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How to Check Your Car's Brake Fluid

When you need to stop your car in a hurry, your brakes need to be functioning at optimum performance. Check your brake fluid when you perform any routine maintenance on your car.


  • : If you have anti-lock brakes, consult your owner’s manual before checking your brake fluid. Some ABS systems require you to pump the brake pedal before opening the brake fluid reservoir.
  • Step 1: Locate the reservoir Look under the hood of your car -- on the driver's side, near the back of the engine -- and find the master cylinder, which holds the brake fluid reservoir.
  • TIP: If you can't locate the master cylinder, consult the vehicle's owner's manual.
  • Step 2: Clean the top of the reservoir Clean off the top of the reservoir with a rag before opening it. Even a small amount of dust or dirt in the brake fluid can damage the seals in the master cylinder.
  • TIP: Be careful not to let any brake fluid drip onto the car. Brake fluid is corrosive and will damage paint.
  • Step 3: Open the reservoir Unscrew the cap, or release the retaining clamp with a screwdriver if you have an older car model.
  • Step 4: Check the color Check the brake fluid's color. If the color is darker than apple juice or iced tea, have a mechanic replace your brake fluid.
  • TIP: Have your brake fluid changed about every 2 years.
  • Step 5: Check the level If the color is OK, look into the reservoir to determine the fluid level. It should come within half an inch of the cap. Add more brake fluid if the level is too low, until the fluid level is at the "full" line, or about 1/4-inch from the cap if there is no visible line.
  • TIP: Only use fluid from a newly opened container.
  • Step 6: Replace the cap Replace the master cylinder cap securely.
  • FACT: The 4-wheel hydraulic brake system was invented by Malcolm Loughead in 1918.

You Will Need

  • Owner's manual
  • Clean rag
  • Screwdriver
  • Brake fluid
  • Mechanic

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