Do-it-yourself brake fluid replacement.

March 18, 2016 Lada.Online 29 063 0

Replacing the brake fluid in the hydraulic brake system on modern Lada models (Granta, Kalina, Priora, Niva 4x4, Vesta and XRAY) should be done every three years or after 45,000 km (whichever comes first). On Lada Largus - once every six years or after 90 thousand km. mileage All cars have the same type of brake design, so the process for changing brake fluid is similar.

Existing types of ABS systems

The sequence of changing ABS brake fluid is essentially a simple and trivial procedure. Despite this, the modern auto industry takes into account safety trends: almost all car models are produced with ASC and EBD systems installed. These components are controlled by the exchange rate stability system - ESP.

In this regard, replacement of TZ is carried out only in authorized service centers. The reason for this lies in the need to connect the ECU to a diagnostic scanner. On those cars in which the valve system and pump with hydraulic accumulator are represented as separate units, it is impossible to change the brake fluid yourself for the same reason.

Brake fluid tester

It is quite difficult to determine exactly when the need for maintenance arose. Theoretically, it is possible to check the parameters of both new and used brake fluid using a special tester that measures the electrical conductivity of the composition.

It is assumed that the more water in the composition, the higher the electrical conductivity. But it's not that simple.

• The device reacts differently to the chemical composition of additives used by manufacturers.
• Commercially available tester models are not distinguished by high quality and reliability of readings. However, it is possible that you will become the owner of a device that does not have these shortcomings.
• Modifications that provide adjustment of parameters according to the standard are considered more advanced. But in this case, the question remains open about where to get the reference brake fluid for these purposes.

Instrument models that are reliable and capable of giving reliable readings are expensive.

Therefore, it is better to carry out not measurements, but the maintenance recommended in the technical specifications of the car.

Why do you change the brake fluid in a car?

The main task of the brake fluid is to transfer energy from the master cylinder of the system to the brake cylinders and pads. The frequency of its replacement is set by the manufacturer: the procedure is carried out every 1.5-2 years or every 35-40 thousand kilometers. This frequency corresponds to the normal operation of the vehicle.

The brake fluid is also changed if the brake system breaks down, especially if moisture has gotten into it. TJ itself is a very hygroscopic composition, and if it absorbs water, it immediately loses its characteristics. The brake system in a car is not completely sealed, which is why water can enter it through compensation holes.

Another reason for changing fuel oil is a common mistake - mixing different auto fluids. Of course, this can be done, but you need to take into account a large number of factors and parameters - engine model, composition, characteristics of the fluid itself, type of additives, operating conditions, and others. It is acceptable to add a small amount of the composition, but experts strongly advise a complete replacement of the fuel fluid.

The best option is to replace the fluid with a similar one from the same manufacturer and the same brand.

Myths about brake fluid

There are several misconceptions about TJ, which are taken for granted by many drivers.

The first myth is the closed mode of brake fluid operation. Compensation holes present in the brake system of a car are responsible for the movement of air inside it. Along with air flows, moisture vapor gets inside and is absorbed by the fuel fluid, which leads to a loss of its properties.

The second myth is about the possibility of mixing different liquids with each other. Of course, this can be done, but not in every case and not with all compositions. Depending on the car model and its design features, certain standards are applied in the production of the vehicle. For this reason, you can add liquid of a different brand and manufacturer, but in extreme cases and in small quantities.

The third myth is that fluids that meet the DOT-4 standard can be poured into any car. This is not entirely true; A specific type of fluid corresponds to a specific make and model of a car. You should adhere to the requirements of the car manufacturer - safety and life are much more expensive than the price paid for a bottle of TJ.

Need for replacement

Brake fluid transmits force from the brake pedal through the master cylinder to the wheel cylinders, which operate the brakes on the wheels of the vehicle. In order to provide effective braking, the fluid must:

• Maintain its characteristics in a wide temperature range (from -30 °C to +150 °C and above).
• Be non-aggressive towards rubber products and metal surfaces of system parts.
• Possess high lubricity to maintain reliable functioning of brake cylinders.

In addition to the fact that these properties gradually deteriorate during operation, it is also necessary to take into account another important parameter: hygroscopicity. It characterizes the ability of a liquid to absorb and retain moisture from the air.

Moisture increases the corrosive effect on the metal elements of the brake system and increases the risk of boiling.

When the water content increases to 3%, the boiling point decreases by approximately 70 °C. When water boils, steam is released, which is well compressed. This can lead to “failure” of the brake pedal and a sharp drop in braking efficiency. It is precisely because of its hygroscopicity that brake fluid should be replaced not according to mileage, but regularly (every 2-3 years).

Selecting the right type of liquid

In order to choose the right type of fluid to use, you must refer to the vehicle’s operating manual and familiarize yourself with the manufacturer’s requirements. There are four main classes: DOT 3, DOT 4, DOT 5 and DOT 5.1. They all differ in composition, so mixing liquids of different classes (or even the same class, but produced by different manufacturers) is highly not recommended. This is especially true for DOT 5, which is made on a silicone basis; it cannot be mixed with other types.

Preparing for work

In order to replace the brake fluid, first of all you need to prepare the necessary materials and equipment:

• Fresh liquid.
  A wrench that will help unscrew stuck brake pipes
• Socket wrenches 7-8 mm (for older cars) or 9-11 mm (for newer cars).
• Transparent plastic or silicone tubes with a diameter of 4 mm or 6 mm (depending on the diameter of the bleeder fitting).
• A transparent container (a 1-1.5 liter plastic bottle is best).
• Jack (if the procedure is not carried out on a lift, trestle or inspection ditch, several jacks will be needed to simplify the procedure).

In addition, replacing brake fluid requires the involvement of an assistant.

It is also necessary to determine which brake circuit circuit is used on the vehicle. The sequence of work depends on this:

• Diagonal (“crosswise”) - first the rear right wheel is pumped, then the front left, then the rear left and front right.
• Parallel - pumping begins from the rear right wheel, then the work is done alternately on the rear left, front right and front left wheels.

Before performing work, you need to find the bleeder fittings on the brake mechanisms, if necessary, clean them of dirt and remove the rubber caps.

Methods for replacing brake fluid

It is advisable to fill in fresh fuel oil at a car service center. Actually, this thought comes first to the minds of many drivers. In this case, there is no need to delve into the car yourself, armed with keys and climbing into the inspection hole. The car service has special equipment and professional specialists.

However, it is worth remembering that the services provide only the replacement of brake fluid, nothing more. In addition, the final price may increase significantly due to additional work.

The second option is to replace the fluid yourself. It is much cheaper - its price is measured only in the cost of the vehicle itself and its own labor costs, it is profitable and also includes a visual inspection of the car and its condition.

In the second case, the first thing you need to do is look into the car’s operating manual and take an interest in the diagram, or design, of the brake system. It can be parallel or diagonal.

The brake fluid is replaced one by one in the circuits. In the first case, they start with the right rear wheel, move to the left front, left rear and right front. In the second - from the right rear, left rear, right front and left front wheels.

To make it easier to change the fluid, it is better to lift the car onto an inspection hole or overpass and remove the wheels from it, observing safety rules. After filling in the new product, the brakes are completely bled.

Replacement with ABS system

The presence of an ABS system complicates this procedure due to the fact that the modulator must also be inflated. And for this you need to create excess pressure in the expansion tank. You need to create a special device to pour the solution. To change the brake fluid, you will need another reservoir cap, a bulb (you can get it at any pharmacy) and a piece of pipe with a valve. You need to install a pipe on the lid. According to the instructions, to change the brake fluid in cars with ABS, you need to create a pressure of 1 bar on the tank.

First, the old liquid is pumped out of the reservoir and new is added. Then they pump the wheels. Fill the tank with as much liquid as possible. Close the lid and insert the bulb under pressure. After this, place the tube on the fitting and insert the other end into the container (mineral water bottle). Using wrench 10 you need to unscrew the bleeder screw.

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When old fluid comes out, pump it until all the dirty fluid comes out. You can determine this condition visually. Then close the fitting with force and fill the brake fluid to the upper level. Reinstall the factory cover. That's it, this procedure has been successfully completed.

Changing ABS brake fluid

This process can be seen in the video:

In the braking system of a car with ABS, when replacing a TJ, several nuances should be taken into account. As a standard procedure, the procedure is carried out provided that the pump, accumulator and valve block are located in one unit.

If the ABS system is separate, then it is better to change the fluid at a service center. In such a situation, the fuel fluid is poured into the system with a special device under high pressure, which eliminates the possibility of air entering.

In brake systems with SBC or ESP units, brake fluid can only be replaced using a special installation. This is explained by the fact that during such procedures, the sequence of opening the hydraulic module valves plays a huge role, which is impossible to do on your own.

To replace the brake fluid with your own hands in an ABS system you will need:

• Transparent container.
• Transparent hose 20-30 cm long.
• Keys for 8 and 10.
• Pear or syringe.

The procedure is carried out as follows:

• Fresh composition is poured into the tank.
• The right and left front cylinders of the brake system are pumped.
• The rear right cylinder is pumped, at the same time the pump is turned on and the brake pedal is pressed.
• The rear left cylinder is pumped with the hydraulic pump on.
• The tightness of the system is checked.

If there is a drain fitting on the ABS module, all cylinders are pumped, after which the installation is “run” under excess pressure.

Changing brake fluid yourself is best done only in extreme cases and on cars produced before 1990. The best option for changing the brake fluid is to contact a service center, where they will carry out the entire procedure correctly without compromising the tightness of the brake system.

Carrying out work

The procedure for replacing the solution is slightly different for cars with and without ABS. If the battery, pump and ABS valve apparatus are included in one unit, you can replace the TJ with your own hands. But if the battery is located separately, replacement must be done at a service station, since this requires special equipment that provides additional pressure in the system.

Before describing a simple solution replacement in accordance with the rules, it should be clarified that this procedure is carried out separately in each of the brake system circuits. Therefore, before carrying out it, you need to read the instructions or technical documentation, find out the structure of the specified system in order to understand in what sequence and what to do.

Replacement sequence:

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1. They check what solution is poured into the car’s tank and buy it from the same group. Liquids from the DOT-4 group are often used. It is important not to add a solution that has been open for a while. An open bottle may contain water, which in turn can have dangerous consequences for driving.
2. Place the car on a stand or ride the car onto an elevator and remove all the wheels.
3. Find a tank with a solution under the hood of the car, unscrew the cap and add a new one to the one that is currently in the tank so that the liquid does not come out of the container after topping up. Because we do not remove the solution before adding new solution, blockages in the brake system can be avoided. Gradually add the remaining solution to the tank, draining the old liquid.
4. Pump out the used solution. To do this, go to the breather, located far in the brake cylinder. This is usually the right rear of the car. Continue the sequence.
5. When moving to the right, a breather is placed on the brake caliper at the rear of the car, and a transparent rubber hose is put on it. The other end of the cable is inserted into a pre-prepared waste liquid reservoir. This prevents contact with used brake fluid. In addition, this will also prevent air from entering the brake hoses, provided that the hose tip is immersed in the worn and connected container.
6. You need to ask an assistant to sit behind the wheel of the car and put your foot on the brake pedal. Then you should pump the brake pedal several times to increase the pressure in the brake system. The next step is to press the pedal to a clear mark and hold it until further notice. When one person presses the brake pedal, another person unscrews the vent on the brake caliper, inserts a pre-prepared container under the rubber hose and monitors the waste fluid. The color of the leaking liquid should ultimately be the same as that of the new material.
7. If the color of the liquid still leaves much to be desired or bubbles appear in the liquid, but the pressure of the exiting solution has decreased significantly, you need to close the air valve, remove your foot from the brake pedal and then pump it again. This is to increase the pressure and then hold the brakes to full again. Then unscrew the breather again, from which the solution will begin to flow out again under the influence of high pressure. You need to remember that the brake pedal is pressed all the time when the valve is on.
8. At the moment when the color of the outgoing liquid is the same as that which was poured into the reservoir under the hood, and if air bubbles no longer appear in the filtered solution, it is necessary to turn off the air valve. Only in this case can the person getting behind the wheel take his foot off the brake pedal completely.
9. Then install the wheels and check the effectiveness of the brakes in a safe place.

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