Standard Practice for Replacing Brake Lines

Alrighty, a week ago I lost all breaking pressure suddenly while driving. I wasn’t far from home and got the rest of the way back slowly and used the emergency brake to stop. I had my car towed and taken to a repair shop. All they told me was that the rear brake line was out and they were replacing it. I was charged on my invoice for a brake line, brake line nut, and brake fluid.

I suddenly lost pressure again while driving. It happened fast. It was fine one minute then a minute later no brake pressure. Pumping the brake didn’t return the pressure. I was lucky to be able to pull over. Called the same towing/repair place (only one in my town) to come get it. When the towing guys got there I popped my hood and had them show me where the brake fluid was. It was pretty empty. The other guy hit the pedal and commented that it must be spewing fluid somewhere.

I asked them how this same thing I got fixed happen again in a week. If one brake line was bad how come the others weren’t checked. The response I got was as follows:
#1- Brake lines corrode from the inside out and you can’t tell by looking at it when it’s bad. All brakes will get bad eventually because brake fluid is acidic.
(this seems problematic from a logical safety standpoint.)
#2- when you replace one brake line the others can go because of pressure change and imbalance.
(So then why isn’t it standard procedure to replace all lines at once?)

I also read elsewhere that if any brake lines show signs of decay its a good idea to replace all brake hoses since they deteriorate at the same rate inside and out and that’s a good tell tell sign.

So am i getting dicked around by shoddy mechanics? What is the standard when it comes to brake line replacement?

Brake lines can rot from the inside if the fluid is not changed on a regular basis as it should be or rust from the outside due to road salt, age, etc.

The reason for hesitancy about replacing everything at once is that mechanics are quite frequently accused of gouging and piling on.
For every customer who agrees with the notion of one bad/they’re all bad there are many more who will accuse the shop of gouging by recommending they all be replaced.

There is no standard. My opinion is that if one line is in bad shape the customer should be advised they all need replacement and that puts the ball on the customer’s side of the court.

This then leads to the point of brake lines being badly corroded to the point of failure and other parts which are likely on the edge. That would include master cylinders, wheel cylinders, and brake calipers.
Tell the customer they need all the lines, MC, WCs, and calipers and watch the accusations fly…

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It would help if we knew what you were driving. Our brake lines around here always rust from the outside in. Unless your car is very, very old I cannot imagine a brake line rusting from the inside.

It sounds to me that your shop will come up with any story that sounds good to convince you that nothing is their fault.

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I suppose when it comes to brakes and the safety involved I’d rather a mechanic be upfront about everything. If there’s a logical reason to replace all that then I will and avoid paying for it latter. I just wish it was mentioned that there was more that might have needed repaired. I just got this car used from a reputable dealer 6 months ago.

it’s only a 2002 Haundai Sonata without even 100,000 miles yet. I am in the northeast though

Each brake line “lives” in a different environment. You were the victim of bad luck, not a shoddy mechanic IMHO.

At 13 years old in the northeast you can expect brake lines to start rusting out. It’s much more a time issue than a mileage issue.

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The better question is, “what is the standard for brake fluid replacement?” Most car makers recommend replacing the brake fluid every 2-3 years. Most owners ignore this recommendation, and as a result, brake fluid slowly absorbs moisture from the air and causes corrosion inside the brake lines. If your shop tested your brake fluid they would likely find it contains a high percentage of water from not being changed in the life of the car, I’d guess.

Your mechanic is not the problem. He was being cautious in not trying to replace too many parts and being accused of gouging.

The problem is you and/or previous owners not changing the brake fluid every 2-3 years as recommended by the manufacturer (check your owners manual).

Since I haven’t had the car for a year I know it’s probably just dumb luck. I suppose I assumed too much when I thought the dealership handled everything about making the car up to snuff for passing the PA inspection and sale. I just wish the mechanic was honest and up front about what could happen and what might need done and let me decide as someone else pointed out earlier. It’s honest and avoids gouge accusations

Brake lines are mostly metal, with a section of rubber hose at each wheel. The rubber section is needed to allow for the up and down movement of the suspension. Most often it is a rubber section that fails. The metal tube section last a lot longer. Was you brake line failure at a fitting? In a rubber section? Or, in the metal tubing?

If one of the rubber sections failed, then other rubber sections are likely in similar bad shape. The metal lines hold up OK if you change the brake fluid every 3 to 4 years. If you never changed the brake fluid after 13 years the fluid likely has become polluted with water, and that water can rust the metal lines from the inside out.

More info about the specifics of what failed and where would get a better answer about what to do now.

Those are very good questions for me to ask the mechanic. As I said the ONLY thing they told me was my rear break line was out the first time. I had to send it back to the same mechanic. Hopefully they’ll tell me straight what went wrong. Sometimes it’s about knowing what to ask. I’ll also talk to them and tell them to let me know ALL the details of everything that COULD be wrong so they don’t have to worry that I’ll accuse them of gouging. The shop’s not open til monday and they didn’t have time to get a look at it today.

The problem for your mechanic is that all the corrosion is happening inside the brake lines where it’s invisible and impossible to inspect. All they can do is replace components. It’s your choice as to whether to pre-emptively replace parts that haven’t failed yet.

Since your mechanic used the word “corrosion,” I’m assuming that what failed was a metal brake line, not a rubber nose, since rubber doesn’t corrode.

Unfortunately no one can predict when a brake line will fail. It’s not the fault of your mechanics. But since you apparently have had two consecutive metal brake line failures (but be sure to confirm this with your mechanic first), I would have all other metal brake lines replaced, and all old brake fluid flushed and replaced with new fluid.

I’m puzzled on how the OP can lose all brake pressure. If a brake line begins leaking, then the car will lose only half the braking.

Sure the pedal travel will be farther to the floor and more pressure will need to be applied. But it should not be the complete loss of braking the OP mentions.

I have found that sometimes the “dual-braking” systems don’t really work that well. On one car, when bleeding one caliper, the brake pedal always went to the floor. I remember thinking, “Oh well, so much for the ‘dual-brakes’ myth.”

Me too insightful, I never understood that. The dual system is supposed to eliminate the total failure (I thought) but I’ve bled the brakes on my old Accord probably 50 times, same thing every time, just like you said. Hmmmm. Rocketman

I just got done with the exact same problem with someones car. I replaced the line that went from the ABS actuator to the rear tee. The two lines from the tee to each rear wheel looked ok so I left them be.
When I went to vacuum bleed the brakes I kept getting a lot of air. I hopped in and pumped the brakes a few times and looked under the car. I had a gusher in the front left. I guess while I was replacing the rear main line, I had bumped a front line and caused a weak area to fracture without knowing it. I ended up replacing both front lines next.

The problem also is that many times these lines are hidden under or behind other parts and cannot be inspected. So the best a mechanic can do is to fix whatever is the problem at hand and try his best to inspect the rest.
As far as a mechanic being required to inspect and warn you of any impending doom. He’d have to advise you to replace the entire car. Because at some point something else will go wrong.

The OP only had the car for 6 months and the lines would have shown rusting at that point, but like I said …much is hidden from sight.


Engineers love to design things to make them everything but easy to work on. All automotive engineering students should have to spend an internship working in a garage. :slight_smile: Rocketman



No sense getting all worked up yet, you don’t even know what the problem is. It could be the same line they “repaired” and it failed again. Imagine that. That would be far more concerning to me than another one leaking. These guys aren’t carnac the magnificent. As many have already said, few people want them to proactively fix at any cost even for something as critical as brakes. You tell them you want no failures, you better brace yourself for the ensuing bill. Because if one failed, the rest are surely not far behind…

One line to the rear of my 1999 Honda Civic rusted through last winter. Two brake lines and two fuel lines run close and parallel from the firewall to near the gas tank; the whole bundle has a perforated plastic cover protecting things from flying debris. This cover, however, traps snow and ice and salt, etc. The repair shop said the least expensive way is to just run a new line outside that cover, but I decided to have them remove the cover for a closer look-see and to replace both rear brake lines. This came to about $350.

The front brake lines, in a very different environment, appear to be fine.