Mechanics

Brake Flex Hose Replacement

How to Replace a Brake System Flex Hose

Every car has a brake flex hose, this hose is needed because the suspension's horizontal and vertical movement during normal vehicle operation. This brake flex line is mounted on the frame of the car, usually with two brake flex hoses in the front and one or two in the rear of the car. Like any rubber based part these hoses are subjected to road conditions and must be replace when signs of failure arise. When a brake hose fails it will leak brake fluid and cause the brake system to run low on brake fluid causing the brake fluid warning light to illuminate. Anytime you replace a brake system flex hose the brake system must be bled to relieve any bubbles that are trapped. If air bubbles remain in the system it will cause the brake pedal to feel spongy. Before we begin open the car's hood and observe the brake fluid level.

Park your car on level ground with the engine off and the emergency brake on. Always raise a car according to the manufacturers recommended instructions and secure with jack stands. Also we will be dealing with brake fluid so be sure to wear protective clothing, eyewear and gloves.

Tools Needed to Complete this Job

1. Lug wrench

2. Line wrench set

3. Large standard blade screw driver

4. Wrench set

5. Socket wrench set
 

Parts and Supplies needed to Complete this Job

1. Replacement brake flex hose

2. Shop towels

3. Brake fluid
 

Instructions

Step 1 - First remove wheel cover or hub cap. (some cars have the lug nuts exposed, if so skip to the next step)

Step 2 - Loosen one turn and (do not remove) the lug nuts of the wheel to be serviced.

Step 3 - Lift and support car in a safe position high enough to remove the brake flex hose. A jack is used in most cases, supported by jack stands.

Step 4 - Now remove the remaining lug nuts and remove the wheel.

Step 5 - Loosen the hydraulic brake flex hose at the caliper or junction block, do not remove.

Step 6 - Loosen the flex hose at the frame or body mount and remove the retainer clip.

Step 7 - Continue removing the hydraulic brake flex hose by completely removing the flange nuts or bolts. (note: in some cases a copper sealing washer is used between the hose and caliper or mounting block).

Step 8 - Completely clean all mounting and sealing surfaces.

Step 9 - Re-install new brake hose using new copper sealing washers.

Step 10 - Tighten all mounting bolts and flange nuts to seal the new brake hose.

Step 11 - Bleed the brake system as needed.

Step 12 - Inspect brake flex hose connection for leaks and repair as needed.

Step 13 - Reinstall wheel and lug nuts, lower the tire onto the ground the finish tightening lug nuts to manufactures torque specifications.

Check the brake pedal operation, it should be normal. Do not move the vehicle until normal brake operation has resumed
 

Common Problems

  • Trapped air in the brake system.
  • When replacing a brake flex hose make sure the copper sealing washer is not leaking.
  • If a brake flex hose fitting has seized, use an anti-rust solvent such as wd40 or equivalent to help loosen.
If further assistance is needed, our certified car repair technicians are ready to answer your car questions. Also, gain manufacturer specific instructions and information by clicking - Auto Repair Manual

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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-08-16)