If your vehicle brake response is slow, you notice a colorless fluid under the vehicle, or your dash light comes on, you may have a brake fluid leak. Steel brake lines are prone to corroding, especially from salt on the road during the winter. 

A leaking brake line should be fixed as soon as possible. It is easy to replace a leaky steel brake line by following these tips.

Prepare to Fix the Leak

To repair the leak, gather: 

  • work gloves
  • rags
  • floor jack and jack stands
  • wheel chocks or bricks
  • flat blade screwdriver
  • line wrench
  • pliers
  • rust remover
  • flare tool
  •  tube cutter
  • brake lines
  •  bleeding kit

Shut off the engine, and let it cool. Prop the hood open, and look for the fluid reservoir, which is commonly near the back of the engine compartment. Check the brake fluid level. A low fluid level is often a good sign of a brake line leak. 

If there is fluid under the vehicle, lay newspaper over the area. Verify the leak by pressing on the brake, then look under the vehicle for wet spots.

Remove the Old Brake Line

If you suspect a brake line leak, raise the vehicle up with the floor jack, then lower it on the stands. Set wheel chocks or bricks against the wheels to keep them from rolling off the stands.

Spray rust remover on the brake line bolts, wait several minutes, then remove the bolts with the line wrench. Use a flat blade screwdriver to remove line fasteners. Wipe any fluid with rags to prevent paint corrosion. You may also cut brake lines with a tube cutter if there is no rust.

Install the New Brake Lines

You will need two compression fittings for each line. Detach the brake line fitting caps; being careful to keep the ferrule (metal cap or band) intact. 

Measure the old brake line, and use it as a guide to cut a new line with the tube cutter; adding an additional half inch. Set the tube in the flare tool, and file the ends flat t make a good seal. Smooth burrs with a razor blade. 

Attach the fittings, and follow instructions to double flare or bubble flare the line. Avoid a single flair on steel brake lines. 

Rub some brake fluid on the end of the tube to keep contaminants out of the system. Flare the other end of the tube, attach fittings, and bend lines to closely match the original. Connect the lines by hand first, and tighten connections with a wrench.

It is ideal to bleed the whole brake system after replacing the brake lines. Remove the vehicle from the jacks, and take it for a test drive. If the brakes still don't operate properly, or you feel you can do the job, see an auto servicing mechanic.