The brake system is the most important active safety element in a car, so its optimal maintenance is vital. In addition to the pads and discs, we must check the condition of the brake fluid.
It is relatively common to pay attention to the wearing parts of a vehicle, but not so much to the liquids that make it possible to function. The most common in maintenance operations is engine oil, but there are others that are equally relevant that we must monitor to prevent degradation.
The brake fluid it is one of them and, without a doubt, it is vital for your safety. Its function is simple: to enable the force exerted on the brake pedal to be transmitted to the cylinders that actuate the brakes.
When to change the brake fluid?
The brake fluid is housed in a closed circuit, but over time it loses its properties and must be replaced. The reason is that it is a hygroscopic liquidthat is, it attracts and absorbs moisture.
MOTOR COUNCIL.ES
Schedule a brake fluid change every two years and never wait more than four
This is important because thanks to this it prevents water from causing corrosion and freezing. But, on the other hand, the percentage of moisture present in the brake fluid increases progressively and, if it is not changed, it will end up forming steam bubblescorrosion in the ducts and an increase in the wear of the pistons.
How to choose the correct brake fluid?
There are several types of brake fluids, so it is mandatory to choose the right one for our vehicle. In essence, each product is differentiated by its DOTdenomination that regulates quality.
To determine it, it is important Boiling point of the brake fluid, since it determines from what temperature it begins to ‘boil’. That is, it goes from a liquid to a gaseous state.
This is especially relevant, since the brakes reach very high temperatures, especially if we drive on secondary roads and steep and long descents such as those of a mountain pass.
Image taken from Buycarparts.co.uk
The types of brake fluid are:
TOD 3: Made with a mineral base from glycol ethers, it is the most used type of brake fluid in conventional brakes, since it is the cheapest. Its dry boiling point is 205 ºC and wet 140 ºC.. Its viscosity grade is 1500 units (cSt). Its main drawback is that it absorbs water easily, making it prone to system corrosion.
Doc 4: is very similar to the previous one, but includes borate esters. It is recommended in conventional brakes and system with ABS. It offers more durability and performance than DOT 3, since its dry boiling point is 230 ºC and 155 ºC when wet. Its viscosity is 1800 cSt.
Doc 5: It is synthetic base. Its boiling point is 260 ºC and it is especially suitable for vehicles that spend time without moving. The sensation it gives when stepping on the brake is more spongy, since it has a low solubility of air in its bases.
TOD 5.1: This is a DOT 4 liquid (also called DOT 4 plus or Super DOT 4), but it meets DOT 5 boiling point and viscosity standards. The dry boiling point is 270ºC and the wet boiling point is 270ºC. 180 ºC, offering a viscosity of 900 cSt. Being smaller than usual, there is a greater risk of leakage from the circuit if it has a crack.
Symptoms that indicate the need to change the brake fluid
The best thing you can do for your brake fluid and for your safety is to strictly follow the maintenance schedule that the manufacturer has programmed for your vehicle. But, in any case, it is convenient that you know what happens when the brake fluid begins to lose its properties.
The first thing you can do is perform a visual exam. First, check the level, which must be above the minimum mark. Then, open its tank -located in the engine compartment- very carefully, as we are talking about a corrosive liquid. Introduce an absorbent white paper and observe the color. If it’s too dark, it’s time to make the change.
Regarding driving, if you notice that the brake pedal is lower, has more travel or presents a spongy touchthen the brake fluid is in poor condition or insufficient due to a leak in the system.
Do not play it with the brakes, ensuring your safety and that of yours is priceless!