Fuel Injector: Service and Repair
Fuel Injection Unit
Special tools, testers and auxiliary items required
• Puller (T10055) with adapter (T10055/1)
• Assembly sleeve (T10377)
• Socket (T40055)
• Torque Wrench (V.A.G 1331)
• Ratchet (V.A.G 1331/1)
CAUTION!
• Follow the safety precautions when working on the diesel direct injection system. Refer to --> [ Safety Precautions ] Safety Precautions.
• Observe rules for cleanliness. Refer to --> [ Clean Working Conditions ] Clean Working Conditions.
Always follow these instructions before and during work.
Removing
- Remove engine cover. Refer to--> [ Engine Cover ] Engine Cover.
- Remove protective strip --> [ 1 Protective Strip ] Removal and Replacement.
- Disconnect connector - 1 - at the fuel injectors to be removed.
- Before removing, clean the return line connection on the fuel injectors that will be removed (for example using a commercially available detergent).
- Dry return line connection.
- Cover return line connection with a rag.
- Disconnect fuel return line connections at the fuel injectors that will be removed. Pull them upward to release them - arrow -.
• Maintain clean working conditions. Dirt and contaminants must not enter the return lines and the connections on the fuel injectors.
- Remove high pressure line --> [ 5 High Pressure Lines ] Removal and Replacement between the rail element (high pressure reservoir) and fuel injectors that will be removed.
- Remove bolts in the cover --> [ 18 Injection Unit Cover ] Removal and Replacement on the fuel injector that will be removed.
- Raise cover slightly and rotate it 90° to free up the fuel injector nuts.
CAUTION!
When removing the fuel injector nuts, the nut could fall into the cylinder head. Work very carefully to avoid unnecessary work or damage.
- Remove nuts on the corresponding fuel injector.
- Position puller (T10055) with the adapter (T10055/1) as illustration and remove the fuel injector upward by tapping.
Installing
Important Information on Installing Fuel Injectors
• Replace the following components and seals or O-rings each time they are removed: Tensioning bracket, copper disc, fuel injector duct O-ring and fuel injector return line O-ring.
• Replace the following components and seals or O-rings when replacing the fuel injector: Tensioning bracket, injection line, copper disc, fuel injector duct O-ring and fuel injector return line O-ring.
• When installing, the fuel injectors and high pressure lines may only be installed on the same cylinder as before.
• Do not change the angles of the high pressure lines.
• Check the fuel injectors and installation locations for contamination before assembling.
• The fuel injectors must not have any damage.
• Lubricate all of the O-rings with assembly oil or engine oil before installing.
If a used fuel injector is installed:
- Spray tip of the fuel injector with a rust removing spray. Remove rust or oil particles with a rag after approximately 5 minutes.
- To remove the used copper sealing ring from the fuel injector, clamp the sealing ring carefully in a vise until the clamping jaws on the vise prevent the ring from turning. Pull fuel injector out of the copper sealing ring by hand with slight twisting and pulling motions.
- Install new copper sealing ring with a plastic bushing.
- To avoid damaging the O-ring, slide new O-ring - 2 - for the fuel return line connection over the assembly drift - 1 -.
- To remove rust particles on the fuel injector sealing surface, clean the fuel injector duct in the cylinder head with a cloth dampened with engine oil or rust remover. Do not damage the sealing flanges.
- Replace fuel injector duct seal using the assembly drift (T10377).
- Slide fuel injector cover on.
- Slide clamping bracket onto the fuel injector and make sure it is positioned correctly.
- Insert fuel injector in the duct.
CAUTION!
When installing the fuel injector nuts, the nut could fall into the cylinder head. Work very carefully to avoid unnecessary work or damage.
- Position tensioning bracket nuts carefully and tighten them by hand:
• Tightening specifications --> [ (item 17) 10 Nm ] Removal and Replacement.
- Rotate fuel injector cover into the installation position and tighten it:
• Tightening specifications --> [ (item 19) 5 Nm ] Removal and Replacement.
- Tighten union nuts for the high-pressure lines by hand.
- Make sure the high-pressure lines are seated free of stress.
- Use torque wrench (V.A.G 1331) with the ratchet (V.A.G 1331/1) and socket (T40055) to tighten the high pressure lines.
• Tightening specifications --> [ 5 High Pressure Lines ] Removal and Replacement.
- Press return line connections carefully over the sealing ring onto the fuel injector (check the sealing ring first for damage). The connection must engage audibly. Then press the release pin down carefully.
• After replacing one or more fuel injectors, the "injector quantity calibration" and "injection pressure calibration" for the new fuel injectors must be programmed in the ECM. "Guided Functions ".
- Fill fuel system. Refer to --> [ Fuel System, Filling ] Fuel System, Filling.
- Let engine run at idle a few minutes.
- Switch off ignition.
- Check entire fuel system and return line connections for leaks.
If there are leaks despite correct tightening specifications, replace the affected component.
- Then perform a road test that is longer than 20 km and where the accelerator is pressed down completely at least one. Then check the high pressure again for leaks.
• Observe safety precautions that apply to road tests.. Refer to --> [ Safety Precautions ] Safety Precautions
• If there is still air in the fuel system, the engine may switch to emergency mode during the road test. Stop the engine and erase all DTC entries.
- Then continue the road test.
- Install protective strip --> [ 1 Protective Strip ] Removal and Replacement.
- Install engine cover. Refer to --> [ Engine Cover ] Engine Cover.