Fuel Rail: Testing and Inspection
WM 243001 Checking fuel distribution pipe (fuel rail) on DFI engines for leaks
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.
- The two high-pressure fuel distribution pipes beneath the intake-air distributor must be fitted with new sealing rings, carefully and in clean conditions. Once fitted, these cannot be inspected visually.
1. Remove rear engine compartment cover. -> 700219 Removing and installing front trim (engine compartment) - section on "Removing" Service and Repair
Information
Component overview
DFI injection system, 3.6 l
Checking fuel distribution pipe (fuel rail) for leaks
WARNING
Leaking fuel supply lines
- Emerging fuel
- Risk of fire
-> Perform leak test.
1. Inspect lines at and around the high-pressure pump for leaks when the engine is idling after the test drive. -1 to 8- Unclip wiring harness if necessary. => Wiring harness
Wiring harness
View of threaded connections in high-pressure system
2. When the engine is idling, inspect the fuel lines for leaks using a mirror and a lamp. -1 to 8-
Subsequent work
1. Fit engine cover. For details, see -> 700219 Removing and installing front trim (engine compartment) - section on "Installing" Service and Repair
2. Bleed the fuel high-pressure system. -> 2430B1 Filling and bleeding the DFI fuel high-pressure system (includes bleeding fuel distribution pipe) Service and Repair