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Brake Hose Inspection Tips to Spot the Problem Before It’s Too Late

There is no recommended replacement interval for brake hoses. That’s because brake hose conditions will differ depending on the vehicle, driver, and environment. Inspection is the only way to spot a problem before a brake failure.

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There is no recommended replacement interval for brake hoses. That’s because brake hose conditions will differ depending on the vehicle, driver, and environment. Inspection is the only way to spot a problem before a brake failure.

Brake hoses should be inspected visually and with your hands. It might be helpful to have someone pump the brake pedal to spot a defective brake hose. Failure typically occurs at the ends of the hose. This is the place where a hose flexes due to suspension/steering movement. This is also where it is exposed to damage from debris and heat from the brakes.

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You’ll need to replace the hose if any of the following signs are present:

Cracks – Try flexing the hose to expose cracks. No matter how small, shallow, or random the crack, the hose should be replaced.

Blisters or bubbles – Having someone pump the pedal will help spot this type of damage. The hose should not change shape. If even the smallest deformation is detected, replace the hose.

Leaks or stains – Brake hoses should never leak. A leak equates to lost braking force and becomes an entry point for air and moisture. Air in the fluid is bad because air is compressible. This increases the amount of pedal travel that’s necessary to apply the brakes, and may increase it to the point where the pedal hits the floor before the brakes apply.

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Physical damage – Run your fingers along the length of the hose. A brake hose should be free of any irregularities.

Corrosion on the fitting – Most fittings are plated to prevent corrosion. If this plating wears away, corrosion can occur at an accelerated rate.

Corrosion on brackets or mounting hardware – Rust on the brackets can constrict a hose.

The Future of the Hose

What does the future hold for brake hoses? With efficiency of the engine becoming more important, the performance of the vacuum brake booster is coming into question. Engineers see the vacuum brake booster as a vacuum leak that can make the engine run rich or lean.

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Without a booster, the transfer of force from the pedal to the caliper has to become more efficient. This could mean even stiffer and smaller-diameter brake hoses in the future.

Brake Hose Service Recommendations

1. If the brakes have undergone extreme thermal shock, replace the hose.

2. Always make sure the angle of the banjo fitting is correct. 

3. Use a torque wrench on banjo fittings.

4. Use new copper washers.

5. When a caliper is sold, also recommend a new brake hose.

6. Never let a caliper dangle by the hose.

7. If you plan to clamp a hose to push the piston back or for a diagnostic procedure, clamp the hose in the middle, not near the ends or where it curves.

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8. If a replacement hose isn’t marked with the proper DOT and/or SAE-mandated marking that includes the date, manufacturer name and the letters “DOT,” send it back.

9. If a hose on a vehicle does not have a torque stripe or other markings, it might be the original hose. Inspect it more carefully for damage.

10. Don’t twist the hose. All replacement brake lines have a “torque stripe” or labeling information that should be straight when the hose is installed.

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What Do the DOT Regulations Really Mean?

The brake hose is among the most government-regulated components on a vehicle. Any company making brake assemblies must be registered with the Department of Transportation (DOT), and all aftermarket bulk hoses, fittings and complete hoses must conform to FMVSS 106 and SAE J1401. These tests are demanding and often exceed what a vehicle experiences in the real world.

In a nutshell, the DOT standard says the brake hose must be flexible throughout a wide range of temperatures, while also having a predictable expansion rate so the pedal feel and ABS response are the same in winter and summer. It also specifies that the brake hose must be able to bend and twist at certain angles without collapsing, kinking, or bursting.

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While FMVSS 106 and SAE J1401 do not specify construction or materials, they do outline a test procedure that completed hoses must pass.

These tests and standards include:

Markings: Each hydraulic brake hose, except for the originals, must have at least two clearly identifiable stripes of at least 1/16-inch in width, placed on opposite sides of the brake hose parallel to its longitudinal axis. These are called “torque stripes.” One stripe may be interrupted by the information printed on the hose. They are designed to prevent twisting during assembly and installation.

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Whip testing: Brake hoses are continuously bent on a flexing machine for 35 hours at pressure.

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