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Brake System

How to Pinch Off a Brake Line: Emergency Car Maintenance

How to Pinch Off a Brake Line
Last Updated on Aug 16, 2023 By Lillian Kazmierczak

The sudden loss of brakes, while you are driving is not only frustrating, it is dangerous. Lossing your brakes while driving can lead to an accident. Here we look at what happens when you lose your brakes, signs the brakes are failing, and how to pinch off a brake line.

Brake lines – how they work

Around 1968, vehicle manufacturers began installing the tandem master cylinder. It feeds the front and rear brakes line using separate internal pistons. Individual brake lines mean you never lose the entire braking system, just the front or the rear.

Wear and tear of your brake lines usually involve three parts, the booster, the master cylinder, and metal brake lines.

Three Signs Your Brakes Are Going

Soft brake pedal

A sure sign your brakes are going is that you can easily push a soft or weak brake pedal to the floor, but the car does not brake quickly or entirely. The cause of a soft brake is either the master cylinder or the loss of brake fluid.

To see if it is the brake fluid, you must check the brake fluid reservoir to see the brake fluid level.

If the brake feels normal as you brake and the pedal goes to the floor when you press on it, but the reservoir is at the maximum level, it is most likely the master cylinder, and some of the seals may be bad. Even if you can get some pressure when you engage the brake, it’s probably one and done. Don’t drive the car again until a mechanic has looked at the master cylinder. Don’t even drive it to the shop!

If you’re leaking brake fluid, the level will be lower than normal, or the reservoir is empty or near empty. There’s a chance that the wheel cylinders in your drum brake system are leaking, and the drums are damp on the bottom. Another possibility is that the master cylinder is leaking out of the back seal, and the fluid is going into the brake booster.

These can both leak slowly without any sign of leaking. Neither of these causes the pedal to become soft or the loss of braking. It is a definite sign that you are leaking brake fluid from somewhere, which needs addressing immediately.

Looking under the car should tell you where the leak is. If not, ask someone to pump the brake once you refill the reservoir so you can see the leaking as it happens.

Check brake light comes on

If you start the car and the brake light stays on, it’s pretty safe to say that the problem is the brake line. Somewhere there is a hole, crack, or corrosion where the brake fluid is leaking enough to make the light come on. The light will stay on, which indicates a problem. Get the brakes inspected as soon as possible.

Break line corrosion

As the brake line corrodes, there are no signs of leaking, but the line may start to weep as the corrosion continues. Looking under the car, the line might be damp. Then one day, you brake, and there’s a brake fluid gush.

The pedal starts to feel soft due to the gush of fluid. You still have brakes as the brake fluid manages to get to the wheels. Once the line ruptures, the brakes are softer because of the more extensive brake fluid loss. Eventually, the reservoir is empty, and your brake goes to the floor as you apply pressure. At this point, half of the master cylinder is full, but the other half is dry, and you could have residual braking only.

How to Check Your Brake Line

Step 1: Opening the hood, look for the brake lines. You can start at the brake line reservoir and follow them to the wheels.

Step 2: As you examine the lines, look for fluid streaks wet or dry and wetness on the brake lines or under them on the ground.

Step 3: Sand any rust you find on the brake lines. Also, look for areas where the line is thinner and can start leaking later.

Step 4: If you find areas on the brake line that are sticky or softer than the rest of the line, you need to seek a mechanic and get this issue resolved.

Four Methods to Pinch a Brake Line

Method #1 – Clamps

The purpose of pinching the brake line is to get to a repair shop or home where you can replace the brake line. By pinching the brake line, you stop the leak and maintain the fluid left in the system to have some braking ability. This is still dangerous, and the line should be replaced. Drive slowly and remember this is a temporary fix for a dangerous problem. The drive for help will be nerve-racking at best. Most people do not carry the necessary things to pinch the brakes. Use common sense. If you can’t safely pinch the line, DON’T. Call for tow service and stay where you are.

You can purchase various clamps online or in an auto parts store. They come in metal and plastic and many different sizes. The ones pictured above have a hinged end and an end that screws down to tighten the hose to stop the leak. The manufacturer claims this clamp will not ruin rubber brake lines.

Method #2 – Use a plug fitting

If you want to stop the leak and save the brake line (providing it is worth saving), this will save the system till the caliper is repaired. If the leak is from the caliper end of the brake line, unscrew the hose at the wheel and screw in the plug fitting.

They come in a two-piece set with the screw-in plug and the union fitting, or the union fitting and the screw-on plug in one piece (as pictured above.)

Method #3 – Vise grips

Vice grips are metal, and this pair is 7 inches long. Using the vice grips to pinch the line will keep the existing brake fluid in the line. Since today’s master cylinders have separate lines, you have limited braking abilities, so use caution when braking and don’t speed! Vice grips are for an emergency only, not a permanent fix.

You need to cut the break line to use the vice grips to stop the leak. Using the vice grips, flatten the end of the brake line an inch, then fold it over once, then a second time, and clamp the vice grips on the flat and folded section. Lastly, you need to tie the line and the vise grips to something stable on the car to prevent the line from breaking. Wire or cable ties will do the job well!

Method #4 – Break line and compression fitting

It is safe and easy to pinch off the brake line in this way. Essentially, you are removing and replacing the damaged part of the line. You will have full brakes and can get anywhere safely.

You will have to cut out the leaking section of the brake line. Use the piece you cut out to measure the new brake line section. Place a compression fitting on each end, then put the new line in place and clamp down the fittings. Ensure the metal brake line is spliced to healthy metal to prevent leaking.

Tips for when your brakes fail

The main thing is to keep calm. You have two sets of brakes, so if one fails, you still have brakes.

Pump the brakes

You can build adequate pressure in the brake line to brake and control the car safely by pumping on the brake pedal instead of pressing down in a slow movement.

Stop driving and pull over

Leaking brakes aren’t safe. Pulling over and turning off the car is the safest choice.

Use the parking brake only if driving slowly

Parking brakes are made for parking, not to stop a car while driving. Engaging the parking brake when driving at an average speed could send you spinning into another vehicle, cause an accident, and damage the entire brake system. If you must use the parking brake to stop, do it at a lower speed.

About the author

Lillian Kazmierczak

As far as I can remember, I would say I have been a car nut for my whole life. My father was a car dealer who used to change and repair his cars himself. This gave me the opportunity to get around all sorts of cars and get my hands dirty repairing vehicles from an early age.

A great fan of Japanese quality and German preciosity, my deep passion lies in older models that I believe have a flair that takes me back to my childhood! I also love their extraordinary durability and reliability when compared to today’s modern models.

When not out taking a ride, I enjoy socializing with fellow motorheads online and consuming any car facts and figures I can get my mind on!

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