Fuel Injector: Service and Repair
WM 244019 Removing and installing high-pressure fuel injector (DFI)
Tools
Technical values
Preliminary work
1. Read out engine control unit fault memory before getting started and print log.
2. Switch off the ignition and all loads when working on the fuel system.
3. Disconnect the battery.
4. Remove intake-air distributor (intake module). -> 244619 Removing and installing intake-air distributor on DFI engines - section on "Removing" Overhaul
5. Pull cable plugs off the injectors.
6. Remove both high-pressure distribution pipes (fuel rails) for all injectors. -> 243019 Removing and installing fuel distribution pipe (fuel rail) on DFI engines - section on "Removing" Service and Repair
Information
Component overview
DFI injection system, 3.6 l
Removing high-pressure fuel injector
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
- 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.
- Do not use any sealant containing silicone or silicone spray when the injection system is open. Traces of silicone drawn in by the engine are not combusted and damage the oxygen sensors.
Information
The tool numbers refer to the individual parts of the tools in the repair kit T10133 and the supplement set T10133/11-15 (unless indicated otherwise).
1. Pull injector out of the cylinder head by hand (using a glove.). Turn injector slightly if necessary.
If the injector is stuck in the cylinder head due to coking of the injector tips, proceed as follows:
2. Pull upper O-ring on the injector upwards by hand as shown => Fuel injector sealing rings and remove it. Use a small screwdriver to help, if necessary.
Fuel injector sealing rings
3. Bolt impact hammer no. 3 to puller no. 15 -1-.
Fuel injector impact hammer
4. Fit impact hammer with puller no. 15 into the groove -arrow- on the fuel injector.
Groove on fuel injector
5. Tap gently on the fuel injector to remove it. Use impact hammer -1- and puller -2- as shown.
Pulling out fuel injector
Replacing Teflon sealing ring on high-pressure fuel injector
NOTICE
Incorrect handling of injectors
- Leaks in combustion chamber
-> Teflon sealing rings must always be replaced after removal and before refitting injectors.
-> Do not replace Teflon sealing rings until just before fitting the injector.
-> Install injector immediately after replacing the Teflon sealing ring.
Information
The tool numbers refer to the individual parts of the tools in the repair kit T10133 and the supplement set T10133/11-15 (unless indicated otherwise).
Installation position of Teflon sealing ring: -arrow-
Teflon sealing ring
1. Remove high-pressure fuel injector.
2. Replace large sealing ring for long fuel injectors for cylinders 1, 3 and 5.
3. Clean fuel injector carefully using a plastic brush (or cloth) and acetone or solvent naphtha. Hold sealing ring gently using pointed-nose pliers and carefully pull off Teflon sealing ring -1-. Do not scratch valve body.
Removing Teflon sealing ring
4. Also clean sealing ring groove in the area of the sealing ring. Remove any deposits (coking).
5. Place new sealing ring -2- onto mounting cone no. 5 -1-.
Teflon sealing ring on mounting cone
6. Using assembly sleeve no. 6 (knurled side facing the sealing ring) -3- push sealing ring gently as far as it will go onto mounting cone no. 5 => Teflon sealing ring on mounting cone.
7. Turn assembly sleeve no. 6 -3- around (knurled side now no longer facing sealing ring), and push sealing ring -2- onto the end of mounting cone no. 5 -1-.
Assembly sleeve turned around
8. Place mounting cone no. 5 -1- with sealing ring onto the fuel injector from the front. Using assembly sleeve no. 6 -2- push sealing ring further onto the fuel injector.
Fitting Teflon sealing ring
The Teflon sealing ring is not yet seated in its groove.
9. Remove assembly sleeve no. 6 and mounting cone no. 5. Push sealing ring into the ring groove using assembly sleeve no. 6.
Calibration (shaping) of Teflon sealing ring:
9.1. Push spacer sleeve no. 11 -1- onto the valve body.
Spacer sleeve
9.2. Press calibrating sleeve no. 7 -2- over the sealing ring until it stops against spacer sleeve no. 11.
9.3. Pull off calibrating sleeve no. 7 again.
9.4. Press calibrating sleeve no. 8 -4- over the sealing ring until it stops against spacer sleeve no. 11 -3-.
Calibrating sleeve
9.5. Pull off calibrating sleeve no. 8 again.
The Teflon sealing ring now has the correct installation dimension.
10. The injector should now be installed immediately, as the Teflon sealing ring will soon start to swell (prevents leaks when installed).
Installing high-pressure fuel injector
NOTICE
Incorrect handling of injectors
- Leaks in combustion chamber
-> Teflon sealing rings must always be replaced after removal and before refitting injectors.
-> Do not replace Teflon sealing rings until just before fitting the injector.
-> Install injector immediately after replacing the Teflon sealing ring.
Information
The tool numbers refer to the individual parts of the tools in the repair kit T10133 and the supplement set T10133/11-15 (unless indicated otherwise).
1. Clean bores for fuel injectors in the cylinder head thoroughly using the nylon brush no. 4 -arrow-. Coat brush with acetone or solvent naphtha.
Cleaning bore in cylinder head
2. Check plastic support washer for damage and replace it if necessary.
To replace the damaged plastic support washer:
2.1. Remove O-ring -3-.
Removing O-ring
2.2. Cut open support washer -2- using small side cutters and remove it.
2.3. Pull off spring element for fuel injector -1- and slide on tab washer no. 12 -1- instead.
2.4. Push new support washer -3- on to mounting cone no. 13 -2- and fit it on the fuel injector as shown.
Replacing support washer
2.5. Push the support washer -3- using calibrating sleeve no. 14 (knurled side facing the fuel injector) -4- on to the fuel injector as far as the first groove -arrow-.
2.6. Turn calibrating sleeve no. 14 -3- around (knurled side no longer facing fuel injector).
Calibrating sleeve
2.7. Push calibrating sleeve -3- over the support washer -2- in direction of arrow until it stops against tab washer no. 12 -1-.
2.8. Remove calibrating sleeve no. 14 again. The support washer now has the correct installation dimension.
3. Replace O-ring -3- , Teflon sealing ring and spring element for injector -1-. Fit a new spring element - and a new O-ring - in front of the support washer instead of tab washer no. 12. Replace Teflon sealing ring -> 244019 Removing and installing high-pressure fuel injector (DFI) - section on "Information".
Spring element, O-ring
4. Immediately install injector into the cylinder head at the correct installation position. To do this, insert the grease- and oil-free injector into the clean cylinder bore.
Subsequent work
1. Fit high-pressure distribution pipes (fuel rails). -> 243019 Removing and installing fuel distribution pipe (fuel rail) on DFI engines - section on "Installing" Service and Repair
2. Connect cable plugs for injectors.
3. Fit intake-air distributor (intake module). -> 244619 Removing and installing DFI intake-air distributor - section on "Installing" Overhaul
4. Connect the battery.
5. Perform a test drive. Make sure the high-pressure pipes and threaded joints are sealed properly (visual inspection with engine running).
6. Read out engine control unit fault memory after completing the work and print log. Compare with the previous log.