How to replace a rusted brake line— YOURSELF
Brake lines rust out quickly if you live in the salt belt. Having a shop replace your rusty brake lines can easily cost upwards of $1,000 or more because it’s a labor-intensive job. In some cases, the shop can buy pre-bent stainless steel brake line kits, but they’re not as easy to install as it sounds. That’s because those kits replicate the path the factory took when running the lines, and sometimes requires removing components.
For example, the carmaker may have run the rear brake line over the top of the fuel tank. The pre-bent replacement kit will duplicate that route, which means the shop will have to drain and remove the fuel tank. But keep in mind, the carmaker did that to save assembly time. As long as the new brake line is run in a safe location, it really doesn’t have to follow the exact same path. That’s one reason why pre-bent kits may not be the way to go.
If you have mechanical knowledge and some tools, a floor jack, and jack stands and are willing to buy or rent the proper brake flaring and bending tools, you can do the entire job yourself for around $250. I’ll show you the step-by-step way to replace rusty brake lines.
Here’s what you’ll need to replace rusted brake lines yourself:
Here are the brake line supplies you’ll need
Buy the best flaring tool out there
The S.U.R. & R. hydraulic flaring tool is the best in the business. It’s idiot-proof and worth every penny. It can even make the difference between a flare that works or one that leaks and causes you to replace a section you just bent and replaced. The kit costs about $235 online. When you’re done with the job, just post the kit on eBay and sell it for about $190 to recoup the majority of your investment
Forget about cheap brake line tubing benders
Here are the two brands I recommend.
Step 1 to replace rusted brake lines: Disconnect the brake line at the ABS modulator or the master cylinder
If you start the job by disconnecting the line at the leak site or the caliper/wheel cylinder, the line will continue to drip and drain the master cylinder. That’ll require a bench bleed when you’re done, which is a complete waste of time. If you disconnect the line under the hood and plug it, you won’t have to perform a master cylinder bench bleed.
Step 2: Disconnect the brake line where it attaches to the brake hose
I’ll show you how to replace a rusted brake line that connects to the rubber brake hose. Those fittings are usually completely rusted to the brass fitting on the brake hose. If your leak is in a horizontal line, skip to the next step.
If the brake line fitting won’t budge
Rust is like glue, so it seals the threads and prevents the rust penetrant from wicking into the threads to dissolve rust, lubricate and allow the fitting to move. Vibration breaks up the rust and allows the rust penetrant to seep into the threads.
WARNING: The fitting will be rusted. If you don’t follow my instructions, you’ll strip the fitting and possibly damage the brake hose. This requires a bit of patience and finesse to remove
However, if your fitting still won’t unscrew from the rubber brake line, you’ll have to but the steel line and splice in a new section, along with a new rubber brake hose.
Use the mini-tubing cutter or long-handled side cutters and cut the tubing. Then try using a deep socket to remove the fitting. If that twists the brass fitting on the brake hose, you’ll have to replace the complete brake hose.
Step 3: Cut out the rusted brake line section
Follow the rusted brake line back until you reach a good section. Use the mini tubing cutter to cut the line. This is where you’ll splice in a new line.
Step 4: Clean and flare the freshly cut line
Clean off any dirt and debris from the freshly cut line. Slide on a new flare nut to fit the coupler union. Load the line into the S.U.R. & R. flaring tool and perform a two-step double lap flare.
Insert the flare punch into the tool and squeeze the trigger. That will complete the flare.
Step 5: Bend the replacement line
Step 6: Connect the new brake line section to the coupler union
Step 7: Reconnect the brake line at the ABS modulator or master cylinder
Refill the master cylinder. Then bleed the brake line with a handheld vacuum pump.
©, 2020 Rick Muscoplat, Alex Steil