14.2. Pumping of the brake system

Hydraulic liquid is poisonous; immediately wash away the liquid which got on the open surface of skin a plentiful amount of water. At hit of liquid in eyes, its proglatyvaniye, immediately ask for medical care.

Some types of hydraulic liquid are flammable and can ignite at contact with hot components or naked flame. During the work with hydraulic system it is always safer to assume that liquid is flammable and to take the appropriate measures of precaution similar to precautionary measures at work in gasolines.

Hydraulic liquid is aggressive in relation to paints and plastic elements. At hit of liquid on the painted surfaces of a body or on its plastic elements immediately wash away it a plentiful amount of water.

Liquid also is hygroscopic (has ability to absorb in itself moisture from air); excess liquid moisture content lowers a point of its boiling to inadmissible level that leads to dangerous decrease in efficiency of braking.

Old hydraulic liquid can be polluted and is not subject to reuse at all. At a dolivaniye or replacement of liquid in the brake system always use liquid of the recommended type and you watch that liquid was poured from just open capacity.

Models with the ordinary brake system

The correct functioning of hydraulic system is based on the fact that the liquid used in system is incompressible, otherwise the effort made for a brake pedal via the main cylinder would not be transferred to supports of brakes or wheel cylinders. Pollution of brake fluid leads to the fact that liquid gains ability to contract. At the same time there is a feeling of softness when pressing a brake pedal, and also deterioration in functioning of brakes (or, what is even worse, to refusal of brakes).

Besides, eventually there is a pollution of brake fluid in the course of its oxidation and adsorption of moisture from air. At the same time there is a decrease in a boiling point of liquid that can lead to steam formation at sharp braking and, therefore, to decrease in efficiency of braking. For this reason old or polluted brake the kike - the bone is not subject to reuse and has to be replaced, pumping of the brake system is for this purpose made.

When filling system use only pure, new hydraulic liquid of the recommended type and grade; never reuse the liquid extorted from system. Before getting to work, make sure available enough liquid.

If there is a suspicion that in system liquid of the wrong type was poured, components of the brake system, and also its contours have to be washed completely out by new brake fluid of the required type and grade. Besides all consolidations established in system have to be changed.

In case leaks were resulted by loss of brake fluid or air got to system before starting the further procedure make sure that the cause of leak is removed.

Park the car on the flat platform, switch off the engine, establish a transmission control lever in position of the first or reverse gear (for the manual transmission) or install the selector lever in situation "P" (for automatic transmission). Prop up wheels and release the emergency brake.

Make sure that all tubes and hoses are reliably fixed, nipple connections are tightened, and gates for pumping of brakes are closed. Remove caps of boots and clean off dirt from a surface around gates for pumping of brakes.

Unscrew a cover of the tank of the main brake cylinder and add the tank to a mark at most; freely screw a cover into place and you remember that during the procedure the level of liquid should not fall below a mark at least, otherwise the risk of hit in system of air appears.

In shops of automobile accessories there are on sale sets for an independent prokachivaniye of the brake system by one person. If there is such opportunity, it is recommended to use one of such sets as they considerably facilitate the procedure when pumping brakes, and also reduce risk of the return hit in system of the air distilled from it and old brake fluid. If there is no possibility of use of such set, it is necessary to use the basic method of pumping of brakes (assuming participation of two people) which is in detail described below.
When using of set for pumping of brakes prepare the car as it is described above and further follow instructions of manufacturers of set as at use of various sets the procedure can change slightly. Usually the procedure is carried out according to the scheme given below in the corresponding subsection.

There is a possibility of partial pumping of the brake system (that is only one brake line and a support for time). It it can appear enough in case only one contour is open for work, however in more considerably measure it is safer, and therefore it is more preferable, to make full pumping of system.

The description of the procedure of replacement of brake fluid is provided in the Head Routine maintenance.

Pumping order

Pumping requires the help of the assistant.

The choice of sequence of pumping of brake lines is essentially not important as each support has own connection with the main cylinder.

The basic method of pumping of brakes (assuming participation of two people)


1. Prepare a pure glass vessel, the suitable piece of a plastic or rubber tube which is hardly putting on the gate of pumping of the brake system, and a wrench with a cap head of the size corresponding to the gate size. Alternatively prepare for use patent set for pumping of brakes.
2. Remove a boot cap from the gate of pumping of the first support.
3. Put on a gate head a wrench with a cap head, then on the nipple of the gate pull a drain tube. Lower other end of a tube in a glass vessel and add in a vessel the small amount of brake fluid sufficient to close the lower end of a tube.
4. During the procedure you watch liquid level in the tank and do not allow lowering it below a mark at least; if necessary you make a dolivaniye of brake fluid.
5. Let the assistant several times will press a brake pedal for pressure raising in system - then at the last muscleman will hold a pedal of pressed.
6. After pressure raising in system weaken the gate approximately on one turn and allow liquid to follow in a glass vessel. During the procedure it is necessary to support by a pedal pressure in system; if necessary make full squeezing of a pedal of a brake against the stop, however do not release it. After the effluence of liquid will stop, tighten the gate then the assistant can slowly release a pedal. Check liquid level in the tank, if necessary make its dolivaniye.
7. If at the brake system there was an air, then it will be swept up in the form of bubbles, in the liquid quitting the system. Repeat the procedures described in the previous two paragraphs until the liquid following from the gate does not cease to contain air bubbles. If draining of liquid from the main cylinder and a nalivaniye in it new was made, and from the first brake line air is extorted, make an interval between cycles within about 5 seconds for refilling of channels of the main cylinder.
8. After the termination of emergence of air bubbles, strongly tighten the gate, then pick up the phone and a key and establish into place a boot cap.
9. Repeat procedures with the remained brake lines until air is not completely distilled from system, and the feeling of a pedal of a brake will not become firm again.

Not to perezatyagivayta gate.

Prokachivaniye of the brake system by means of set with the backpressure valve

As appears from its name, set consists of a piece of the tube equipped with the backpressure valve which prevents
the return hit in system of the air extorted from it and hydraulic liquid; the structure of some sets included translucent containers which can be installed in such a way that the air bubbles leaving the end of a drain tube will be well noticeable.

Set joins the pumping gate which then opens. The user comes back after that to a driver's seat, smoothly and firmly squeezes out a brake pedal, and then slowly releases it; this procedure repeats until brake fluid, free from bubbles, does not begin to quit the system.

Pay attention that use of this set so facilitates pumping operation that it becomes quite simple to forget about need of support of level for the tank of brake fluid. You watch that the level of liquid was always supported above a mark a minimum, otherwise air can get to system.

Prokachivaniye of the brake system by means of the set using pressure from an external source

Feeding of this set is usually carried out from the tank with the compressed air concluded in a spare wheel. However you remember that in certain cases according to instructions of manufacturers on set food compressed air, dropping pressure in a spare wheel below usual level can be put necessary.

The procedure is carried out by connection to the tank of the main brake cylinder of container with the brake fluid which is under pressure. Pumping of brakes is carried out by simple opening of each gate of pumping in turn and observation of the brake fluid following under the influence of pressure until it does not cease to comprise air bubbles.

This method is good also the fact that use of the big external tank with brake fluid provides an additional insurance from hit of air in system at its pumping.

Such method is especially effective when pumping "difficult" systems or at full pumping of the brake system after replacement of brake fluid in the course of routine maintenance of the car.

All methods


1. After completion of the procedure of pumping of brakes and restoration of strong feeling of a pedal wash away and collect the spilled brake fluid, strong tighten gates and establish into place caps of boots (where are available).
2. Check the level of hydraulic liquid in the tank of the main brake cylinder, if necessary produce dolivany liquids.
3. Remove or hand over the merged hydraulic liquid - it is not subject to reuse. Remember that liquid is poisonous and extremely flammable.
4. Check feeling of a brake pedal if there is a feeling of softness, then perhaps in system still there was an air; repeated pumping of system will be required. In case the prokachivaniye of the brake system during several times does not restore the hardness of feeling of a pedal, the problem perhaps lies in wear of cuffs of the main cylinder (wear is shown at emergence of excessive quantity of vials of air in the tank of hydraulic liquid when squeezing a brake pedal). The procedure of capital repairs of the main brake cylinder is described in the Section Removal, capital repairs and installation to the place of the main brake cylinder.

Models with the ABS system

Brake contours of forward wheels always have to be pumped over before a back contour.

Brake contours of forward wheels

Use one of the methods described above for the systems which are not equipped with the ABS system.

Brake contours of back wheels

Do not allow turning on of the hydraulic pump during time more than 2 minutes for once. After end of this period switch off ignition and let's the pump cool down during time at least 10 minutes. Under no circumstances the pump should not be started dry.


1. Add in the liquid tank to a raising of its level to a mark a maximum. During all procedure of pumping of brakes support level above a mark at least.
2. Put on one end of a piece of a tube the gate of a back support, lower other end of a tube in the liquid poured in a pure vessel.
3. Let the assistant will turn the ignition key in the second situation, then will squeeze out and holds a brake pedal; at the same time the hydraulic pump and pressure in a back brake contour will turn on will rise.
4. A wrench with a cap head (previously put on a gate head) weaken the gate approximately on one turn and allow liquid to follow in a drain vessel. You watch that the pedal was the liquid pressed in the course of an effluence at the open gate.
5. The air which is contained in system will come out it in the form of the air bubbles which are contained in a stream of the following liquid. After the termination of content in the followed liquid of bubbles tighten the gate, release a pedal of a brake and switch off ignition.
6. Wipe a surface around the gate, having cleared it of excess of brake fluid, and establish into place a boot cap.
7. If necessary, the procedure described above can be applied to a brake support of the second back wheel.
8. After completion of pumping of system add brake fluid in the tank so that its level rose to a mark at most, establish into place a cover.