Warning: Check the brake fluid level in the master cylinder reservoir regularly. The brake fluid level should be near the "MAX" mark on the reservoir body.
A drop in the fluid level indicates either a leak in the brake fluid system or excessive wear of the brake pads. If the low brake fluid light comes on in the instrument cluster, do not rush to top it up immediately, first check the thickness of the brake pad linings: maybe it is time to replace the pads?
Car manufacturers recommend changing all brake fluid in the system every 2 years. Some drivers ignore this advice because the fluid in the reservoir seems clean enough to them, and completely in vain. The fact is that brake fluid is very hygroscopic - it absorbs moisture from the air, and this moisture over time not only destroys the surfaces of the brake cylinders, pipes and, as a result, leads to premature failure of the brake system components, but also significantly reduces the boiling point of the brake fluid. The normal boiling point of DOT-4 brake fluids is 230°C. With frequent intensive braking, disc brakes get very hot and with a high water content, the brake fluid can boil, which, as a rule, leads to brake failure.
Helpful advice: In order to avoid unexpected expenses in the future for repairs not only of the brake system, but of the entire car, it is better to replace the fluid in the brake system in a timely manner. We recommend replacing the brake fluid after 2 years.
If you experience problems with your brakes, bleed the brake system (see "Bleeding the brake system". If this does not produce the desired result, the entire brake system must be thoroughly checked as described below (see "Checking the brake system").
Bleeding the brake system
If the brake pedal has become "soft" and becomes "harder" after several consecutive presses, this means that air has entered the hydraulic brake drive.
To remove air from the system, you need to bleed the brakes. The procedure for bleeding the brakes is quite simple, but it is more convenient to do it with an assistant.
A detailed description of bleeding the brake system can be found in Section 9 (see "Replacing brake fluid").
Checking the brake system
1. The reason for the loss of braking efficiency may be poor performance of the vacuum booster. To quickly check it, press the brake pedal several times with the engine off to remove the vacuum in the booster, and then, holding the pedal, start the engine. If the pedal drops slightly after starting the engine, the vacuum booster is working properly.
2. If the pedal remains motionless, check the integrity and reliability of the connection of the vacuum booster hose to the fitting on the engine intake pipe...
3. ...and with the booster. Replace the faulty hose. If the hose is OK, the vacuum booster must be replaced.
Note: The hose is connected to a check valve. Check that the valve is installed correctly and is working properly (see "Checking the operation of the brake booster"). If the check valve is faulty, replace the vacuum booster valve.
If braking is accompanied by beating and pulsation of the brake pedal, you should first check the condition of the front disc brakes.
4. After jacking up the car, remove the front wheels one by one and inspect the brake discs. The thickness of the brake disc should be at least 24.0 mm, the surface of the discs should be even and smooth on both sides. If the surface of the disc is covered with rust in places, which usually happens after a long period of parking of the car with un-dried brakes, try to clean the working surface with a fine emery cloth. If this procedure does not help, you will have to send the discs for grinding or replace them with new ones.
Note: The disc surface wears unevenly. A rim remains on the outer circumference of the disc, so it is more correct to measure the disc thickness with a micrometer.
5. Check the mobility of the brake piston. To do this, try to move the piston with a screwdriver. If the piston cannot be moved, it is jammed in the brake cylinder.
Warning: Jamming of the brake cylinder piston results in constant braking of the corresponding wheel when the pedal is released and skidding of the vehicle when braking.
If braking is accompanied by jerking of the car and creaking in the area of the rear wheels, if the rear of the car skids during intensive braking, check the condition of the brake mechanisms of the rear wheels.
Note: Check the thickness of the disc in the same way as you did for the front brake, the thickness of the brake disc should be at least 10 mm.
Helpful Hint: The parking brake operates the rear brakes via cables that connect the parking brake lever and the brake shoe control mechanisms. Many drivers try to use the parking brake as little as possible to extend its "life", and achieve the opposite result. If you do not use the parking brake, dirt and moisture stagnate in the cable sheaths, the cables become covered with rust, stop moving and break. Therefore, use the parking brake whenever necessary.
(The original article is on the website chevyman.ru)