How to fix a broken brake line

I just found out my brake line is leaking, and the towing company quoted me over $100 to bring it to a mechanic 18 miles away. I can’t afford that right now. How do I fix a brake line quick and safe, just temporarily so I can get to the mechanic?

Matt Terzi

You did the right thing to stop driving until you can figure out what to do next. Driving with leaky brake lines is very, very dangerous.

We don’t want to recommend this as a method to fix a brake line quickly, but it is a temporary, short-term solution that can get you to the mechanic as long as that’s your only stop and it isn’t too far away. Attempt this at your own risk, and please drive carefully if you try it!

You’re going to need an adhesive, like tape or rubber cement, to patch the leak in the brake line. Most auto parts stores carry a special hydraulic system or brake system patching glue that can help. Just be careful none of this gets into the brake line, as it can cause serious damage to other components.

Rescue Tape is a very popular product a lot of DIY car repair fans keep in their glove box or trunk. You can use this for a temporary, quick brake line fix that will get you to the mechanic. Some drivers have also used duct tape or electrical tape, with mixed results.

The most important thing to remember here is that you need to get to the mechanic safely and immediately, and drive like someone’s great-great-grandparents are surfing on the hood. Drive slowly, brake gently, and don’t make any unnecessary stops along the way.

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When you have trouble keeping your car's brake fluid levels up where they need to be, there is a good chance that one or more of the brake lines has developed a leak and is allowing hydraulic brake fluid to leak out of the system. When this happens, the brakes will initially feel spongy, they may stop working altogether. Failing brakes indicate a serious situation that needs to be dealt with immediately.

While a leak is possible anywhere along the hydraulic brake lines running to the master cylinder to the individual brake piston housing on the wheels, it is most common at the flexible portion of the lines that run from the brake's piston housing to the rigid the rigid piping that continues on to the master cylinder. Because these flex tubes are exposed to the road and move with the wheels move as the car is steered, it's not uncommon for these lines to get brittle and develop cracks.

This article will discuss the replacement of the flex hose portion of the brake line that joins directly to the brake's piston housing. Make sure to buy a replacement brake hose that matches your car's specifications. Most mechanics will replace the brakes lines on both wheels at the same time since if one line is bad, it's likely the other one may go bad soon.

Brake fluid
New flexible brake lines
Screwdriver (if needed)
Open-end wrenches
Rags
Jack stands
Tire lug wrench

Use two wrenches to loosen the brake line. photo by matt wright, 2007

Place your car on jack stands or jack up the car, then remove the wheel.
Identify the rubber or steel mesh flex line that runs from the brake unit's piston housing to the rigid metal portion of the brake line.
If there is a retainer clip on the hose at the fitting locations, remove it with a screwdriver.
Normally, the connection points each consist of two halves joined with hex-shaped fittings. Position a rag beneath the fitting to catch the brake fluid as it drains out.
Use one open-end wrench on each half of the fitting, and twist them in opposite directions to free the fitting.
If the hose is anchored at some point in the center to a strut of other fixed point, detach this connection.

The fittings on the new brake line. photo by Matt Wright, 2007

Installing the new brake line is really just a matter of reversing the process used for removal.

If there is a retainer clip on the new hose, attach this to the piston fitting.
Carefully hand thread the connection together, by hand.
Once it's hand tight, use two open-end wrenches to tighten the fitting securely.
If there is a fixed mounting bracket that secures the hose to a strut or other fixed point, make this attachment to finish the installation.

New brake line installed. photo by Matt Wright, 2007

With the new brake line installed, you'll need to add brake fluid to the system and bleed the brakes of air that is in the lines.