It is difficult to imagine the work of brakes without a vacuum brake booster. It is difficult to overestimate the work of this device, however, like all others, it is not “insured” against breakdown. Today I propose to talk about the main malfunctions of the vacuum brake booster and how to fix them.
On the one hand, repairing a vacuum brake booster is not particularly difficult if you decide to repair this device yourself. The most important thing is to take into account all the design features of a particular brand of car, the very principle of carrying out repairs is not particularly different.
A little about the device of the vacuum brake booster.
Structurally, the vacuum brake booster is one unit combined with the GTZ. For an advanced motorist, the device of this unit will not seem complicated. The body is divided into two parts: the vacuum part is located on the side of the brake master cylinder, the atmospheric part is on the side of the brake pedal.
The vacuum chamber is connected to the intake manifold with a check valve, which is a source of vacuum. Most often, an electric vacuum pump is used in diesel engines in order to keep the vacuum booster in constant operation. In the event that the engine stops, the vacuum booster is disconnected from the manifold by means of a check valve, which is why the vacuum brake booster is very dependent on the operation of the motor and can only function with a working engine.
After activating the brake pedal by means of the follower valve, the atmosphere chamber is connected to the vacuum chamber and the atmosphere. The brake pedal is connected to a pusher, due to which the follower valve moves. The diaphragm is connected to the GTZ rod from the side of the vacuum chamber, thanks to which the brake fluid is pumped by the piston to the working cylinders.
The return spring returns the diaphragm to its original position after the end of braking. The amplifier design can also include an electromagnetic stem actuator. The ESP system uses an active brake booster and its main purpose is to prevent rollover.
First of all, attention should be focused on the ineffective operation of the braking system, that is, the deterioration in vehicle control (TC), the need to make more efforts in order to brake. The following faults are considered classic:
1. Malfunctions inside the vacuum amplifier itself (rupture of the diaphragm or aging of the rubber of the valves). In this case, the valve will vented air.
2.Depressurization or complete breakage of the hose that connects the engine manifold with the vacuum brake booster. As a rule, such a malfunction is accompanied by a hiss of this device. Be sure to check the tightness of the clamps, as well as the hose for cracks and breaks.
1. If the motor starts to work unevenly (intermittently or troit), it is necessary to diagnose the serviceability of the vacuum amplifier. Often, depressurization is accompanied by air being sucked into the air intake manifold pipe, as a result, the air-fuel mixture entering the cylinders is dramatically depleted.
2. Alternatively, you can try to diagnose the malfunction in the following way: make 5-6 strokes of the brake pedal with the engine “muffled”. After that, in the middle of the stroke, fix the pedal, then start the motor. If the pedal fails during start-up, the vacuum amplifier can be considered working. If the pedal remains stationary, repair or complete replacement of the vacuum brake booster is required.
3. Carry out a visual inspection and look carefully to see if there are any smudges on the body of the vacuum amplifier.
Repair of the vacuum brake booster.
In order to make a repair or replacement, you need to have some skills and knowledge, it will not be superfluous to look into the manual for the repair and maintenance of your car. In addition, you will need tools, as a rule, a standard set is sufficient.
Below I give you a step-by-step instruction on the procedure for repairing a vacuum brake booster:
1. Read in detail the manual (manual) for the repair and operation of the car, determine the key nuances for yourself.
2. Disconnect the booster drive rod from the brake pedal, which is located under the steering shaft.
3. In the engine compartment, remove the GTZ.
4. Depending on the breakdown, repair or completely replace this device.
A Gazelle car arrived for repairs, with a problem - the brakes were gone. The brake pedal became very tight, when pressed, the car even sometimes stalled. The first diagnostics showed that there is a problem with the vacuum brake booster, it needs to be replaced. When you press the brake pedal, a hiss is heard, this means that air is leaking, most likely the membrane of the vacuum cleaner is torn. To replace the vacuum booster, unscrew the stem from the brake pedal, then using a 13 key, unscrew the vacuum booster mounting nuts, disconnect the vacuum hose, turn off the brake fluid level sensor. When replacing, it is not necessary to drain the brake fluid and loosen the pipes. If you notice that you have a torn rubber gasket between the cab and the vacuum, then it is better to replace it.
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For work, you better take an assistant, in some moments you will really need it.
Progress does not stand still, so now it is difficult to imagine a braking system without a vacuum brake booster, which is a necessary element of the braking system. But the vacuum booster can sometimes have problems, so sometimes the vacuum brake booster needs to be replaced or repaired.
Technologically independent replacement of a vacuum brake booster is not so difficult. It is only necessary to take into account all the design features of the car model, since in all models the principles of operation of the vacuum brake booster are the same.
The vacuum brake booster and the brake master cylinder (GTZ) are combined into one unit. The circuit and device of the vacuum brake booster is not so complicated.
The diaphragm divides the amplifier housing into two parts: on the side of the brake pedal - the atmospheric part, and on the side of the GTZ - the vacuum part.
The vacuum chamber is connected to the intake manifold with a check valve. The collector is also a source of vacuum. If the engine is diesel, then, most likely, an electric vacuum pump will be used to ensure the operation of the vacuum amplifier.
If the engine is stopped, the check valve activates the decoupling of the manifold and the vacuum booster. The vacuum brake booster only works when the engine is running. The same disconnection occurs if the vacuum brake booster is faulty.
The atmospheric chamber with the help of a follower valve is connected to the vacuum chamber in the initial position of the valve, and it is connected to the atmosphere when the brake pedal is pressed.
The pusher is connected to the brake pedal and is responsible for moving the follower valve. The diaphragm of the body is connected from the side of the vacuum chamber with the GTZ rod. The pusher pumps the brake fluid by means of a piston to the working cylinders.
The return spring is needed so that the diaphragm moves to its original position until the time when braking ends. Sometimes an electromagnetic rod drive is built into the amplifier design.
If the system is ESP, then it has an active brake booster. The purpose of such an amplifier is to prevent rollover.
The principle of operation of a vacuum amplifier is based on the fact that different pressures are formed in the atmospheric and vacuum chambers. This pressure difference acts on the pusher, moves the GTZ piston rod.
If the vacuum brake booster has faults, then first you need to understand that faults will not damage the brake system. The car will be difficult to drive, and when you press the brake pedal, you need to increase the effort.
There are two traditional faults that require replacement or repair of the vacuum brake booster:
breakage or depressurization of the hose that connects the engine manifold and the vacuum brake booster. In this case, the hiss of the vacuum brake booster will be heard. The hose should be checked for breaks or cracks. Also check the tightening of the clamps;
there may be malfunctions inside the vacuum booster - the rubber of the valves may age or the diaphragm may burst.
Checking the vacuum brake booster is easy. If there are problems with the engine, then the diagnosis should be started by checking the vacuum booster. The consequence of depressurization is air leakage into the intake manifold, which leads to problems with the air-fuel mixture that enters the engine cylinder.
There is another option for checking the vacuum amplifier. If the engine does not work, then a few strokes must be made with the brake pedal. In the middle of the stroke, the pedal is fixed if it falls through. If the brake pedal does not move, then repair or replace the vacuum brake booster.
During a visual inspection, you need to pay attention to whether there are leaks on the body of the vacuum amplifier. If they appear, then you need to find out the reasons for their appearance.
Repair of the vacuum brake booster
The vacuum brake booster is repaired using an appropriate repair kit and standard kit. Replace the vacuum brake booster assembly with a new assembly.
If we talk about the technology of replacing and repairing a vacuum brake booster, then first you will need to familiarize yourself with the car manual, clarify all the nuances of the amplifier design and the manufacturer's recommendations for repair.
Then you need to act according to the traditional scheme:
the traction drive of the amplifier in the passenger compartment is disconnected from the brake pedal;
GTZ must be removed in the engine compartment;
the vacuum hose is disconnected from the check valve.
After the GTZ is removed, a complete replacement or repair of the vacuum amplifier is carried out. It all depends on the malfunction.
Good day, dear motorists! Those of you who once drove old car models probably don't remember how much effort had to be applied to the brake pedal to stop the car.
Fortunately, progress does not stand still, and today we simply cannot imagine a braking system without such a necessary element as a vacuum brake booster. It's not about how the vacuum booster makes the braking process easier, but about such unpleasant moments as malfunctions, repairs and replacement of the vacuum brake booster.
By the way, technologically, the procedure for replacing a vacuum brake booster with your own hands is not difficult. You just need to take into account the design features of each car model, and the basic principle of operation of the vacuum brake booster is the same on all car models.
And, of course, before you repair or change something, you need to know how this “something” works.
The vacuum brake booster is structurally integrated into one unit with the GTZ (master brake cylinder). The device and scheme of action of the vacuum brake booster, for a person with intelligence, does not represent much intricacy.
The ESP system uses an active brake booster. Its task is to prevent rollover.
The principle of operation of a vacuum brake booster is based on the fact that a pressure difference is formed in the vacuum and atmospheric chambers. It is this pressure difference that acts on the pusher and moves the GTZ piston rod.
First of all, you need to understand that malfunctions of the vacuum brake booster do not lead to a fatal failure of the brake system. It becomes difficult to control the car, and an increase in effort when you press the brake pedal.
Traditional malfunctions that require repair or replacement of a vacuum brake booster are:
depressurization or breakage of the hose that connects the vacuum brake booster to the engine manifold. In this case, you will hear a hiss of the vacuum brake booster. Check the hose for cracks or breaks, the clamps are tightened securely;
a malfunction inside the vacuum booster, there may be a rupture of the diaphragm or aging of the rubber of the valves. In this case, the valve begins to "poison" the air.
How to check the vacuum brake booster? Basically, it's easy. First, if your engine has started to "triple", start diagnostics by checking the serviceability of the vacuum booster. The fact is that depressurization is accompanied by air leakage into the intake manifold pipe, which in turn leads to a sharp depletion of the air-fuel mixture entering the engine cylinder.
The second option for checking the serviceability of the vacuum amplifier. With the engine off, make several (4-6) strokes of the brake pedal. Then, with the pedal locked in the middle of the stroke, start the engine. If during starting the pedal "falls through", that is, it makes a movement to the floor, then the vacuum amplifier works. If the brake pedal remains motionless, then it's time to repair or replace the vacuum brake booster.
During a visual inspection, pay attention to the presence of smudges on the housing of the vacuum brake booster, and, naturally, take measures to find out the cause of their appearance.
Repair of the vacuum brake booster is carried out using the appropriate repair kit and a standard set of tools. Replacing the vacuum brake booster, of course, is done with a new assembly.
First of all, you should familiarize yourself with the "smart book", i.e. manual of your car, and clarify the nuances of the design of the vacuum amplifier and the manufacturer's recommendations regarding its repair.
Next, we proceed according to the traditional repair scheme:
in the passenger compartment, disconnect the vacuum booster drive rod from the brake pedal (under the steering shaft);
remove the GTZ in the engine compartment;
disconnect the vacuum hose from the check valve;
After removing the GTZ, we repair the vacuum brake booster or replace it completely. Depending on the malfunction.
Good luck with your booster repair or replacement.
VIDEO Today, hardly anyone can imagine the work of a brake system without a vacuum brake booster. Next, we will talk about malfunctions and how to repair the unit in question. From a technological point of view, repairing a vacuum brake booster is not difficult, even if you decide to carry out the procedure yourself.
It is only recommended to take into account the design features of a particular car model, the basic principle of the repair itself is similar for all models.
It is advisable to familiarize yourself with the device of this unit before direct repair or replacement.
Structurally, the vacuum brake booster is combined with the GTZ into one unit. For a person with developed intelligence, the scheme of action of the element in question will not present any difficulties. The body is divided into two parts, with the atmospheric part located on the side of the brake pedal, and the vacuum part on the side of the brake master cylinder.
With the help of a check valve, the vacuum chamber is connected to the intake manifold, which in turn is a source of vacuum. An electric vacuum pump is often used on diesel engines to keep the vacuum booster running continuously.
When the engine is stopped, the vacuum booster is decoupled from the manifold by the action of the check valve, which is why the vacuum brake booster is only able to operate when the engine is active. In the event of a malfunction or failure of the element in question, a similar disconnection occurs.
Due to the follow-up valve, the atmospheric chamber in the initial position is connected to the vacuum chamber and to the atmosphere when the brake pedal is activated. A pusher is connected to the brake pedal, due to which the follower valve moves. A diaphragm is connected to the GTZ rod from the side of the vacuum chamber, it contributes to the injection of brake fluid due to the piston to the working cylinders.
Due to the return spring, the diaphragm moves to its original position at the end of braking. The amplifier design can also include an electromagnetic stem drive. Active brake booster is used in the ESP system and its main purpose is to prevent rollover.
In general, the operation of a vacuum brake booster is based on the pressure difference in the atmospheric and vacuum chambers. It is due to this difference that the pusher is activated and contributes to the movement of the GTZ piston rod.
The first thing worth focusing on is that malfunctions of the unit in question cannot contribute to the complete deactivation of the brake system. As a result, the control of the car becomes more difficult and the driver is forced to apply more efforts by pressing the brake pedal. Traditional faults include the following:
The presence of a malfunction inside the vacuum amplifier itself, for example, aging of the rubber of the valves or a ruptured diaphragm. In this case, the valve will start etching air.
Breakage or depressurization of the hose, due to which the engine manifold is connected to the vacuum brake booster. In this case, you can hear the hiss of the element in question. Be sure to check the tightness of the clamps and the hose itself for breaks or cracks.
If the engine starts to triple, diagnose the serviceability of the vacuum booster.Depressurization is often accompanied by air leaking into the intake manifold, therefore, the air-fuel system, which enters the engine cylinder, is dramatically depleted.
As a second diagnostic option, make about five strokes with the brake pedal with the engine off. Then, in the middle of the stroke, fix the pedal and start the engine. If the pedal falls during start-up, the vacuum booster functions. If it remains motionless, then it is necessary to replace or repair the vacuum brake booster.
During visual inspection, it is strongly recommended to pay attention to the presence of smudges that may appear on the body of the vacuum amplifier.
The brake booster must be adjusted periodically.
For repair or replacement, you must prepare a standard set of tools or a corresponding kit.
When the effort on the brake pedal is increased, it is necessary to check the performance of the vacuum booster.
1. Press the brake pedal as far as it will go several times with the engine off and, keeping the pedal depressed, start the engine. In this case, due to the pressure difference in the cavities of the amplifier, the brake pedal must move forward.
If this does not happen, check the tightness of the vacuum booster hose connections and, if necessary, eliminate the air leak. If this does not give a positive result, then the amplifier is faulty and must be replaced.
2. To check the tightness of the vacuum booster, open the hood and start the engine for 1 minute.
We remove the main brake cylinder without disconnecting the brake pipes from it How to remove and install the main brake cylinder of a Gazelle car
1. Use a screwdriver to loosen the clamp
2. Remove the vacuum supply hose from the fitting.
3. The hose can also be removed together with the fitting.
4. Remove the lock washer with a screwdriver from the cab side.
5. Holding the bolt of the pusher eyelet with the key "19", with the key "17" unscrew the nut
6. Remove the bolt from the pusher eyelet.
7. Take out two plastic bushings from the pusher eyelet
8. Using the "13" head with an extension from the cab, unscrew the four nuts securing the amplifier to the bulkhead of the engine compartment
10. Remove the paronite gasket.
11. Install the new vacuum booster in reverse order, while for the correct operation of the brakes, adjust the position of the adjusting bolt.
To do this, hold the pusher with the key "8", with the key "10" unscrew the lock nut.
12. Then, with a key "8", unscrewing or tightening the bolt, ...
13. We achieve such a position in which the gap between the mounting plane of the amplifier and the head of the bolt is within 1.35-1.65 mm.
14. After that, hold the bolt and tighten the lock nut.
Having lubricated the plastic bushings, we install the amplifier, and then adjust the brake pedal travel.
To do this, holding the pusher of the amplifier with the key "8" (for clarity, shown on the removed amplifier), unscrew the lock nut with the key "14"
15. Rotating the pusher eyelet, set the distance between the center of its hole and the mating surface of the vacuum amplifier body - 131–133 mm. Install the brake master cylinder.
Video (click to play).
Free travel of the brake pedal with the engine off should be 3-5 mm.
