Tips for handling brake fluid

Dec. 5, 2001
How your fleet stores, handles, and disposes of its brake fluid can either help it save – or lose – money. Here are some tips to keep the savings high
How your fleet stores, handles, and disposes of its brake fluid can either help it save – or lose – money. Here are some tips to keep the savings high and the losses low.

Wagner Brake Products, a division of Federal Mogul Corp., has a few tips for fleets when it comes to the handling and disposal of brake fluid – tips that can help fleets costly avoid problems.

First, fleets have to understand what kinds of brake fluid exist. The U.S. Department of Transportation issues specifications for the three main kinds in use by the automotive and trucking industry brake fluid. Those types are DOT-3, DOT-4 and DOT-5. DOT-3 and DOT-4 are glycol-based fluids, which absorb water, while DOT-5 is silicon-based so it doesn’t absorb water.

The key consideration with brake fluid is its boiling point. If brake fluid boils and becomes a gas, it loses most of its ability to transmit force – that is, the ability to stop a moving vehicle by partially or completely disabling the brakes. Brake fluid is also most likely to boil during a period of prolonged braking – not the time when a trucker wants the brakes to fail.

If DOT-3 or DOT-4 brake fluid absorbs water, its boiling point decreases. Since both of those types of brake fluid can absorb water from the air, it is critical that you keep brake fluid containers tightly sealed. Though DOT-5 fluid does not absorb water – meaning its boiling point remains relatively stable – it also means that any water that gets into the brake system forms water ‘pockets,’ which can lead to brake corrosion.

Wagner Brake Products adds these other brake fluid handling tips for fleets:

  • Always store brake fluid in its original container and make sure the cap is very tight. Store it in a clean, dry area away from dampness.
  • Never reuse brake fluid that has been drained from the brake system or even fresh fluid that has been allowed to sit in an open container, because brake fluid is quickly contaminated by dust, air, and moisture.
  • If your brake system uses DOT-5 brake fluid, do not add either DOT-3 or DOT-4 fluid. They can react badly with each other and corrode your brake system.
  • Never use brake fluid with a DOT rating lower than recommended in the owner’s manual. Brake fluid with a low DOT rating could boil and cause soft brake operation.
  • Do not spill conventional glycol-based DOT-3, DOT-4, or DOT-5.1 brake fluid on your vehicle as it will ruin your truck’s body paint. However, silicone-based DOT-5 fluid will not harm most paints.
  • Do not overfill your master cylinder reservoir. Always leave room for hydraulic fluid to expand when it gets hot. Conversely, never permit the master cylinder reservoir to become empty or low.
  • Never clean brake system components with mineral-based solvents such as kerosene, gasoline, acetone, or paint thinner. Such fluid will damage rubber cups and seals by causing them to soften, distort, or swell, causing the brake system to fail.
  • Repair shops occasionally deal with small amounts of brake fluid. Depending on the additives used, brake fluid may or may not be hazardous. However, it can become hazardous when it is contaminated with brake cleaner from a spray can, which contains chlorinated solvents. Because brake fluid is not crude oil-based, it should not be added to used oil.
  • Collect brake fluid in a separate, marked, closed container and identify a waste management company that will recycle it.
  • Determine through testing if your brake fluid is hazardous, and manage it accordingly.
  • If your brake fluid is determined to be non-hazardous, check whether the landfill will accept brake fluid absorbed with cat litter.
  • Don’t put brake fluid into your used oil container.
  • Don’t pour brake fluid down any drain or on the ground.
  • Don’t spray brake cleaner around brake fluid.
About the Author

Sean Kilcarr | Editor in Chief

Sean previously reported and commented on trends affecting the many different strata of the trucking industry. Also be sure to visit Sean's blog Trucks at Work where he offers analysis on a variety of different topics inside the trucking industry.

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