798646e1

2.14. Diagnostics of malfunctions of the brake system

The brake pedal is excessively hardly squeezed out

Brake shoes (disk brake mechanisms), or frictional overlays of boots (drum brake mechanisms) not of that type are established. Check, make replacement.

Passability of the brake line going from the main brake cylinder (MBC) is broken. Check lines, remove the cause of blocking, or make replacement.

The axis of a brake pedal is jammed. Execute necessary repair, or replace an axial bolt and plugs.

The piston of the wheel cylinder / support is jammed. Execute capital repairs of a cylinder/support.

Functioning of the vacuum amplifier of brakes is broken. Check serviceability of the amplifier (see the Head the Brake system).

"Prikhvatyvaniye" of brakes takes place

Passability of GTTs unions is broken. Check, clean GTTs and the tank of brake fluid.

The piston of the wheel cylinder / support is jammed. Execute necessary repair.

The cable of the drive of the parking brake is jammed. Replace a cable.

Are broken, or coupling springs of boots of the drum brake mechanism are extended. Replace defective springs.

Adjustment of pushers of the vacuum amplifier / GTTs is broken. Check, make necessary adjustments.

For identification of signs of a prikhvatyvaniye of brakes the car also establish to a poddomkratta it on props. Serially rotating wheels manually whether check brakes are taken. If all wheels rotate freely, ask the assistant to squeeze out and release a pedal of a foot brake. Make sure that brake mechanisms "release" wheels without delay. Violation of passability of the GTTs union causes a simultaneous prikhvatyvaniye of two wheels which brake mechanisms are switched on in the corresponding concrete hydraulic contour. Release the pumping gate on one of the taken wheels, having made sure that increase in pressure in a contour is the reason of a prikhvatyvaniye.
Jamming of a driving cable of the parking brake usually conducts to a prikhvatyvaniye of the back driveshaft. For check a car back also establish to a poddomkratta it on props, disconnect a driving cable from the executive lever, - the back driveshaft has to begin to rotate freely.

The noise published by brake mechanisms take place

Braking is followed by squeal. Zapolirovan material of frictional slips. Take off the suspected blocks/boots (see an accompanying illustration) and remove polishing from their surface by means of an emery paper.
Braking is followed by a gnash. Material of frictional slips is worn-out. Check a condition of blocks/boots and disks/drums of the suspected brake mechanisms. Replace worn-out blocks / boots, give to a pro-point the damaged disk/reel (see an accompanying illustration).

Squeal of brakes in most cases is caused by a zapolirovyvaniye to gloss of surfaces of frictional overlays of brake shoes, however it is not necessary to lose sight also such possible reasons as use of blocks of improper type, and also loss of antivizgovy springs or protivoskripny slips.
If wear of frictional overlays of blocks/boots to substrate metal takes place, all four blocks / a boot are subject to replacement even if on an opposite wheel they are in good repair.
At a strong istsarapyvaniye of a brake disk / reel it should be pierced or replaced for restoration of efficiency of braking.

Low "softness" of the course of a brake pedal takes place

The automatic regulator of brake mechanisms of back wheels failed. Make necessary repair, or replace the regulator.

Level of brake fluid fell. Check system for existence of signs of leaks, - attentively examine all nipple connections (see an accompanying illustration). Execute necessary repair, restore the level of liquid and pump over hydraulic system.

Air got to hydraulic system. Pump over system.

In most cases "softness" of the course of a brake pedal is connected with hit in hydraulic system of air. Surely it is necessary to find a source of penetration of air and to eliminate the defect taking place (consolidation or nipple connection). Then the system should be pumped over.
It is easy to determine defective components of the brake system by existence on their surface of traces of leak of brake fluid. When braking there is a blocking of wheels

The zasalivaniye of frictional overlays of blocks/boots owing to hit on them of oil or brake fluid takes place. Establish and eliminate the reason of pollution, replace blocks/boots.

The brake drum is deformed. Check, make necessary replacements.

Blocks/overlays of boots not of that type are established. Check, make replacement.

Coupling springs of brake boots are broken or extended. Check, replace defective springs.

The valve of adjustment of pressure is faulty. Replace the valve.

Remove all wheels and, estimate degree of wear of frictional slips and check them for existence of signs of pollution by oil. Check a condition of coupling springs of brake boots, having compared their free length to that for new springs.
Sign of deformation of the brake drum is the pulsation of a brake pedal at easy braking.
If back wheels are constantly blocked, it is necessary to check serviceability of the regulator of pressure.

Pedal pulsations take place during braking

The brake drum / disk is deformed. Pierce a defective component.

Stupichny bearings of forward or back wheels are worn-out, or their pretightness weakened. Execute adjustment of a pretightness, or replace defective bearings.

The deformed brake drums / disks are subject to a pro-point. This work should be charged to experts of a workshop of car service who will also help you to define expediency of this procedure. Perhaps it is necessary to get new components.

"Withering" of brakes takes place

There was a zasalivaniye of frictional overlays of blocks/boots owing to hit on them of oil or brake fluid. Establish and eliminate the reason of pollution, replace blocks/boots.

The brake drum is deformed. Check, make necessary replacements.

The automatic regulator of the back brake mechanism failed. Execute necessary repair of the regulator.

Blocks/boots not of that type are established. Make replacement.

Brake fluid is polluted. Empty hydraulic system and fill in fresh brake fluid. Pump over brakes.

In most cases withering of brakes happens owing to performance of the sharp and frequent braking conducting to a warming up of frictional slips and disks/drums of brake mechanisms. After an ostuzheniye of mechanisms braking has to return to normal.

There is an overheat of brake mechanisms

The automatic regulator of the brake mechanism of a back wheel failed. Execute necessary repair.

Coupling springs of brake boots are broken or extended. Check, replace defective springs.

Adjustment of pushers of the vacuum amplifier / GTTs is broken. Check, make necessary adjustments.

The piston of the wheel cylinder / support is jammed. Execute necessary repair.

It is damaged or blocked a hose/tube of the hydraulic brake line (see an accompanying illustration). Remove the cause of blocking, or replace a defective hose / tube.

The GTTs union is blocked. Check, clean the cylinder and the tank of brake fluid.

Braking is too sharply carried out. Change a driving manner.

To check brake mechanisms for jamming to a poddomkratta the car and establish it on props. Serially rotate each of wheels hands. If the piston wheel hurrah / a support of one of brake mechanisms is jammed, it makes sense to check and make recovery repair of all cylinders / supports, and also GTTs.

There was a refusal of brakes

GTTs failed. Remove the cylinder, execute its recovery repair, pump over hydraulic system.

Level of brake fluid owing to leakages of supports / wheel cylinders fell. Execute necessary repair, pump over hydraulic system.

Level of liquid fell owing to leakages of brake hoses / tubes. Replace defective components, pump over hydraulic system.

Air got to hydraulic system. Find out and remove the cause, pump over system.

Brake fluid is polluted. Empty system, fill in fresh liquid, pump over brakes.

For search of sources of leaks fill in GTTs with brake fluid and ask the assistant to shake a pedal of a foot brake. At the same time try to register external leak of liquid visually.