Brake hoses and brake lines: rust, leaks and the APK (MOT)

Between the brake pedal and the brakes at the wheels is a closed system of lines and hoses full of brake fluid. If something goes wrong there, the car brakes poorly or not at all. This article explains what brake hoses and brake lines do, why they fail, how you recognise a leak, what the inspector fails at the APK (MOT), the compulsory Dutch vehicle inspection, and how we replace them.

By the team at Autobedrijf Willemsbrug, RDW-approved APK (MOT) test station since 1979 · Updated 6 November 2026

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The short answer

Brake lines are rigid metal pipes that carry the brake fluid from the master cylinder to the wheels. Brake hoses are the flexible rubber sections at the wheels that move with the suspension and the steering. Lines fail mainly through rust, hoses through ageing, chafing and internal blockage. You notice a leak by a dropping brake fluid level, a soft or sinking pedal and a wet patch at a wheel. At the APK, a brake line with pitting corrosion or a brake hose with visible reinforcement is a fail. At Autobedrijf Willemsbrug in Rotterdam we replace hoses and lines, bleed the system and tell you the cost in advance.

Brake service at Autobedrijf Willemsbrug: brake pads, discs, fluid, calipers, hoses and the handbrake or electric parking brake, for all makes, including hybrid and electric cars, vans and motorhomes up to 3,500 kg. We first measure what is worn, replace only that and show you the old parts. We tell you the price in advance based on your registration number, and we only do extra work with your approval. Call +31 10 479 00 00 or drop by. You bring the car and we call you when it is ready. A loan bike is free while one is available. Saturdays too. Our team speaks English. More about our brake service

What are brake hoses and brake lines?

Brake lines and brake hoses together carry the pressure from the brake pedal to the four wheels. When you press the pedal, the master cylinder builds up pressure in the brake fluid. That pressure travels through the lines and hoses to the brake calipers or wheel cylinders, which press the brake pads or brake shoes. Fluid cannot be compressed, so every movement of the pedal arrives directly at the brakes, as long as the system is sealed and contains no air.

Brake line (brake pipe) Brake hose
Material Rigid metal pipe, usually steel with a protective coating, often replaced with a copper-nickel alloy Flexible rubber hose with a fabric reinforcement, sometimes with a steel braid
Where Under the car, along the floor and the axles, from the master cylinder and the ABS unit to the wheels The last section at each wheel, between the fixed line and the brake caliper or wheel cylinder
Why Strong, cheap and withstands high pressure Has to move with the suspension and, at the front, with the steering
Fails through Rust from the outside, mainly from road salt and moisture, and damage from stone chips Ageing of the rubber, chafing, kinks and internal blockage
APK fail Pitting corrosion after removing surface rust, leaks Visible reinforcement, serious deformation, chafing against other parts, leaks

Source for the APK requirements: RDW APK manual passenger cars, article 5.2.31 of the Dutch vehicle regulations, consulted 6 November 2026.

Why do brake hoses and brake lines fail?

Brake lines fail almost only through rust. They run under the car, where water, mud and road salt splash against them. The protective coating keeps that out for years, but where the line sits in a clip, runs over the rear axle or where stone chips have damaged the coating, moisture stays behind. There rust eats pits into the steel, until the wall gives way under high brake pressure. That often happens at the moment you brake hard, which is when you need the brakes most.

Brake hoses fail through age and movement. The rubber dries out, hardens and cracks. Brake manufacturer Ferodo advises checking hoses regularly for chafing, cuts, general deterioration and leaks. A hose that rubs against a spring or a tyre wears through from the outside. A kinked or twisted hose weakens at the kink. According to Ferodo, a poor hose can also swell under pressure, which makes the pedal respond badly.

Old brake fluid makes it worse. The fluid absorbs moisture over the years. That moisture attacks the metal from the inside, in the lines, the calipers and the ABS unit. That is why changing the brake fluid according to the manufacturer’s schedule, usually every two years, is part of looking after the lines too. Read more in our article on changing brake fluid.

How do you recognise a leaking or worn brake hose or brake line?

You notice a leak in the brake system by the pedal, by the brake fluid level and by a wet patch. The brake system is sealed, so a dropping level has a cause. The ANWB, the Dutch motoring organisation, writes that an incorrect level can point to a leak and that a warning light comes on when there is too little brake fluid. These are the signs:

  • The brake pedal feels soft or spongy or has to be pressed further than you are used to. The ANWB lists this as a sign of a problem in the hydraulic system.
  • The pedal slowly sinks while you hold it down, for example at a traffic light.
  • The red brake warning light is on. According to the ANWB this can point to too little brake fluid.
  • The level in the reservoir drops and keeps needing a top-up.
  • A damp or dirty patch on the inside of a wheel, on the brake caliper or on the line under the car.
  • A drip or a stain under the car near a wheel or under the engine bay. What each colour means is explained in our article on fluid under the car.
What you notice Can you keep driving?
Pedal sinks away or suddenly feels soft, brake warning light is on, brake fluid at a wheel or under the car No. Do not drive on. Park the car safely and call us. A leak gets bigger with every brake application.
Level slightly below the maximum mark, pedal feels normal, no wet patches Yes. A slightly lower level can also come from wear of the brake pads. Have it checked at the next opportunity.

Decision rule of our workshop. Not sure? Call us and we will schedule a short brake check. If nothing needs doing, we tell you that too.

A leak is not the only cause of a soft pedal. Air in the system, old brake fluid or a worn master cylinder give the same feeling. For a faulty master cylinder the ANWB lists a soft or spongy brake pedal, a pedal that slowly sinks and sometimes a leak or a warning light. All the causes are listed in our article on a soft or spongy brake pedal.

Internally blocked brake hose: the caliper does not release

A brake hose can close up on the inside without anything being visible from the outside. After years the inner layer of the rubber comes loose or swells. It forms a valve: when you brake, the pressure still gets through, but when you release the pedal the fluid cannot flow back. The brake caliper then stays applied. The wheel gets hot, you smell burning, the car pulls to one side and the brake pads on that side wear out in a short time.

This looks like a seized brake caliper and is often confused with it. The mechanic tells the difference by opening the bleed nipple on the caliper while the wheel is locked. If the caliper then frees up, the pressure was trapped in the hose. If it does not, the piston or a guide pin of the caliper is seized. Read more in our article on a seized brake caliper.

A hot wheel after a drive, a burning smell or a car that pulls to one side when braking: do not drive on, call us. A brake that keeps dragging gets so hot that the brake fluid can boil and the brake disc can warp.

What does the APK require of brake lines and brake hoses?

The inspector checks lines and hoses visually, without taking anything apart, and carries out a pressure test when in doubt. The APK manual of the RDW, the Dutch vehicle authority (article 5.2.31 of the Dutch vehicle regulations), requires that the parts of the braking system are properly secured, not seriously affected by corrosion, not damaged, cracked or broken and show no internal or external leaks. For lines and hoses there are additional requirements:

  • Brake lines and pitting corrosion: a brake line may not be so affected by corrosion that pitting remains visible after the surface rust has been removed. Surface rust on its own is therefore not a fail, pits in the metal are. A seriously corroded brake hose fitting is also a fail.
  • Brake hoses: a brake hose may not be seriously deformed, may not chafe against other parts of the vehicle and may not have damage that exposes the reinforcement. Sharp kinks and heavy twisting are not allowed. Surface cracks that do not yet expose the fabric are not a fail and not an advisory either.
  • Leaks and the pressure test: when in doubt about the seal, the inspector slowly presses the pedal with at most 700 N and holds it for about 10 seconds. The pedal may not sink.
  • Brake fluid reservoir (article 5.2.32): the level may not be below the minimum mark and the filler opening must be closed with a proper cap. The quality of the fluid is not measured at the APK.

The inspector checks the hoses with the wheels turned fully to the left and to the right, so he can see whether a hose touches anything or is pulled tight. If we repair the items that failed, we will also arrange the retest. We will tell you the cost of the repairs and the retest in advance. What else the RDW requires is explained in our article on an APK failure on the brakes.

How we replace brake hoses and brake lines in Rotterdam

We replace only the part that is faulty, bleed the brake system and then test on the brake tester. We do not repair a rusted brake line with a piece of hose or a clamp. We make the affected section new, with the correct fittings, in the shape of the original. This is how it goes in our workshop:

  1. On the lift, the mechanic follows every line and hose from the master cylinder to the wheels and scrapes away surface rust to see whether there is pitting underneath.
  2. He assesses the hoses for cracks, chafe marks, swelling and, if a brake is dragging, for internal blockage.
  3. We tell you in advance what needs replacing and what it costs, based on your registration number. We only work with your approval.
  4. He replaces the hose or the section of line and secures the line in its clips again, so it cannot vibrate or chafe.
  5. He then bleeds the brake system in the manufacturer’s sequence and changes the brake fluid if it is due. On some cars diagnostic equipment is needed for the ABS unit.
  6. Finally he checks all fittings for leaks under pressure, tests the car on the brake tester and takes a short test drive.

If a brake hose is worn, we often advise replacing the hose on the other side of the same axle as well, because it is the same age. We tell you that in advance and you decide. We check the lines and hoses at every service and APK. Everything about our brake service, and what is included in the price, is on the page brake replacement in Rotterdam.

Frequently asked questions

Can I still drive with a leaking brake line?

No. A leak gets bigger with every brake application and can take away the braking on that part of the brake system in one go. Park the car safely and call us. If the car can no longer be driven safely, have it brought to us. How that works is on our page about a car breakdown in Rotterdam.

How long do brake hoses last?

There is no fixed number of years or kilometres. Rubber ages with time, heat and ozone. Ferodo advises checking the hoses regularly for chafing, cuts, deterioration and leaks. We do that at every service and APK.

Is rust on a brake line a fail at the APK?

No, surface rust is not. The RDW APK manual fails a brake line if pitting corrosion remains visible after the surface rust has been removed. So the inspector scrapes the rust away and looks for pits in the metal.

Can a brake line be repaired or does the whole line have to be replaced?

Usually we replace the affected section and join it to the good part with new fittings. Replacing the whole line is needed when the rust runs along its full length. A piece of hose or a clamp over a leak is not a repair. We tell you in advance what your car needs.

Why does my car pull to one side when braking if a brake hose is faulty?

Because an internally blocked hose holds the pressure on one side or blocks it. If that side brakes harder or keeps dragging, the car pulls to one side. At the APK the difference in braking force between left and right on one axle may not be more than 30 percent. We measure that on the brake tester.

Does the brake fluid have to be changed when a hose or line has been replaced?

No, not in every case. The system is bled in any case, which replaces part of the fluid. If the brake fluid is older than the manufacturer’s schedule allows, usually two years, we change all of it in one go. That saves doing the job twice and we tell you the cost in advance.

How do I know whether the wet patch at my wheel is brake fluid?

Brake fluid is clear to yellow-brown, thinner than oil and feels slightly oily. If the patch is on the inside of the wheel or near a line, and the level in the reservoir is dropping, it is almost certainly brake fluid. Do not drive on, call us. Condensation from the air conditioning is clear and dries quickly.

Brake line or brake hose checked?

Call +31 10 479 00 00 with your registration number. We find the leak or the rust, replace only what is faulty and tell you one price in advance.

You will find us at Boterdiep 11 in Rotterdam-IJsselmonde, close to Stadion Feijenoord (De Kuip). We work by appointment. For a quick question or check you can walk in without an appointment.

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