Metric Wrench’s BMW, Mercedes and Audi Blog featuring all of the latest information from around the automotive industry, the latest industry news, view expert opinions, or just join discussions about your BMW, Mercedes or Audi with other enthusiasts from around the world.

Wednesday, April 7, 2010

Prevent Avoidable Problems and Play it Safe by Changing Your Brake Fluid

According to recent studies, 5% of all serious vehicle accidents are caused by maintenance neglect. Preventative checks will greatly extend the life of your vehicle.
Specialists should always check: fluids, tire inflation, battery, lighting systems, and belts. Brake fluid, in particular, is important this time of year, with record weather hitting many parts of the country.

For many, topping off the brake fluid seems a no-brainer, but what about changing the fluid?

According to the Car Care Council (, brake fluid can become contaminated in 2 years or less. This is because the fluid absorbs moisture, which makes its way through the vehicle's hydraulic system. With heavy braking, moisture in the overheated fluid vaporizes (boiling point of water is lower than that of brake fluid) and braking efficiency is reduced.

At Metric Wrench Billings, we feel that it is best to follow the manufactures recommendations. However in the thirty + years of business I have seen very few brake failures due to not changing the brake fluid and I have serviced a lot of cars that probably haven't had the brake fluid changed until the brake master cylinder or some other part fail. Would they have lasted longer if the fluid was changed? Maybe.

The greatest concern is the fluid will boil due to the heat of hard braking and the brakes will fail. Then it becomes a liability issue, which is probably the main reason the manufacture recommend it every 2 years. The boiling as you know is due to the moisture adsorbed by the fluid lowering the boiling point.

The brake fluid is basically a closed system with a small vent in the reservoir cap and this is the only place that air with moisture can enter the system. In the state of Montana I would guess the amount of moisture that gets into the brake fluid through that vent hole is pretty slight.

Common errors I've seen in servicing/changing brake fluid: Changing only the fluid in the reservoir and not bleeding/flushing the system. This does nothing to prevent the fluid from boiling in the calipers or wheel cylinder which is where the boiling will occur. Using the incorrect fluid, there are several types of fluid, DOT3, DOT4, DOT5 etc. The main difference is the boiling point of the fluid. Using fluid from a container that has be sitting in the shop open to the air. Not bleeding/flushing the fluid when the brake pads or shoes are replaced.

Because of the liability, we suggest following the manufactures recommendations for changing brake fluid. We are careful to use the correct fluid and always bleed the brake with pad or shoe replacement.

Take good care of your car so that it can take care of you. If you are concerned about your brake fluid, visit Metric Wrench Billings today to have a certified technician check it out for you. Visit Metric Wrench Billings today for all of your vehicle solutions today!

No comments: