12:15. Survey and replacement of brake lines and hoses of hydraulic system of brakes

Brake fluid is poisonous. It also strongly dissolves paint. See the Prevention at the beginning of the Section Pumping of Hydraulic System of Brakes.


Through the certain periods specified in the Size table and adjusting data at the end of the Management it is necessary to examine brake lines and hoses. Поддомкратив the car and having reliably installed it on axial support, check flexible hoses for existence of cracks, wear of an external cover, leak of liquid, attritions and other damages. Hoses are an important and vulnerable part of the brake system therefore survey has to be very careful. Metal tubes should be checked for existence of deep cavities and corrosion. If on a hose or a tube the above described defects were found, replace them.

For careful check of hoses and tubes it is useful to use a small lamp and a mirror.

Replacement of flexible hoses


  1. Purify all dirt since the ends of a hose. Prepare a suitable container for collecting sprayed at a liquid hose detachment.
  1. To disconnect a hose from the chassis, release a nut on a metal brake tube, holding at the same time six-sided nipple connection on the end of a flexible hose (the lower right arrow) by means of a cutting cap ("brake") wrench (the top right arrow). If the nut does not give in, moisten it with oil. After a hose detachment from the line remove a spring clip (the left arrow) from an arm and then disconnect a hose from an arm.
  1. To disconnect a flexible hose from a support, just give fastening screws. If the hose any time is disconnected, stop up nipple connections on a support to prevent dirt hit.
  2. You make installation upside-down. Make sure that arms are not damaged and lock-nuts are reliably tightened. If spring clips weakened, replace them.
  3. Attentively
  4. double-check whether components of a suspension bracket or system of steering adjoin to hoses. During check ask the assistant to turn a steering wheel from an emphasis against the stop.
  5. Pump over the brake system as it is described in the Section Pumping of Hydraulic System of Brakes.

Replacement of metal brake lines

When replacing brake lines use only original details - it is desirable from the dealer of BMW.

The original brake BMW lines are delivered directly. To give them the necessary form, you will need adaptation for are flexible tubes.


  1. At first pick up the phone which you are going to replace, put it on a pure workbench and carefully measure. Prepare a new tube of the same size and bend it in a form old.

Do not bend and do not damage the line. Bend radius never has to be less than 14 mm. Make sure that the sheeting on the new line is not damaged on bends.

  1. At installation of the new brake line make sure that it is reliably propped up by arms that its route coincides with initial and that it is at sufficient distance from the moving and heating up components.
  2. After installation check the level of brake fluid in the main cylinder and add it if necessary. Pump over the brake system as it is described in the Section Pumping of Hydraulic System of Brakes and check work of brakes before operation of the car. Make sure of lack of leak of liquid.