the following steps =>
6. If the fuel distribution pipe (high-pressure rail) was removed =>
6.1. Before screwing the fuel distribution 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.
6.2. 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
Blowing out high-pressure line
6.3. Drain residual fuel from the high-pressure distribution pipe before fitting it. Shake the high-pressure pipe over a cloth to do this.
6.4. Fit high-pressure distribution pipe (high-pressure rail) and tighten it to the correct tightening torques. -> 243019 Removing and installing fuel distribution pipe Service and Repair
NOTICE
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.
6.5. 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. 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.
6.6. 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.
6.7. If there is a leak, gently sashaying, moving and growing air bubbles => Leak 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.
Leak
7. If the high-pressure pump was removed =>
7.1. Before screwing the high-pressure line (intake) to the high-pressure pump, residual fuel must be blown out of the high-pressure pump.
7.2. 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
Blowing out high-pressure pump
7.3. Screw high-pressure line correctly to the high-pressure pump. -> 246319 Removing and installing high-pressure pump Service and Repair
NOTICE
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.
7.4. 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.
7.5. 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.
7.6. If there is a leak, gently sashaying, moving and growing air bubbles will emerge (union nut on injector is shown). These could be caused by a damaged seal, loose connections or incorrectly fitted union nuts, for example. The cause must be determined and corrected.
Leak
Subsequent work
1. Remove tool setup.
2. Fit the fuel line => Junction point for lines in engine compartment => Fuel low-pressure line. To do this, fit the fuel supply line (low pressure) correctly at the marking. Counter at the centre piece.=> Tightening torque: 30 Nm (22 ftlb.)
Junction point for lines in engine compartment
Fuel low-pressure line
3. Fit fuses or connect battery.
4. Bleed the fuel high-pressure system.