A: The brake hydraulic system consists of flexible rubber hoses connecting the Wheel Cylinders or calipers and the rear axle fitting to metal lines running along the frame. If an inspection reveals a problem with a rubber hose or metal line, it must be replaced immediately for continued safe use of the vehicle. Before replacing a line or hose, determine the cause of failure and remedy it to prevent future failures. Components such as exhaust pipes can come loose and rub against the line, causing breaks or tears. Replacement steel and flexible brake lines can be found at dealer parts departments and auto parts stores. It is important to use genuine steel or approved flexible brake hoses as replacement items. When removing a brake line or flare-nut hose fitting, always use the proper flare-nut wrenches for loosening and tightening connections. Steel brake lines are usually held in place with clips, which should be completely removed before replacing the supported brake line. These clips provide support and prevent vibration that can lead to line fatigue and breakage. After replacing a line, the hydraulic system must be bled to remove any air bubbles.