Checking hydraulic brakes
With the engine running, press the brake pedal with a force of approximately 120 kgf. Check for leaks in the brake master cylinder, hydraulic brake actuator and every connection.
Checking the operation of the vacuum brake booster without the use of instruments
For a simple test of the operation of the vacuum booster, do the following.
Start the engine, let it run for 1-2 minutes and stop. Depress the brake pedal several times with normal force. If the pedal goes down on the first press, but gradually rises on the second or third press, the brake booster is good. If the pedal height does not change, the booster is faulty.
With the engine off, depress the brake pedal several times and check for a change in pedal height. After that, press the pedal and start the engine. If at the same time the pedal goes down a little, the amplifier is working. If the pedal height remains the same, the booster is defective.
With the engine running, depress the brake pedal and stop the engine. Keep the brake pedal depressed for 30 seconds. If during this time the pedal height does not change, the amplifier is working. If the pedal rises, the amplifier is faulty.
If a malfunction was determined during one of the indicated test methods, check the vacuum hose and booster, eliminate the malfunctions. If the results of all checks are positive, the amplifier is working.
Checking the operation of the check valve of the vacuum brake booster
Check on the non-return valve installed in the vacuum hose.
Vacuum brake booster: 1 - vacuum brake booster; 2 - pressure regulator (on vehicles without ABS); 3 – brake pipelines; 4 - vacuum hose
Remove the brake booster vacuum hose.
Note. The non-return valve is installed with an interference fit in the vacuum hose according to the alignment marks.
Check the operation of the check valve with a vacuum pump.
Attention! If the non-return valve is defective, replace it with the vacuum hose assembly.
Removal of air from a hydraulic drive of brakes (pumping)
Hydraulic brake reservoir
Remove the brake fluid reservoir cap and add brake fluid (figure 6.4).
Attention! If brake fluid comes into contact with the paintwork of the body, wash it off immediately.
Note. When removing air from the hydraulic drive under pressure, do not press the brake pedal.
Bleeding hydraulic brakes
Attach a vinyl hose to the bleeder on the wheel cylinder, dip the other end of the hose into a container of brake fluid.
Press the brake pedal several times.
With the pedal fully depressed, loosen the bleeder screw until brake fluid starts to flow through the hose, then tighten the bleed screw.
Repeat the above steps until there are no air bubbles in the fluid flowing out of the brake cylinder.
Tighten the bleed screw.
The moment of an inhaling of unions of prorolling 7–13 Н·м.
Perform the indicated operations on the remaining wheel cylinders in the following order: rear right wheel (in the direction of the vehicle), front left wheel, rear left wheel, front right wheel.
Adjustment of the lever of a drive of parking brake system
After pumping the hydraulic drive of the brakes, press the brake pedal 20 times with a force of more than 10 kgf.
Tighten the parking brake lever more than three times to failure.
Parking brake lever: 1 – parking brake lever; 2 - adjusting nut; 3 – a cable of a drive of a parking brake; 4 - equalizer; 5 - casing
When lifting, the lever should move 6-8 teeth of the sector (the point of application of force should be located at a distance of 25 mm from the end of the lever). When moving more or less sector teeth, adjust the stroke of the lever.
The parking brake control lamp goes out when the brake is fully released and lights up when the lever is raised by one sector tooth. If the switch does not operate as specified, replace it.
After completing the adjustment, make sure that there is no braking of the rear wheels with the parking brake lever fully lowered.