VW Passat & Audi A4 1990-2000

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.
  3. Using a flare nut type wrench, loosen the flare nut.

To install:

  1. Installation is the reverse of the removal procedure.