Checking & adjusting brake fluid

Part 1. Preparation and safety

Objective

• Check and adjust brake fluid level.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing – such as coveralls and steel-capped footwear
• Eye protection – such as safety glasses and face masks
• Ear protection – such as earmuffs and earplugs
• Hand protection - such as rubber gloves and barrier cream
• Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

• Never use any petroleum or mineral based products, such as gasoline, kerosene etc, to clean a braking system or its components. They are not compatible and will result in a failure of the braking system and its components. This may result in injury to the passengers or damage to the vehicle.
• Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.

Points to note

• Brake fluid can damage the paintwork by softening the base paint.
• Brake fluid has a hygroscopic nature; it will absorb moisture rapidly. Always replace the cover or lid as soon as possible.
• The higher the D.O.T. number of the brake fluid, the higher its boiling point.
• Do not mix any D.O.T. 5 silicone-based brake fluid with a D.O.T. 3 or 4 glycol-based fluid because they are incompatible.
• As glycol-based brake fluid absorbs moisture its boiling point is lowered. This can cause the phenomenon known as 'brake fade'.
• Brake fluid is stored in the master cylinder. If you are unsure of its location, consult the vehicle's shop manual or the owner's manual.
• If your vehicle has antilock brakes, consult the owner's manual before filling the cylinder.
• If brake fluid splashes into your eyes, rinse it out with tap water immediately.
• Do not swallow brake fluid. It is toxic.
• Brake fluid reservoirs will indicate the maximum and minimum levels with a marker on the side or level bars inside the container.

Part 2: Step-by-step instruction

1. Check brake fluid
   Wipe around the master cylinder top cover to prevent any dirt from entering the system. Open the top of the master cylinder, by removing the plastic lid, or by prying the retaining clamp from a metal cover. Look inside the master cylinder. The fluid should be up to the “FULL” line on the side of the cylinder or within half an inch of the top of each chamber.
2. Adjust brake fluid
   Add the manufacturer’s recommended brake fluid only if needed. Replace the cover and check that it is fully seated.
3. Final inspection
   Check for any leaks around the master cylinder with a flashlight. Dilute any brake fluid that may have been spilt with fresh clean water. Do not rub the fluid with a cloth.