Fuel Rail: Service and Repair
WM 243019 Removing and installing fuel distribution pipe (fuel rail) on DFI engines
Technical values
Preliminary work
1. Remove high-pressure pump. => 246319 Removing and installing DFI high-pressure pump - section on "Removing"
2. Remove intake-air distributor. The lower fuel distribution pipe must be removed during disassembly. => 244619 Removing and installing intake-air distributor on DFI engines - section on "Removing"
Information
Component overview
DFI injection system, 3.6 l
Removing fuel distribution pipe (fuel rail)
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.
Cylinders 1, 3 and 5
1. Disconnect fuel low-pressure line at the transfer point on the plenum panel or directly on the fuel rail. Counter while loosening the line. -1-
Fuel rail for cylinders 1, 3 and 5
2. Remove four screws on fuel rail for cylinders 1, 3 and 5 -2-. Hold fuel rail with both hands and pull out by joggling it. Make sure not to pull the injectors out of the cylinder head. If the injectors slip out of the cylinder head accidentally, the Teflon sealing rings must be replaced. => 244019 Removing and installing high-pressure fuel injector (DFI) - section on "Information"
3. Replace the sealing rings between the injectors and the fuel rail.Cylinders 2, 4 and 6
4. Remove intake-air distributor. The lower fuel distribution pipe (fuel rail for cylinders 2, 4 and 6) must be removed during disassembly. => 244619 Removing and installing intake-air distributor on DFI engines - section on "Removing"
5. Replace the sealing rings between the injectors and the fuel rail.
Installing fuel distribution pipe (fuel rail)
Cylinders 1, 3 and 5
1. The sealing rings between the injectors and the fuel rail must be replaced. For details of other components to be replaced or checked, see => 244019 Removing and installing high-pressure fuel injector (DFI)
2. Coat the sealing rings between the injectors and the fuel rail with clean engine oil.
3. Hold fuel rail with both hands and press into position by joggling it. Make sure that the injectors slide correctly into the bores on the fuel rail. Fit four new screws on the fuel rail for cylinders 1, 3 and 5. -2- => Tightening torque: 30 Nm (22 ftlb.) , then => Torque angle: 90°
Fuel rail for cylinders 1, 3 and 5
4. Fit fuel low-pressure line at the transfer point on the plenum panel or directly on the fuel rail. Always counter while fitting. Fuel line to fuel rail => Tightening torque: 22 Nm (16 ftlb.) ; fuel line to fuel line at plenum panel transfer point => Tightening torque: 35 Nm (26 ftlb.) Cylinders 2, 4 and 6
5. The sealing rings between the injectors and the fuel rail must be replaced. For details of other components to be replaced or checked, see => 244019 Removing and installing high-pressure fuel injector (DFI)
6. Coat the sealing rings between the injectors and the fuel rail with clean engine oil.
7. Fit intake-air distributor. The lower fuel distribution pipe (fuel rail for cylinders 2, 4 and 6) must be fitted during assembly. => 244619 Removing and installing DFI intake-air distributor - section on "Installing"
Subsequent work
1. Fit intake-air distributor. The lower fuel distribution pipe must be fitted during assembly. => 244619 Removing and installing DFI intake-air distributor - section on "Installing"
2. Fit high-pressure pump. => 246319 Removing and installing DFI high-pressure pump - section on "Installing"