Too much free travel of the brake pedal
Failure of one of the brake circuits
Check the brake circuits for brake fluid leaks
For drum brakes only:
Sticking of the automatic clearance adjustment device between the pads and the drum
Fix the device sticking.
The brake pedal is pressed down far and springs
Air in the brake system
Remove air from the brake system.
Low brake fluid in the expansion tank
Add brake fluid, bleed the brakes.
Formation of steam bubbles in the brake system. Most often after a heavy load on the brakes, for example, when going downhill
Replace the brake fluid, bleed the brakes.
The braking effect is reduced, the brake pedal is pressed to the stop
Leaky pipeline
Tighten the nuts at the connection points or replace the pipeline.
Damaged seal on the master cylinder or wheel cylinder
Renew the seal. In the master cylinder, replace the internal parts, replace the master cylinder if necessary.
For disc brake only:
The rubber piston sealing ring is damaged
Overhaul the brake caliper.
Poor braking action despite high pedal force
(Publication taken from an online resource: «MercedesMan.ru»)
Oily brake pads
Update your overlays.
Incorrect or hardened brake lining
Update your pads, use only original pads from the vehicle manufacturer.
Brake booster is faulty, booster hose is defective
Check the booster and booster hose.
The brake pads are worn out
Replace the pads.
The brake mechanisms of the wheels do not act simultaneously (the brakes "pull" in one direction)
Tire pressure is not as prescribed
Check the tire pressure and bring it to normal.
Uneven tire wear
Replace worn tires.
Oily brake pads
Update your overlays.
Brake linings of different brands are installed on one bridge
Replace the pads, use only original pads from the vehicle manufacturer.
Poor condition of the working surface of the brake pads
Replace the pads.
For disc brakes only:
Contaminated caliper cavities
Clean the seating and guide surfaces of the brake pads of the caliper.
Corrosion of the wheel brake caliper cylinders
Replace the brake caliper.
Uneven wear of brake pads
Replace the brake pads on both wheels and make sure the calipers move freely.
For drum brakes only:
Heavy stroke of the pistons of the working brake cylinders
Replace the wheel brake cylinders.
The brakes work by themselves
The equalizing hole in the master brake cylinder is clogged
Clean the cylinder and replace its internal parts in a workshop.
The clearance between the drive (rod) and the piston of the master brake cylinder is too small
Check the gap.
Brakes heating up while driving
The brakes work by themselves
Clean the master cylinder and have its internal parts replaced at a workshop.
Difficulty in moving calipers
Lubricate the moving parts of the drum brakes and overhaul the calipers (in the workshop).
Hard running parking brake cables
Lubricate the cable or replace it.
For disc brakes only:
Corrosion of the wheel brake caliper cylinders
Replace the brake caliper.
For drum brakes only:
Weakening of brake shoe tension springs
Replace the springs.
Brake rattling
Incorrect brake pads
Replace the pads. Use only the original pads from the vehicle manufacturer.
For disc brakes only:
The brake disc is covered with corrosion in places
Sand the disc thoroughly.
The brake disc has lateral runout
Modify the disk or replace it.
For drum brakes only:
The brake pads are worn out
Replace the pads. Use only the original pads from the vehicle manufacturer.
Brake drum deformation
Replace the brake drum.
The brake pads do not move away from the brake disc, the wheels are difficult to turn by hand
For disc brakes only:
Corrosion of brake cylinders and brake pads do not come off the brake disc
Overhaul the caliper and replace if necessary.
For drum brakes only:
Brake shoes do not move away from the drum due to breakage of tension springs or their disconnection
Replace the springs.
Uneven wear of the linings
For disc brakes only:
Incorrect brake pads
Replace the pads. Use only the original pads from the vehicle manufacturer.
The caliper is dirty
Clean the caliper cavities.
The caliper is jammed
Spread the guide fingers.
Heavy stroke of wheel cylinder piston
Expand the piston (in the workshop).
Brake system leak
Check the brake system for leaks.
Wedge-shaped wear of brake linings
For disc brakes only:
The brake disc does not rotate parallel to the caliper
Check the caliper mating surface.
Caliper corrosion
Eliminate corrosion and contamination.
Squeaking brakes
Often attributed to atmospheric influences (humidity)
No intervention is required if the brakes squeal after a long period of parking in high humidity, but do not recur after the first braking.
For disc brakes only:
Incorrect brake pads
Replace the pads. Use only the original pads from the vehicle manufacturer.
The brake disc does not rotate parallel to the caliper
Check the caliper mating surface.
The caliper cavities are dirty
Clean the caliper cavities.
For drum brakes only:
Incorrect brake pads
Replace the pads. Use only the original pads from the vehicle manufacturer.
The shoe does not fit tightly
Replace the pads. Use only the original pads from the vehicle manufacturer.
The brake mechanism is dirty
Clean the service brake mechanism.
Weakening or breakage of brake shoe tension springs
Replace the brake shoe tension springs.
Brake pulsation
ABS action
This is a normal phenomenon and does not require intervention.
For disc brakes only:
Lateral runout of the brake disc or too large tolerance on the thickness of the disc
Check the runout and thickness tolerance of the disc. Rework or replace the disc.
The brake disc does not rotate parallel to the caliper
Check the caliper mating surface.
For drum brakes only:
The wheel disc did not fit tightly to the brake drum, which caused the drum to become deformed
You can try to swap the wheels. If necessary, replace the wheel rims.