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4
General repair instructions
4.1
Rules for cleanliness when working on
fuel supply system and injection system
Even small amounts of dirt can cause malfunctions. When work‐
ing on the fuel supply system and injection system, it is therefore
important to observe the following basic rules:
♦ Carefully clean connection points and the surrounding area
with engine cleaner or brake cleaner and dry thoroughly before
opening.
♦ Seal off open pipes/lines and connections immediately with
clean plugs, e.g. from engine bung set - VAS 6122- .
♦ Place parts that have been removed on a clean surface and
cover them over. Do not use fluffy cloths.
♦ Carefully cover or seal open components if repairs cannot be
carried out immediately.
♦ Only install clean components; replacement parts should only
be unpacked immediately prior to installation. Do not use parts
that have been previously unpacked and stored away loose
(e.g. in toolboxes, etc.).
♦ When the system is open: Do not work with compressed air.
Do not move the vehicle unless absolutely necessary.
♦ Protect unplugged electrical connectors against dirt and mois‐
ture and make sure connections are dry when attaching.
4.2
Checking for leaks in the fuel system
– Allow engine to run for several minutes at moderate rpm.
– Switch off ignition.
– Check complete fuel system for leaks.
– If leaks are found although the connections have been tight‐
ened to the correct torque, the relevant component must be
renewed.
– Road-test vehicle and accelerate with full throttle at least once.
– Then inspect high-pressure section of fuel system again for
leaks.
4.3
Foreign particles in engine
♦ When working on the engine, all open inlet and exhaust ports
must be sealed with suitable plugs (e.g. from engine bung set
- VAS 6122- ) to prevent foreign particles from entering the
engine.
♦ In the event of mechanical damage to one of the cylinder
banks, the intake and exhaust systems and combustion cham‐
bers of the opposite cylinder bank must always be examined
to prevent further damage occurring later.
4.4
Contact corrosion!
Contact corrosion can occur if unsuitable fasteners are used (e.g.
bolts, nuts, washers, etc.).
For this reason, only fasteners with a special surface coating are
used.
Audi A8 2003 ➤
10-cylinder direct petrol injection engine (5.2 ltr. 4-valve), mechanics - Edition 10.2013
4. General repair instructions
5