How to Repair a Rusted Brake Line

by Don BowmanUpdated July 18, 2023
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There are two ways to repair a rusted brake line in your automotive and it all depends on how much of the car brake line is rusted and where in the brake system it is. If the vehicle has been up north and the salt has gotten to it to the extent that most of it is rusted, a whole brake line replacement is necessary. If, by chance, there is just one section, such as the front brakes or the rear brakes, then doing a splice and replacing just a piece would be the easy, safe solution.

Leaking brake lines are auto parts that need to be addressed immediately when auto repair is happening. Brake pedals and brake pipes are extremely important, and the brake caliper of a car will determine if the parking brake will be effective or not. Steel brake lines are sturdy, but susceptible to rusting, so be sure to get some jack stands and check them out every once in a while.

Things You Will Need

  • Tubing bender tool
  • Length of brake line consistent with the one that is to be replaced.
  • Tubing cut off tool
  • Set of ¼-inch set of sockets
  • ¼-inch ratchet
  • Set of wrenches
  • Set of line wrenches
  • Can of penetrant
  • Two compression fittings
  • Tape measure

1. Look the line over for the extent of rust

Look the line over for the extent of rust. If the line has anything more than surface discoloration, there is corrosion and the rusty brake lines should be replaced. If all the brake pads are rusty, measure the length of the line from one end where it is attached to the other. Always add a foot for error when bent and for cutting during brake line repair. If the entire line is to be replaced, after measuring, soak the fittings to be removed with a penetrant for about 15 minutes. It may be necessary to soak them several times to get the brake tubing out.

2. Remove all the brackets holding the brake line

Use the sockets and ratchet to remove all the brackets and flare nuts holding the brake line to the frame. Each bracket has one screw.

3. Remove the brake line fittings

Using the line wrenches, remove the brake line fittings if you are replacing the whole line. If you are replacing one section, then cut the section of the line out with the tubing cutter. To use the tubing cutter, put it around the line and tighten the screw. Rotate the cutter one turn and further tighten the screw. Continue this process until the line is cut.

4. Lay the old brake line on the floor

Lay the old brake line on the floor. Use the tubing bender and make the new brake line have the same bends as the old one. When the brake line looks the same as the rusted one, attach it to the vehicle using the line wrenches to tighten the fittings. Replace the hold-down brackets to keep the line in place.

5. Cut any excess brake line

Cut any excess brake line using the tubing cutter as before. Take the compression fittings apart. There will be two end caps with a hole in the center for the line, two ferrules that resemble a wedding ring, and a center tube with threads on both ends. Place one of the end caps on the line. Place the ferrule over the end of the line. Hold the center tube or barrel in one hand and the line with the cap and ferrule in the other. Push the line into the barrel and screw the cap onto the barrel--it will collapse the ferrule around the line and lock the line into the barrel with a leak proof seal. Hold the barrel with one wrench and tighten the end cap with a second wrench.

6. Place the other cap and ferrule on the cut line

Place the other cap and ferrule on the cut line on the vehicle. Push the new line with the ferrules and caps onto the old line. While pushing, draw the cap on the old line tight on the barrel. Now it is in place--do the same for the other side.

7. Fill the master cylinder reservoir with brake fluid

Fill the master cylinder reservoir with brake fluid. Bleed the brakes with a helper. Start the car and loosen the brake bleeder screw on the passenger rear wheel. Tell the helper to push the pedal to the floor to get the rotors going and hold it there. When the pedal is to the floor, close the bleeder valve. Now tell him to let the pedal up. Repeat this process until nothing but fluid comes out of the line--no air. Do the passenger rear and then move to the driver's rear, then passenger front and driver's front.

And if you don’t want to DIY a fix for your Honda or Dodge by looking up a full video online or having to buy tools or a flaring kit on Amazon to fix your brake hose, you can always go to a mechanic.

Video: How to Replace a Rusty Section of Brake Line

Helpful comments from the video:

  • Buy a double flare kit, read the instructions or you can buy the double flare inserts for the flare tool you already have (they are standard) and youtube how to double flare. If you have rusting lines get ready to do all of them sooner than later, advice from the rust belt.
  • You should always double flare hydraulic steel break lines
  • All high pressure fittings need to be double flared. Propane lines, brake line, gas lines, nitrogen lines, ammonia lines, get the drift.

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