Why Is Having Brake Fluid Important?
Brake fluid is essential in the power transmission system. When it fails its task, this has dramatic consequences for the car’s safety. Your car can lose braking power in two ways: damage to the brake system or aging of the brake fluid. The brake lines and gaskets in the braking system can cause problems in cars of a certain age. Brake lines are made of copper and will rust if left unprotected sooner or later. The brake fluid then leaks out, and its power no longer transfers to the braking system. The gaskets in master and wheel brake cylinders can also suffer. Brake fluid is slightly acidic and therefore eats away at rubber seals and pistons over time. However, the braking system's most significant wear and tear occur on the brake linings and the discs or the disc drum’s place. Brake fluid can also become unusable over time. Brake oil must reliably transmit the force at high temperatures, which can occur during braking at the wheel brake cylinder. That is why no water is used for the braking systems. Unfortunately, brake fluid is hygroscopic, so just like salt or sugar, it attracts water. The water content rising above a specific value can be fatal for the brakes. The high temperatures in the brake system bring the dissolved water to a boil, which changes from liquid to gaseous form. However, unlike liquids, gasses can be compressed, causing the brake pressure to suddenly drop.What to Pay Attention to With Brake Fluid
Water content
The water content is essential for the quality of the brake fluid. If the oil has already aged, the color changes from bright brown to cloudy green, meaning the dilution is already far advanced. Even if brake fluid still looks impeccable, its water content may have rendered it useless. Clarity about the condition of your brake fluid can only be provided via a test. Thankfully, the suitable equipment is commercially available. The best time to check the brake fluid is at the beginning and end of the winter season — then, it’s very easy to combine the check with a tire change.Oil content
In addition to the brake fluid’s water content, you should also monitor the oil level. In a functioning system, the amount of oil does not change. If you notice a loss, you must check the entire braking system. The leak must be found and repaired before the car is allowed back on the road. Simply refilling is not the correct measure in this case. You should bleed the brake system completely to replace the brake fluid. There is no room for error here. If the knowledge and tools are not available, this task belongs in a specialist garage. A checked and maintained braking system provides necessary safety when driving.How Does Brake Fluid Work?
A brake cannot function without brake fluid. A brake works according to a hydraulic principle; it transfers the pressure exerted on the brake pedal to the wheel brake cylinder, which ensures that the brake pads are pressed against the brake discs. Sooner or later, the brake fluid needs to be replaced because quality deteriorates over time. It absorbs water from the air, which has a lower boiling point than the brake fluid. Boiling the water causes bubbles to form in the brake line, which can seriously compromise braking performance. Dirt can also get into the brake fluid, which can be seen from the color of the fluid. Brake fluid may leak if there is a leak in the brake lines, and this can be easily determined by testing the contents of the brake fluid tank.Types of Brake Fluids
Brake fluids are classified by the DOT designation followed by a number. That figure is related to the boiling point.DOT 3
DOT 3 brake fluid is based on glycol-ether. It has a minimum dry boiling point of 401 degrees Fahrenheit and a wet (measured with about 4% water mixed into the liquid) boiling point of 204.8 degrees Fahrenheit. This type is suitable for the normal use of a passenger car.DOT 4
Additives have been added to DOT 4 brake fluid to increase its boiling point, but they must be replaced more often. It is intended for sports cars, although it can also be used in ordinary cars.DOT 5
DOT 5 silicone-based brake fluid is not compatible with other brake fluids and, if the vehicle booklet does not specifically state that this brake fluid is applicable, it may be disregarded.How to Top-up Brake Fluid
Topping up brake fluid regularly is very important. For the braking system to function properly, there must be sufficient brake fluid. You can easily check the fluid level yourself. There is a brake fluid reservoir on the driver's side in the engine compartment; this is often a small, white, transparent reservoir. A minimum and maximum level are indicated on the reservoir. Ideally, the liquid level is between these two indications. Is the liquid level below the minimum indication? Then the brake fluid must be topped-up. Unscrew the cap and look at the color of the liquid. If the liquid is brown or black, you must change it. If the color is still bright yellow, you can fill the reservoir up to the maximum level with new liquid. Don't forget to screw the cap back on.How to Change Brake Fluid
Because brake fluid attracts water, it must be replaced every one to two years. If you let the liquid sit for too long, the water content will become too high. This can cause a vapor lock, meaning that the moisture in the oil will boil. Boiling will allow air to enter the brake system and the braking system’s effectiveness then decreases, which can cause dangerous situations. Brake fluid only works properly when the fluid is uncontaminated — having water or air in it will negatively affect your brakes’ behavior. Are you going to replace the brake fluid? Then it’s best to choose a liquid with the same specifications as the current one. You don't need any special tools to replace it, so you can easily do it yourself.- Clean the area around the reservoir.
- Jack up the car and remove the wheels.
- Connect the tubing to one of the bleed nipples.
- Drain the system by opening the bleed nipple and pressing the brake pedal.
- Is the reservoir almost empty? Then you can add the new brake fluid. Make sure that the reservoir is not completely empty; otherwise, air may enter the system.
- Then depress the brake pedal a few times until the new fluid is in the hoses.
- Close the nipple again.
