243001 Checking Fuel Distribution Pipe (Fuel Rail) on DFI Engines For Leaks
WM 243001 Checking fuel distribution pipe (fuel rail) on DFI engines for leaks
Tools
Technical values
Preliminary work
DANGER
Danger of poisoning from fuels.
-> Gasoline is toxic.
-> Inhaling vapours can cause irritation of the mucous membranes and eyes.
-> It can be carcinogenic. It represents a serious risk to health when inhaled, touched or swallowed over longer periods.
-> Only work on the fuel system in well-ventilated rooms.
-> Wear protective gloves that are fuel-resistant.
-> Wear a breathing mask with active charcoal filter; do not breathe in any fuel vapours.
-> Ensure that there is adequate ventilation and extract all fuel vapours.
-> Before opening the fuel lines or fuel hoses, relieve the fuel pressure.
-> Collect escaping fuel, absorb it if necessary with a suitable binding material and dispose of properly.
-> Pay attention to cleanliness when working on the fuel system.
DANGER
Danger of fire from fuel.
-> Keep clear of ignition sources.
-> Do not smoke.
-> Disconnect battery.
-> Danger of fire due to naked flames and sparks, e.g. during welding or grinding work.
-> Danger of fire due to escaping fuel, e.g. on hot engine components or due to electrostatic charge. Allow engine to cool down.
-> Secure the vehicle, e.g. with a warning sign.
-> Change any clothing soaked with fuel immediately.
-> In case of fire, use CO2 or dry powder fire extinguishers.
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. 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.
CAUTION
Danger of fire from leaking high-pressure lines.
- Fuel can leak out if high-pressure lines are bent or damaged.
- Fuel can leak out if threaded joints are not fitted correctly.
- Fuel can leak out if the tightening specifications are not observed.
-> Never bend high-pressure lines.
-> The high-pressure distribution pipe (rail) or other fuel feed components in the high-pressure area must always be completely removed.
-> Perform a visual inspection to ensure that connection points are undamaged and perfectly clean.
-> Check that threaded joints at connection points are not seized up or corroded. Make sure the thread is not damaged.
-> Fit union nuts on all connection points by hand before screwing in screws or bolts.
-> Pay attention to cleanliness. Remove dirt on the ball/conical joints.
-> Check or inspect connection points for leaks following assembly.
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. Remove rear engine-compartment cover. => 700219 Removing and installing front trim (engine compartment) - section on "Removing"
2. 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
Fuel injectors
Fuel distribution pipe
High-pressure pump, turbo engine
High-pressure pump, naturally aspirated engine
Tools and materials
Tools and leak-locating media for the leak test
Tools for leak test
Approved leak-locating gases (test media)
Checking fuel distribution pipe (fuel rail) for leaks
DANGER
Danger of poisoning from fuels.
-> Gasoline is toxic.
-> Inhaling vapours can cause irritation of the mucous membranes and eyes.
-> It can be carcinogenic. It represents a serious risk to health when inhaled, touched or swallowed over longer periods.
-> Only work on the fuel system in well-ventilated rooms.
-> Wear protective gloves that are fuel-resistant.
-> Wear a breathing mask with active charcoal filter; do not breathe in any fuel vapours.
-> Ensure that there is adequate ventilation and extract all fuel vapours.
-> Before opening the fuel lines or fuel hoses, relieve the fuel pressure.
-> Collect escaping fuel, absorb it if necessary with a suitable binding material and dispose of properly.
-> Pay attention to cleanliness when working on the fuel system.
DANGER
Danger of fire from fuel.
-> Keep clear of ignition sources.
-> Do not smoke.
-> Disconnect battery.
-> Danger of fire due to naked flames and sparks, e.g. during welding or grinding work.
-> Danger of fire due to escaping fuel, e.g. on hot engine components or due to electrostatic charge. Allow engine to cool down.
-> Secure the vehicle, e.g. with a warning sign.
-> Change any clothing soaked with fuel immediately.
-> In case of fire, use CO2 or dry powder fire extinguishers.
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. -1 only-
Tank ventilation and 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. Adapter 9759 => Adapter 9759 with sealing ring must be screwed hand-tight and fully sealed onto the fuel low-pressure line. -arrow-
Adapter 9759 with sealing ring
Adapter 9759 on fuel low-pressure line
CAUTION
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.
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 gases as the test medium guarantee comparability with fuel high-pressure systems 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.
CAUTION
Increased risk of accident due to compressed gas bottles under high pressure (up to 200 bar).
- Injuries and material damage are possible.
-> Observe the relevant operating regulations for handling compressed air and gas filling units.
-> Observe accident prevention regulations.
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 must then be connected to the adapter 9759 ( -1- ). Tighten the connection if necessary.
Connecting adapter
5. Depending on the high-pressure connections that were loosened (removed fuel distribution pipe or removed high-pressure pump), complete the following steps =>If the fuel distribution pipe (high-pressure rail) was removed =>
6. 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.
6.1. 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
Blowing out high-pressure line
6.2. Drain residual fuel from the high-pressure distribution pipe before fitting it. Shake the high-pressure pipe over a cloth to do this.
7. Fit high-pressure distribution pipe (high-pressure rail) and tighten it to the correct tightening torques. => 243019 Removing and installing fuel distribution pipe (fuel rail) on DFI engines - section on "Installing"
CAUTION
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 leak in the system.
Building up pressure
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 => 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
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.
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
Blowing out high-pressure pump
12. Screw high-pressure line correctly to the high-pressure pump. => 246319 Removing and installing DFI high-pressure pump - section on "Installing"
CAUTION
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 -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 leak in the system.
Building up pressure
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) => Leak. 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 fuel line. To do this, fit fuel supply line (low pressure) onto marking correctly. Counter while doing this.=> Tightening torque: 35 Nm (26 ftlb.)
3. Fit engine cover. For details, see => 700219 Removing and installing front trim (engine compartment) - section on "Installing"
4. Fit fuses or connect battery.
5. Bleed the fuel high-pressure system. => 2430B1 Filling and bleeding DFI fuel high-pressure system (includes bleeding fuel distribution pipe)