Brake Hoses, Lines, and Fittings

What are brake hoses, lines, and fittings and where are they located?

As you know, whenever you need your vehicle to slow down, you simply have to press the brake pedal and your car gradually comes to a stop. You’re probably also aware that, behind the scenes, it’s not that simple. Each time you press the pedal you’re activating a pushrod that passes through the brake booster (also known as the vacuum servo) which amplifies the amount of pressure applied to the pedal. Without the booster, you’d need Hulk Hogan legs for those close calls. The pushrod then pushes the pistons in the master cylinder, creating the hydraulic pressure needed to send the brake fluid through the brake lines to activate the caliper pistons or drum brakes and stop the vehicle. Obviously, without the brake lines, tubes, and fittings, your brake fluid has nowhere to go.

This type of hydraulic braking is the most common braking system in cars on the road today. You can find your brake lines by looking under the hood and under the car. The lines will usually begin at the master cylinder near the engine and then separate and end at each wheel. Each will be connected by a brass or steel fitting. The lines can be made from all sorts of materials, but many are made from steel, stainless steel, brass, copper-nickel, rubber, etc., some of which can come braided. Prior to WWII, most vehicles featured copper/brass type brake lines, but today many feature a type of double wrapped steel and some may include both rubber and steel brake lines.

How do I know if my brake hoses, lines,  and fittings need to be replaced?

Since making the change to steel, brake lines have done a pretty good job of staying intact, but, unfortunately, they’re not fool-proof and can have their flaws. You never want your brake lines to be cracked, split, flaked, or corroded in anyway. Signs of rust can be a strong indicator that a replacement is needed, since rust can also contaminate the fluid, which can lead to further damage to the seals in the brake caliper and master cylinder. A good way to stay on top of this is to inspect the brake lines and fittings every so often, for example when you are change or rotate your tires.

You’ll also want to inspect the mountings (especially if you live in colder, northeastern states) since they can be prone to trapping salt and water, or, even worse, they may have fallen off completely. It’s imperative that you replace any mountings if they’re missing to avoid putting more stress on your lines; the car’s vibration of sagging lines can lead to looseness, splitting, and leaking.

If you have rubber lines, check for dryness and sturdiness, as any lines that are sticky or soft need to be replaced. Staining may also be a sign of interior deterioration. Since rubber lines and tubes have a tendency to hang, there is always a chance that they can latch onto a part of the road or an object thrown up from the tire and tear. Regular inspection of all clips and mounts can prevent this from happening.

If you have any of these issues and your lines aren’t leaking, chalk it up to luck and get your brakes checked immediately. Under no circumstance should you drive with any faulty component in your braking system, as having shoddy brakes in the middle of traffic is going to be problematic for you and other drivers around you. If you’re ever suspicious that a particular section of your lines is leaking, you can enlist the help of an assistant and ask your helper to pump the brakes while you inspect the spot for leakage.

Can I replace the brake hoses, lines,  and fittings myself?

Yes, the brake lines can be replaced by a do-it-yourselfer, but the degree of difficulty and duration of the job can vary from vehicle to vehicle. Before beginning, check your brake fluid level and make sure the fluid is at or near the “full” line. You don’t want to run out of fluid at any point during the repair. The tools you’ll need typically include a set of wrenches, a tube cutter, rust penetrant, flare nut wrench, line wrench, brake bleeder wrench, drip pan, tube bender, double flare kit, and brake fluid. If your lines are old and rusted or damaged throughout, it’s probably a good idea to swap out the entire line. Otherwise, replacing certain sections is a viable option. Also, some brake line setups may be more troublesome than others and will require a lot more patience, but the good part is that brake lines don’t need to be reinstalled in the original position you found them in, granted that they’ll fit in the new space you want to put them in.

After you’ve scanned and searched the lines for any leakage or wear and tear, you’ll want to remove the tire that works directly with the faulty brake line. Then spray the caliper or brake cylinder with rust penetrant where it meets the brake line. After that’s been soaked for a bit you can loosen the line from the caliper or cylinder. Have a drain pan ready to catch any leaking fluid. Then loosen and remove the lines from their fittings and clips with a flare nut or line wrench. Cap off any separated lines that leak fluid, then remove the line from any mountings or clips.

To prepare the new line, measure and cut the material to the appropriate length with a tube cutter and clean out the ends. If you need to reshape any part of the brake line, plan out the dimensions and curve the line accordingly by using a tubing bender. To double flare the lines, insert the fittings onto the line first with the thread facing the end to be flared. Insert the end into the flaring bar and tighten it. Then place the adaptor into the brake line. Insert the flare into the line and turn it to flare the line.

When you’re ready, line it up into position and splice the new line to the old line with new fittings. When you’ve completed the job, double check the brake fluid level in the master cylinder and add any brake fluid as needed. Then bleed the brakes. This is done best with the help of an assistant. First, find and remove the bleeder valve from the caliper or brake cylinder. Then place a piece of hose on the end of the bleeder valve screw and place the other end into a drain pan. Ask your assistant to pump the brakes. Then, loosen the fitting until fluid drips out. Air bubbles in the pan will indicate that air is being let out of the lines. Then tighten the fitting and ask your assistant to release the brakes. Do this until all air bubbles have been removed. Then replace any missing brake fluid.

Once the process has been completed, reattach the wheel and pump the brakes a few times. Then turn the vehicle on and perform a stopping test from 5 mph and 10 mph. Press the brakes fully a few times, and if they feel softer than usual bleed the brakes again.