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How to replace Fuel Lines & Fittings on Audi A4 & VW passat models?

The procedure to replace fuel line fitting is as follows.
Fuel Lines & Fittings Removal & Installation details are mentioned below:-----

BANJO BOLT FITTINGS
CLAMPED FITTINGS
COMPRESSION FITTINGS

Details for all 3 are mentioned:----


Banjo Bolt Fittings



The banjo bolt fitting has a hollow bolt that is installed through a round hollowed out chamber with a hose fitting incorporated onto the chamber. The hollowed out chamber and hose fitting resemble the shape of a banjo, hence the name banjo bolt. The banjo bolt uses a sealing washer on each side of the hollowed chamber that should be replaced during reassembly.
Banjo bolt fittings are used where the fluid in the fluid lines is under pressure.
  1. To remove a banjo bolt type of fitting, secure the component to which the banjo bolt is threaded and loosen the banjo bolt, using a boxed-end wrench.
To install:
  1. Using new sealing washer on either side of the banjo fitting, install the banjo bolt and carefully tighten to specification. The sealing washers should be slightly 'crushed' between the banjo bolt the banjo fitting and the component.


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Fig. The outlet line of on a firewall mounted fuel filter uses a banjo bolt type fitting. Always use new sealing washers when reinstalling the banjo bolt


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Fig. Fuel line banjo bolt and line-Fox

Clamped Fittings



The conventional clamped fitting is used when a flexible hose is installed over a fitting and clamped in place. This type of fuel fitting is found in a variety of locations and sizes throughout the vehicle, such as the fuel filler neck and evaporative canister hoses. The flexible fuel hose is installed over a fitting with a clamp to secure the hose to the fitting. The clamp is either spring loaded and released using pliers, or mechanically tightened, requiring a screwdriver or related tool to loosen or tighten.
  1. To remove a clamped type fitting release the clamp's tension and carefully slide the clamp off the section of hose that is attached to the fitting.
To install:
  1. Carefully slide the hose over the fitting.
  2. Center the clamp over the middle of the section of hose covering the fitting.
  3. Release the clamp or tighten as necessary.


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Fig. The mechanically tightened clamp should be centered on the fitting and properly secured. Use care to not over-tighten


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Fig. The spring-loaded clamp is released by using flat-nosed pliers to squeeze the tabs together and slide the clamp off the clamped portion of the fitting

Compression Fittings



The compression fitting has a flared metal tube or a compression fitting that is surrounded by a threaded flare nut. Because the tube is flared or has a compression fitting installed, the threaded flare nut cannot be removed from the line and is considered part of the assembly.
Compression fittings are most often used when a pressure line attaches to an assembly, much like the fluid lines found at the brake master cylinder or on the inlet fuel line for the firewall mounted fuel filter.
The compression fitting does not have a gasket or seal, rather it uses the threaded flare nut to seal the flared end of the line or a compression fitting on the line to the assembly. The flared end of the fuel line or the compression fitting is sealed between the component and the flare nut.
A compression fitting is most often found where the fluid in the line is under considerable pressure.
  1. To disconnect a fuel line using a compression fitting, securely hold the component to which the flare nut is threaded.
  2. Using a flare nut type wrench, loosen the flare nut.
To install:
  1. Installation is the reverse of the removal procedure.


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Fig. An example of an internally threaded flare nut on this fuel line. Note the use of a flare nut wrench loosen the nut while the component is held with another wrench


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Fig. The open-end wrench on the left compared to a flare nut wrench on the right. The slot allows the flare nut wrench to clear the line, yet will grip the flare nut on all 6 sides


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Fig. An externally threaded flare nut is used on both fuel lines and hydraulic brake lines. A flare nut wrench is shown loosening the flare nut on a hydraulic brake line fitting


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Fig. The fuel inlet line on a firewall mounted fuel filter is a compression fitting. The flare nut has external threads and is threaded into the bottom of the fuel filter


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Fig. An exploded view of the firewall mounted fuel filter and mounting bracket. The filter outlet (top) uses a banjo bolt fitting, the inlet (bottom) is a compression fitting



These details will help.
Thanks.

FOR MORE HELP GO TO: ---

Car repair guide?

http://technoanswers.blogspot.in/2012/03/car-repair-guide.html



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