Do brake lines get damaged from bending too much?

[waleed]

I have a 2008 toyota yaris and my lines near the master cylinder are all factory poly coated. I had taken the master cylinder off many times to check for leaks for a very slow leak ive been having. I had a aftermarket dorman that failed in about a year, and my old oem one is starting to go. I checked the lines and there are no leaks. I recently moved the lines a lot pulling it in and out checking for a rear seal leak on the booster without unhooking them, and my car has a factory clamp attahed to a bracket on a bolt that holds other brake lines, and when you move it, it bends the rear nut. The two nuts attached to the master seemed to have gotten alot of stress. They arent leaking but should I replace them? One of them needs a new nut since its stripped but the other seems fine. The line nut nearest to the booster has had the most wear. These two lines are pretty small and join a union.

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[Mike]

As the metal fatigued enough to be a concern, I believe you would see a kink in the tubing.
You can order a preformed replacement line from Toyota.

The way to prevent the brake line fittings from getting damaged is to only loosen or tighten them with flare nut wrenches aka line wrenches.
These wrenches go almost totally around the fitting with only an opening to enable you to slip the wrench over the line.

Are you 100% certain you actually have a slow fluid leak?
As brake pads and shoes wear, the caliper pistons and wheel cylinder pistons move outward to compensate, which lowers the fluid level in the master cylinder.

If you are sure there’s a leak, have a careful look at the wheel cylinders.
When the internal seals start to leak, fluid accumulates behind the dust boots that covers the piston.
This makes it less obvious that there’s a leak.
On some cars you can gently lift the dust boots to have a look.
On others, there’s a metal reinforcing ring on the boot which prevents you from doing this.
Eventually, the fluid seeps past the dust boot, making the leak more noticeable.

[waleed]

I didnt see a leak but I replaced the mc. The only thing I am concerned about is the metal line from bending it too much, but it isnt leaking so should I just leave it?

[Mike]

If there’s no visible damage to the line itself, then you should be ok leaving it.
Of course, if it’s going to bother you, then it’s simple enough to buy the replacement pre-formed line from Toyota.

[waleed]

You can tell one tiny part of the line has a small indentation all the way around where it meets the mc. No leaks. Right where the tube nut is.

[Richard Kirshy]

Hard brake lines can take a bit of abuse.
Nominal flexing over the length of the line should not cause any major issues.
Flexing the line to the point where it kinks is different story all together.
As to the striped nut fitting.
You have basically two choices.
Replace the entire line and fittings with a factory or aftermarket equivalent or cut the damaged fitting off ( with minimal loss of hard line ) replace the damaged fitting and re flair the line.

[waleed]

I replaced that fitting with an old one I had laying around. Only thing Im worried about is that small section of line that has an indentation from moving it in and out with the lines attached. Its right where the rear fitting is on the master cylinder. Its not kinked but u can see a grove around the circumference of one area where it took a lot of strain. It isnt bulged but looks like its pushed in about a mm all the way around. Hasnt leaked.

[Richard Kirshy]

My suggestion..
If in doubt, replace it.
Your life or some others is not worth the cost of a replacement brake line.

[Mike]

Obviously, the line is damaged.
Buy a replacement and be safe.

[waleed]

I ended up getting a 8 inch preflared line and bending to get the shape

[Author]

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