How to check the brakes in a car
Content
- Increased free travel of the brake pedal.
Normally, with the engine turned off, it should be 3-5 mm. - The pedal falls or springs.
There may be air in the hydraulic system that needs to be removed. You also need to check the integrity of the hoses and the level of the brake fluid. - The pedal is too hard.
Most likely the cause is a faulty vacuum booster or a damaged hose connecting it to the engine intake manifold. It is also possible that the valve in the booster is stuck. - The car pulls to the side when braking.
It could be damage, uneven wear, or oily brake pads. Other possible causes are leakage of brake fluid in the working cylinder, contamination or wear of the caliper. - Knocking in the brakes.
Knocking can cause problems in the suspension, steering or other components. If we talk about the brake system, then it often occurs due to deformation of the brake disc or corrosion of its working surface. Knocking may also occur due to caliper play caused by wear on the guide seats. In addition, the piston in the cylinder can wedge. - Screeching or screeching when braking.
As a rule, this indicates wear or severe contamination of the brake pads. Damage to the surface of the brake disc is also possible.
What faulty brakes can lead to is clear even to the most inexperienced motorist. It is better to identify and eliminate problems in advance, rather than waiting until they cause serious consequences. Do not miss the moment will allow regular prevention of the brake system. Some signs directly during operation will also help to understand that something is wrong with the brakes.
What should alert
Diagnostics on your own
Not always problems with the brake system are manifested quite clearly. To prevent the brakes from failing at the most inopportune moment, it is important to regularly inspect the system and fix the identified problems.
Brake fluid.
Make sure the brake fluid level in the reservoir is between the Min and Max marks. The liquid should not have a burning smell.
ABS system.
If the machine is equipped with an anti-lock braking system, check its operation. When starting the engine, the ABS indicator should come on and then go off quickly. This means that the ABS system has been tested and is working. If the indicator remains on or, conversely, does not light up, the anti-lock braking system may be faulty.
Checking the tightness of the system.
Make several consecutive presses on the brake pedal. She shouldn't fail. If everything is in order with tightness, then with each press the pedal will become tighter.
Vacuum amplifier.
Start the engine and let it run for five minutes at idle. Then turn off the engine and depress the brake pedal fully. Release and squeeze again. If the vacuum booster is in order, there will be no difference between pressings. If the pedal travel decreases, then this will mean that when you press it again, the vacuum did not form. If in doubt, another test can be performed.
With the engine off, successively press the pedal 5-7 times, then squeeze it to the limit and start the engine. During normal operation of the amplifier, a vacuum will occur in it, and as a result, the pedal will sag a little more. If the pedal remains in place, then most likely the vacuum booster is not in order.
A defective amplifier must be replaced. However, more often damage occurs in the hose connecting the amplifier and the intake manifold. A malfunction may be accompanied by a characteristic hissing sound.
Hoses and working cylinders.
For their inspection, it is better to use a lift or a viewing hole. Hoses must be dry and undamaged. Check for rust on the metal tubes and cylinder body. If there are signs of fluid leakage from the fittings, it is necessary to tighten the clamps and nuts.
Pads and discs.
The need to replace the brake pads will be indicated by the specific rattle of a special metal plate, which is located under the friction lining. When the friction layer is worn away so that the plate is exposed, the metal will rub against the disc during braking, making a characteristic sound. However, it must be borne in mind that not all pads are equipped with such a plate.
Increased brake pedal travel and a longer braking distance can indicate pad wear. Beating and vibration when braking indicate a possible disc distortion.
Sometimes during heavy braking, the pads can stick to the disc due to severe overheating. When you press the brake pedal, and then she does not want to go back, then this is just such a case. If the pad is stuck, you will have to stop, wait until the overheated wheel cools down and remove it, and then try to move the pad away from the disc with a screwdriver.
In winter, the pads may freeze to the disc. This usually happens due to too small a gap between them. Condensation or water from a puddle gets into the gap. As the wheel cools, ice forms.
If the freezing is not strong, then it is possible that you will be able to tear the pads off the disc, smoothly starting off. Do not overdo it, otherwise you can damage the brakes. To solve the problem, you can warm up the discs with hot water (but not boiling water!) or a hair dryer. As a last resort, you can try to blow them with warm air from the exhaust pipe using a rubber hose.
If freezing occurs frequently, it is worth adjusting the clearance between the pad and the disc.
If there are no grounds for an urgent inspection, then it is convenient to combine checking the condition of the brake discs and pads with replacing the wheels.
If the disk is overheated, its surface will have a blue tint. Overheating often causes the disc to warp, so be sure to check its shape.
The surface of the disc must be free of rust, nicks and areas of uneven wear. If there is severe damage, cracks or significant deformation, the disc should be replaced. With moderate wear, you can try to correct the situation by turning.
Make sure the brake disc is thick enough. It can be measured with a caliper and check the readings with the markings on the disk. Often, the disc has marks indicating that it can be erased. A disc worn to these marks must be replaced. Grooving in this situation cannot be a solution to the problem.
Hand brake.
A serviceable handbrake should keep the car on a slope of 23% (this corresponds to a slope of 13 degrees). When you put the car on the handbrake, you should hear 3-4 clicks. If the handbrake does not hold, in most cases it is enough to tighten it with the adjusting nut. If the cable is broken or stretched, it should be replaced. It is possible that the rear brake pads will need to be replaced.
Use of the diagnostic stand.
A more accurate check of the brake system can be carried out using a diagnostic stand. This feature is available in many modern cars. The diagnostic device connects to the on-board computer and, after checking, provides information about existing problems.
