When the brake warning light comes on, the brakes do not respond or the brake pedal goes down you may have a brake fluid leak. Another clue could be a puddle of liquid under the machine: the liquid is colorless and not as thick as engine oil, but has the consistency of normal cooking oil.
Steps
Part 1 of 6: Finding the Leak
The first step is to find the loss and understand how serious it is. Once you understand these factors, you will move on to real repair.
Step 1. Open the hood and find the brake fluid reservoir
It is located on the driver's side, towards the rear of the engine compartment. If the level is low there may be a leak.
Step 2. Check for the leak by checking under the machine for liquid
If you see it, you may also be able to better identify where the leak is.
Step 3. Put newspapers on the floor, roughly where the leak is
Step 4. Press the brake pedal to pump fluid out of the leak
Make sure the machine is off: with the machine on the liquid is sprayed out forcefully and the leak would be difficult to control depending on its severity.
Step 5. Crawl under the car and look for the exact spot of the leak
If it comes from a wheel you may need to remove it to look for the leak in the hoses or calipers.
Step 6. Check the master cylinder
Its positioning varies from car to car, you can find it in the car manual. If you don't have the manual, search online.
Step 7. Verify that the master cylinder is tightly closed
Sometimes there can be leaks if the lid is not closed tightly.
Part 2 of 6: Rebuilding the Brake Calipers
Few mechanics rebuild the calipers, cylinders or master cylinder from scratch. Much more frequently they send parts to a specialized repair center and then reinstall the repaired parts. However, if you want to try your hand at building calipers, you can pick up a kit of those found in auto parts stores.
Step 1. Remove the old pliers
- Buy the kit at a parts store or dealership.
- Remove the bleed screw using a wrench. If necessary, also use lubricant and penetrating oil to loosen the piece without running the risk of breaking it.
- Detach both the steel and rubber tubes with a wrench. Change them if they have cracks or are worn before putting the pliers back on.
- Remove pads, shims, springs, sliders or pins.
- Remove the external anti-dust.
- Put a piece of wood that is slightly thicker than both pads stacked together in the caliper behind the piston.
- Introduce low pressure air into the opening; in this way the piston should come out.
Step 2. Replace the piston
- Lubricate the new piston you find in the kit with some brake fluid.
- Insert the new piston into the caliper by applying pressure with your fingers.
Step 3. Replace the caliper
- Replace the external anti-dust.
- Replace pads, shims, springs, sliders or pins. Use the new parts you find in the repair kit and leave the old ones aside.
- Reattach the steel and rubber pipes.
- Reinsert the bleed screw.
- Check the brakes for leaks.
Step 4. Bleed the air from the brakes
Part 3 of 6: Replace the Wheel Cylinder
Failed cylinders can cause fluid leakage. Putting a new cylinder is much easier and only slightly more expensive than rebuilding the entire piece.
Step 1. Remove the wheel
- Remove the rim and tire.
- Jack up the car so that the wheel is off the ground.
- Remove the bolts and the wheel.
- On the brake hose it sprays penetrating oil, in order to dissolve any encrustation.
Step 2. Remove the brake drum
- Remove the rubber plug behind the support plate.
- Loosen the self-adjusting to lower the jaws. If you turn the wrong way, the drum will tighten and you won't be able to turn it. If needed, use a flat-blade screwdriver.
- Remove the drum.
- Place a container under the brake shoes. If they are covered in liquid, you will need to replace them.
- Spray this entire area with brake cleaning fluid to get rid of dirt and fluid.
Step 3. Loosen the steel brake hose
- Prepare an empty tube to prevent the liquid from escaping. Put a screw or bolt on one end.
- Find the point where the steel pipe screws into the plate in the wheel cylinder and use a wrench to loosen the fitting.
- Remove the fitting.
- Put the empty hose on top of the brake hose to avoid leakage.
Step 4. Replace the wheel cylinder
- Find the two bolts holding the cylinder to the support plate.
- Use a socket wrench to loosen them.
- Remove the old cylinder.
- Insert the hose fitting into the new cylinder. Screw it in by hand as much as you can.
- Insert the bolts back into the support plate and screw them to secure the new cylinder.
Step 5. Bleed all air from the brakes
Part 4 of 6: Replace the brake hoses
If the brake hoses are damaged, have cracks or look spongy, then they need to be replaced. If they have rust stains then try gently scratching them to see if the metal has weakened. If the steel pipes have stains on the walls, change them.
Step 1. Remove the wheel that is above the leak
Step 2. Unscrew the hose from the fitting closest to the master cylinder
Step 3. Remove all fasteners from the mounting bracket that holds the tube in place
Step 4. Detach the tube from the jaws using a wrench
Step 5. Attach the new tube to the jaws without locking it
It should be the same length as the old one.
Step 6. Reinstall the retainers to the new hose
Step 7. Attach the hose to the fitting closest to the master cylinder using a wrench
Step 8. Tighten all screws and bolts
Step 9. Bleed the air from the brakes
Part 5 of 6: Replace the Master Cylinder
Most modern brake systems are divided into two circuits, with two wheels for each system. If one of the circuits does not work, the brakes of the other will instead work. The master cylinder supplies pressure to both of them, and replacing it is cheaper than having it redone in a shop.
Step 1. Open the hood and find the master cylinder
Step 2. Remove the brake fluid reservoir cap
Step 3. Remove the liquid from the master cylinder using a pipette
Put the liquid in a plastic container.
Step 4. Disconnect all electrical parts from the master cylinder
Step 5. Unplug the hoses using a wrench and turning it counterclockwise
Step 6. Remove the master cylinder retaining bolts using a socket wrench
Step 7. Remove the old master cylinder
Step 8. Install the new one by securing the bolts
Step 9. Attach the tubes to the cylinder using a wrench
Step 10. Connect the electrical parts
Step 11. Bleed the air from the brakes
Part 6 of 6: Bleeding the Air from the Brakes
After each brake repair, bleed the air and brake fluid and replace it with new fluid. To do this you will need someone to help you.
Step 1. Ask your helper to sit in the driver's seat
Step 2. Remove the fuel cap on top of the master cylinder
Step 3. Remove all liquid from the cylinder using a blower and place the used liquid in plastic containers
Step 4. Fill the reservoir with fresh liquid
Check the bottom of the cap or your car's manual to see which fluid is best for your vehicle.
Step 5. Loosen the bleed screws located on the calipers or wheel cylinders
Step 6. Attach plastic tubing to the bleed screws
Step 7. Put the other end of the plastic tubes inside the bottles
Step 8. Ask your assistant to press the brake pedal all the way down
Step 9. After all bubbles have come out, tighten the right front bleed screw
Step 10. Ask your assistant to slowly return the brake pedal to its starting position
In this way, the liquid will enter the main cylinder body.
Step 11. Ask your assistant to depress the brake pedal again
Tighten the bleed screw of another wheel as soon as all the air bubbles have come out. Repeat the process for all wheels.
Step 12. Fill the master cylinder with brake fluid
Step 13. Check the brakes to make sure they are working properly
Advice
- If you feel the brake pedal still spongy after you finish the job, you will probably need to bleed some more air.
- To remove the pipes you can use an open wrench. However, this type of wrench can damage the steel, so spray the entire work area with penetrating oil when you remove the pipes.
- If you repair a set of brakes remember to do the same thing on the opposite side as well. Always consider the brakes as an axle and do not repair them individually.
Warnings
- Follow the car's manual to jack up the vehicle.
- Always wear protective clothing, eye mask and gloves when dealing with brake fluid.
- Be careful not to damage the bleed screw when you unscrew it.
- Follow the local ordinances regarding the disposal of brake fluid.
