How to Check a Vehicle’s Brake Fluid and Lines

When you put your foot on the brake pedal, the fluid in the master cylinder moves down the brake lines to the front and rear brakes. If there’s insufficient brake fluid, air is introduced into the brake lines and your vehicle doesn’t stop properly. Therefore, it’s important to keep enough brake fluid in your brake fluid reservoir.

To check your brake fluid, do the following:

1. Clean the top of the reservoir carefully.

   A small amount of dirt falling into the fluid can cause the internal seals of the master cylinder to fail. Your brakes will begin to lose effectiveness and ultimately fail completely.

2. Open the top of your brake fluid reservoir.

   If you have the kind with a little plastic reservoir on top, just unscrew the cap of the reservoir. If you have a metal master cylinder that contains the reservoir, use a screwdriver to pry the retaining clamp off the top.

   Don’t leave the master cylinder uncovered or an open can of brake fluid sitting around for too long. Brake fluid soaks up moisture to keep it from settling in the hydraulic components and corroding them. If moist air gets to brake fluid for as little as 15 minutes, the fluid is ruined. So don’t dawdle, and keep the can tightly closed until you’re ready to use it.

3. Look to see where the fluid level lies; make sure that the brake fluid level is within half an inch or so of the cap.

   If the level isn’t high enough, add the proper brake fluid for your vehicle. If the brake fluid reservoir is empty when you check it, you may have to bleed the brakes system.

4. Check the color of your brake fluid.

   Because brake fluid deteriorates with use, it should be replaced by a mechanic if it’s dark in color.

To check your brake lines, do the following:

1. Check carefully along the brake lines.

   Wetness and streaks of dried fluid are signs of trouble.

2. If you see rust spots on your lines, gently sand them off.

   Also look for thin places under those spots that may turn into holes before long.

3. Feel the rubber parts of the brake lines.

   You are looking for signs that the rubber is becoming sticky, soft, spongy, or worn.

   Your brake lines should last the life of your vehicle. If they look very bad, have a professional take a look at them and tell you whether they should be replaced. If the vehicle is fairly new and the brake lines look very bad, go back to the dealership and ask them to replace the lines free of charge.

4. Look at the inner surfaces of your tires.

   Leaking wheel cylinders are indicated by dripping.