How To Fix A Leaking Brake Line Fitting? new for 2022

Today we are going to talk about how to fix a leaking brake line fitting. If you are having any problems with your brake line, please do not hesitate to call us. In this post, We would be happy to help you out.

how to fix a leaking brake line fitting
how to fix a leaking brake line fitting


Why Do Brake Lines Fail at the Flare?

Why Do Brake Lines Fail at the Flare?
Why Do Brake Lines Fail at the Flare?

Brake lines can leak when there is a poor connection between the seat of the fitting and the brake line. This type of leak is commonly known as weep.

Despite using various flare tools, I was never able to achieve a clean, concentric finish on my flares that would allow the flare to seat properly with the fitting. Furthermore, regardless of which type of lines I used, the finished product always looked inconsistent and lacked precision. On the left you can see tiny imperfections on the flare. The flare on the right has a “lapped” finish.

Why Do Brake Lines Fail at the Fitting?

Why Do Brake Lines Fail at the Fitting?
Why Do Brake Lines Fail at the Fitting?

A leaking flare connection can be caused by a number of things, but often the problem is with the flare itself. If the fitting is damaged in some way, it can become very difficult to fix.

Sealing Flare Fitting Connections

Sealing Flare Fitting Connections
Sealing Flare Fitting Connections

Lapping is a common practice that has been used for 100 years. Even with the best equipment, mechanics always lapped engine valves to ensure they wouldn’t leak. Recently, I thought of applying this practice to flared tubing and it fixed my leak.

how to lap flared tubing

1. Unscrew the brake line from the fitting.
2. Clamp the line with the appropriate-sized collet.
3. Attach it to the Surseat lap tool.
4. Before using the lapping head, spray it with lubrication.
5. 6-10 times, rotate the lapping head back and forth.
6. Inspect and clean the flare. The finish should be smooth and concentric. If not, go back to step 5.
7. Remove the Surseat’s brake line and reattach it to the fitting.
8. Check the seal and bleed the brakes.

How to resurface fittings

1. Insert the fitting via the Fitting Fixer guide.
2. Connect the lapping head to the handle of a drill or tap.
3. Spray some lubrication into the lapping head cavity.
4. Place the lapping head over the fitting and into the guide.
5. Spin the lapping head on the fitting, releasing every 2-3 seconds to avoid clogs.
6. Remove the fitting and check the surface after 5-6 passes. Repeat step # 5 if required.

How to Check for a Leak Where the Flare Joins the Fitting

How to Check for a Leak Where the Flare Joins the Fitting
How to Check for a Leak Where the Flare Joins the Fitting

If your brake or fuel line is out of your vehicle, there is an easy way to determine if there’s a leak at the fitting.

To check the pressure in a tube, you can either screw in a cap flared tube nut or purchase an Earl’s Performance Pressure Test Kit.

If air bubbles appear at the fitting when you lap it, the seal is no good. You’ll need to replace it.

How to fix a leaking brake line fitting

How to fix a leaking brake line fitting
How to fix a leaking brake line fitting

Method 1: Finding the Leak

The first step in repairing a brake fluid leak is to diagnose its location and severity. Once you have determined the location and severity of the leak, you will need to make the repair.

If you notice fluid leaking from your brake system, it is important to check the reservoir on the driver’s side near the rear of the engine compartment. If there is a low fluid level, then you may have a leak.

To verify a leak, check beneath the car for the presence of brake fluid. If the brake fluid is located near or at the wheel, it is likely that the leak is near or at that location.

Additionally, if there are any wet spots on nearby surfaces (such as grass), it’s possible that a leak has occurred and can be detected this way.

Place newspapers on the ground beneath the general location of the leak. Pump the brake pedal to force fluid out through the leak. Make sure that your car is not turned on for this process. Turning on the car would cause brake fluid to squirt out very quickly and make controlling a more difficult, if not impossible, task.

If you notice fluid dripping from your car’s brakes, it may be necessary to check the brake lines and calipers for leaks.

  • If the car has brake drums, there may be a leak in the wheel cylinder. You will have to remove the brake drum to check it.

Inspect the master cylinder for leaks. Depending on the model of car, it may be located in a different spot. You can find your car’s owner’s manual to locate the master cylinder’s location. If you no longer have a copy, then check online to find an original manual.

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To ensure that no fluid escapes from the master cylinder lid, make sure it is securely closed.

Method 2:Rebuilding Brake Calipers

 Remove the old caliper.

  • To replace a caliper, an automotive store or dealership may sell a rebuild kit. This kit includes all the necessary parts to rebuild the caliper.
  • To remove the brake bleeder bolt, use a flare-nut wrench. If needed, apply gentle tapping and penetrating oil to loosen the part without breaking it.
  • To disconnect the brake lines on a car, use a flare-nut wrench to loosen the nut and then pull away on the line. If they are cracked or worn, replace them before reassembling the calipers.
  • To remove the calipers, you will need to strip them of their pads, shims, springs and/or pins.
  • A piece of wood that is slightly thicker than both brake pads should be placed behind the piston in order to provide enough space for the caliper to move.
  • The air pressure in the cylinder should be released, causing the piston to pop out.

Replace the piston.

  • The new piston that came in the rebuild kit should be lubricated with brake fluid.
  • Piston installation is a simple process requiring moderate finger pressure. The piston should be inserted into the caliper until it rests on the wheel’s rotor.

Replace the caliper.

  • Change the outside dust seal.
  • Pads, shims, springs, and sliders or pins need all be replaced. Use the new components that came with your repair kit and toss the old ones.
  • Connect the steel and rubber brake lines once again.
  • The brake bleeder bolt should be replaced.
  • Check the brakes to ensure that they are no longer leaking.

Bleed all air from the brake system.

Method 3: Replacing a Wheel Cylinder

If your wheel cylinders are weeping brake fluid, it’s probably time to replace them. Replacing the wheel cylinder with an entirely new unit is much easier and only slightly more expensive than rebuilding the part.

Remove the wheel.

  • Remove the hubcap and the tire.
  • Raise the car using a jack so that the wheel is off of the ground.
  • Remove the lug nuts and the wheel.
  • Spray the steel brake line fitting with penetrating oil to loosen any existing rust.

Remove the brake drum.

  • Remove the rubber plug behind the backing plate to install or remove the battery.
  • To loosen the self-adjuster (star wheel) on the brake shoes, use a small flat head screwdriver to release the adjuster arm. If needed, turn the self-adjuster in the opposite direction to loosen it.
  • To loosen any rust that may have accumulated around the center piece of a drum, you may need to use a hammer.
  • Remove the drum.
  • If the brake shoes are covered in fluid, it is important to clean the area first with brake cleaner.

Loosen the steel brake line.

  • To prevent brake fluid from leaking out of the steel brake line, place a screw or bolt in one end of the vacuum hose.
  • To locate the steel brake line on the plate where it screws into the wheel cylinder, use a line wrench to loosen the fitting.
  • Remove the fitting.
  • To avoid a water leak, place the vacuum hose over the line.

Replace the wheel cylinder.

  • Locate the two bolts on the back of the backing plate that hold in place the wheel cylinder.
  • Use a socket wrench to loosen the bolts on the side of the engine.
  • The technician replaced the brake pads on the car.The technician replaced the brake pads on a vehicle.
  • Thread the steel brake line fitting into the new cylinder. Screw it in as far as you can by hand and then tighten with a wrench.
  • Bolts should be re-installed into the backing plate and screwed in to secure the new cylinder.

To bleed the air out of your brake system, follow method six.

Method 4: Replacing Steel Brake Lines and Hoses

If brake hoses are showing signs of wear and tear, such as cracking or becoming spongy or sticky, then they should be replaced. Brake lines that have patches of rust on them may also be in need of replacement due to the metal weakening from corrosion. If there are thin spots in the steel walls of the brake line, it may be time to replace them.

Remove the brake line from the fitting closest to the master cylinder. Use a flare nut wrench to unscrew it.

Remove the mounting bracket clips that hold the brake line in place. Then disconnect the brake line from the brake caliper using a line wrench.

Attach the new brake line to the caliper using bracket clips. Make sure the line is of equal length to the old one.

Attach the brake line to the fitting closest to the master cylinder using a line wrench. Tighten all connections.

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Brake system bleeding is a procedure used to clear air from the brake system. It is described in method six of the car’s owner’s manual.

Method 5: Replacing the Master Cylinder

Most modern brake systems have two circuits, with two wheels on each system. If one circuit fails, the brakes on the other system will still work. The master cylinder supplies pressure to both circuits. Replacing the master cylinder is usually cheaper than having an in-shop rebuild.

Locate the master cylinder and remove the cap to access the brake fluid.

Remove brake fluid from the master cylinder using a turkey baster. Pour discarded brake fluid into a plastic container.

Remove the brake lines by turning a wrench in a counterclockwise direction.

a socket wrench can be used to remove the mounting bolts.

To install the new master cylinder, secure mounting bolts and connect brake lines.

Connect the new master cylinder to the electrical connectors. Bleed all air from the brake system.

Method 6: Bleeding Air From the Brake System

Bleed all air and brake fluid from your system and replace it with new brake fluid. Brake pads will need to be replaced along with the new brake fluid.

Remove the cap on top of the master cylinder to release brake fluid.

To empty the master cylinder, use a turkey baster to draw all of the fluid from it. Pour any used fluid into plastic bottles and clean out any sediment with a lint-free rag.

Refilling the brake fluid reservoir with new fluid is a regular maintenance task you should complete. To find out which brake fluid is appropriate for your car, consult your owner’s manual or the underside of the reservoir cap.

To bleed the brakes on your car, loosen the bleeder screw located on the caliper or wheel cylinder at the right rear of your vehicle. Bleed each brake one at a time to avoid drawing air into the system.

Attach a vinyl hose to the bleeder screw. Place the opposite end of the vinyl hose into a clear plastic bottle.

Please instruct your assistant to press the brake pedal as far down as it will go.

After all of the air bubbles are released, tighten the front right brake fluid bleeder screw.

Please have the assistant pump the brake pedal until it becomes hard and builds up pressure. This will draw fluid into the master cylinder. The fluid should squirt into the bottle each time he/she pumps the brakes. Do this until new, fresh brake fluid starts coming out.

  • The master cylinder should be refilled with fluid as needed to prevent it from becoming more than half-full.

Please have your assistant press the brake pedal again to tighten the brake fluid bleeder screw and remove the hose.

  • Bleeding the brakes on a car is an important step in ensuring safety. To bleed the brakes, first remove one wheel. Next, use a funnel to fill the brake bleeder valve with brake fluid and slowly release it while watching the gauge. Repeat this process until all four wheels have been bled.

Top off the master cylinder with brake fluid.

In order to test the brakes, it is necessary to top off the master cylinder with brake fluid.

F.A.Q about “how to fix a leaking brake line fitting”

Why is my brake line fitting leaking?

Brake lines can leak when there is a poor connection between the seat of the fitting and the brake line. This type of leak is known as a weep, and it is the result of a tiny imperfection in the flare that occurs while flaring the tube.

How do you stop a flare fitting from leaking?

To prevent a leak at the joint between the flare and cone, loosen and tighten the flare nut several times to the torque specifications.

Can I use Teflon tape on brake fittings?

Brakes need to operate under high pressure and cannot rely on anything to stop a leak. Teflon tape can damage the system if it is used on the brake lines.

Can I crimp a leaking brake line?

If the leak is on a branch leading to a brake line, you can use crimping tools to create a seal. This will stop the fluid from leaking and give you full pressure in your other lines.

Is there a sealant for brake lines?

If you’re using your brake system correctly and don’t need any lubricants or sealers, you can avoid contaminating the system with oil or other fluids by using clean brake fluid.

Can you patch a brake line with rubber hose?

Using a regular rubber line with a brake system is not recommended due to the high pressure exerted on the line by the brakes. Additionally, brake fluid can damage rubber hoses over time.

How do you fix a leaking fitting?

How tight should brake line fittings be?

To tighten a nut, start by tightening it finger-tight and gradually increase the pressure until you feel it draw down tight. Then tighten by 1/6 turn. Do not over-tighten.

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What do you put on brake line threads?

Staying away from Teflon tape on any brake/fuel system is always a good idea, as any good pipe thread sealant (paste) with Teflon or PTFE will do the job just as well.

How much does it cost to fix a leaky brake line?

Average Brake Fluid Leak Repair Cost
Type of Leak Repair Cost
Repair Parts = $100-$200 Labor = $80-$140
Replace Parts = $200-$300 Labor = $40-$80
Brake Line Leak
Repair $100-$200

Can you solder a hole in a brake line?

If you’re looking to solder brakeline, you need the right flux and silver solder. Use a MAP gas torch to ensure a good connection.

How do you temporarily fix a brake line?

How do you temporarily plug a brake line?

Should you use Loctite on brake lines?

Do not use sealants or lubricants on brake lines; only brake fluid should be used when assembling the brake system. If the flare/cone seal of the brake fittings does not provide a seal, then the parts must be replaced. There are no safe methods to fix these parts if they do not meet this standard.

What sealant is brake fluid resistant?

Seal-All is a household product that can be used on metal, glass, wood and leather. It is the only product I have ever used that will withstand exposure to gasoline or brake fluid (DOT 3 and DOT 4).

How do you find a leak in a brake line?

If you notice any wet or dry fluid streaks on the inside of your car’s wheels, rust spots along the brake line lines, or any drips, you may have a brake line leak.

Can you splice rubber brake line?

Some people believe that it is illegal to make a new section of brake line and splice it into a non-rusted section of your old brake, but this is not actually the case. You must use automotive grade SAE double/inverted flare, SAE “bubble” flare and DIN Single Mushroom flare unions and fittings in order to avoid any problems.

Can I use hydraulic hose for brake line?

Do not use hydraulic fluid to apply the brakes because it will deteriorate the hose and make it gummy and collapse.

Can I replace hard brake lines with braided?

Replacing a hard brake line with a braided one will result in a softer pedal. This is due to the fact that the braided line can expand where the original steel line cannot.

Can I use Flex Seal on a leaky pipe?

A leaky pipe can be fixed with Flex Seal Tape or Liquid. You’ll be hard pressed to find a repair that can’t be fixed with a Flex Seal product.

How do you temporarily fix a leaky pipe?

Epoxy putty or pipe putty can be used as a temporary fix to a leaky pipe. This type of putty hardens at room temperature and seals the hole or crack.

Can you over tighten a flare fitting?

Fourth, do not over tighten the flare fitting as this can cause leaks. Daikin offers preset torque wrenches that will allow you to properly tighten the flare fitting without over tightening them. Always use a backup wrench when tightening any flare fitting.

What does a flare fitting look like?

How do you seal flare fittings?

How do you fix a brake line?

How much is a brake line kit?

You should expect to pay around $150 to $200 for a steel brake line repair. The cost of just the parts is usually between $30 and $50, while the rest of the cost is typically labor involved.

Will brakes still work without fluid?

Brake fluid is a liquid that transfers the pressure from your brake pedal to the brakes. Without it, your brakes would not work.

How do you weld a brake line?

What is the PSI on brake lines?

Metal brake lines burst around 15,000 psi. Brake line pressures vary depending on the type of brakes, but are typically around 900–1,000psi (69 bar) with manual brakes and 1,400-pluspsi (96 bar) with power-assisted brakes.

How do you connect two brake lines together?

How To Fix Leaking Brake lines

How to | Prevent a Brake Line Fitting from Leaking


If you are having any problems with your brake line, please do not hesitate to call us. We would be happy to help you out. Thank you for reading.

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