Brake fault diagnostics
Cause | Method of elimination |
Brake pedal idle travel too long | |
| Friction linings are completely or partially worn out | Replace the brake friction linings. |
| Failure of one of the braking circuits | Check the brake circuits for brake fluid leaks. |
The brake pedal goes far when pressed and is springy | |
| Air in the brake system | Bleed the brakes. |
| Too little brake fluid in the expansion tank | Add new brake fluid. |
| The rear friction brake pads are very worn, the pad base plate is adjacent to the spring | Replace the friction linings. Use genuine friction linings. |
| Formation of steam. Occurs under heavy load, such as when driving on a mountain pass | Replace brake fluid. Bleed air from brakes. |
Smooth brake action, brake pedal must be pressed all the way | |
| Pipeline leakage | Tighten the pipeline connection elements or replace it. |
| Damage to the seal in the master or wheel brake cylinder | Replace the seal. If the seal in the master cylinder is damaged, replace the internal parts or the cylinder itself. |
| Damage to the stationary rubber gasket | Repair the caliper. |
Poor braking effect despite strong pressure on the brake pedal | |
| The friction linings are oiled | Replace friction linings. |
| Friction lining defective or hardened | Replace the friction linings. Use only genuine friction linings. |
| The brake booster is faulty | Check the brake booster. |
| Piston jamming | Ensure free movement of the caliper. |
| Contamination of the hydraulic system | Clean and replace brake fluid. |
| The friction linings are worn out | Replace friction linings. |
The brakes are squeaking | |
| The friction linings are worn out | Replace friction linings. |
| Often a consequence of atmospheric influences (air humidity) | No action is required if the creaking is observed after the car has been parked for a long time in high humidity and does not recur after the first braking. |
| Friction lining defective | Replace the friction linings. Use branded friction linings. Cover the base of the lining with anti-squeak paste. |
| The brake disc rotates not parallel to the caliper | Check the caliper mating surface. |
| Contaminated wells in the support | Clean the caliper wells. |
| Incorrect installation of pistons in the rear wheel calipers | Check the 20 degree piston setting. |
Brakes lock up when braking lightly | |
| Friction linings are not lubricated with oil | Replace friction linings. |
The brake tightens spontaneously | |
| The compensation hole in the master brake cylinder is clogged | Clean the master cylinder and replace the internal parts. |
| Too little clearance between the control rod and the piston of the master brake cylinder | Check the gap (work in a repair shop). |
The friction linings do not separate from the brake disc, the wheels are difficult to turn by hand | |
| Corrosion in the caliper cylinders | Repair the caliper, replace if necessary. |
Uneven wear of the linings | |
| Friction lining defective | Replace brake pads. Use original friction pads. |
| The caliper is dirty | Clean the caliper wells. |
| Tight piston stroke | Check the piston installation. |
| Brake system leak | Check the brake system for leaks. |
Brake pedal pulsation | |
| Too much thickness tolerance or lateral runout of the brake disc | Check runout and tolerance. Rework the brake disc or replace it. |
| The brake disc does not rotate parallel to the caliper | Check the caliper mating surface. |
| Functioning of the anti-lock braking system ABS | Does not require any measures, normal phenomenon |
Brake vibration | |
| Friction lining defective | Replace the friction linings. Use only genuine friction linings. |
| Partial corrosion of the brake disc | Carefully sand the disc with a sanding block. |
| Lateral runout of brake disc | Rework or replace the brake disc. |
The brake pedal drops slowly when pressed lightly | |
| Master brake cylinder malfunction | Replace the master cylinder. |
One-way brake action | |
| The air pressure in the tires does not correspond to the prescribed one | Check tire pressure and adjust. |
| Uneven tire wear | Replace worn tires. |
| The friction linings are oiled | Replace friction linings. |
| Wheel suspension or steering fault | Check it out |
| Different types of pads on one axis | Replace the friction linings. Use original linings. |
| Poor contact of friction linings | Replace friction linings. |
| The pipeline is clogged | Check the brake pressure of all four brakes. |
| Contaminated caliper wells | Clean the seating surface and guide surfaces of the friction linings in the caliper. |
| Corrosion in the caliper cylinders | Replace the caliper. |
| Uneven wear of friction linings | Replace friction linings (both wheels). |
The brakes get hot while driving | |
| The compensation hole in the master brake cylinder is clogged | Clean the master cylinder and replace the internal parts. |
| Poor idle stroke of the master cylinder pushrod | Check for sufficient clearance between the pedal and the pushrod and adjust if necessary. |
| Brake piston is stuck or stiff | Restore patency. |
| The brake line is clogged | Clean the pipes, replace the brake fluid. |
| Incorrect parking brake adjustment | Adjust correctly. |