When you read your Owner’s manual or look up scheduled maintenance for your vehicle, whether it is an Audi, a Volkswagen or any other import or domestic vehicle, you will notice that a Brake Fluid service is part of the “To Do” list. But what is really being accomplished when exchanging the brake fluid in your vehicle ?
Brake fluid is hygroscopic, meaning that it is capable of absorbing moisture. Moisture can enter the fluid through a variety of ways including hoses and rubber seals & exposure to air. Moisture means that the fluid is less effective in helping you stop your vehicle = Not Good. Brake fluid is subjected to extremely high temperatures and must have a high boiling point to keep it from turning into vapor in the brake lines. Vapor displaces fluid and is able to be compressed so if you press your brake pedal to the floor, the vehicle may not stop. This fluid must maintain a constant viscosity under varying temperatures, from very hot to very cold so it is very important that the fluid is correct for the vehicle and is changed on a consistent basis. In addition to causing safety issues, water/moisture in brake fluid can lead to corrosion in brake calipers and pistons, the master cylinders, steel brake lines, and the ABS module.
We recently had a VW customer that came in with low brake fluid. She had been adding brake fluid to her vehicle but the level was low after a few days. When she brought her car into the shop, we performed a visual inspection and founds all sorts of issues. Fluid was leaking around the master cylinder and by frequently adding more brake fluid, the fluid made its way into the brake booster, intake manifold, vacuum hoses, shorted out the electronic vacuum pump and was a general mess. Additionally, brake fluid is very caustic and degraded many of the hoses that it touched. (* See accompanying pics).
As you can see, servicing the brake fluid in your Audi or Volkswagen is very important and is typically recommended every 2 years, depending on your driving habits. Brakes and brake fluid are part of our inspection when you bring your vehicle to Das Autohaus. What may seem like a minor maintenance item can turn into something much larger and safety-related if left untouched.