Diagnostics and troubleshooting of the brake system (Mercedes-Benz E-Class W124)

Attention! Before determining a fault in the brake system, check the front wheel alignment angles, tire condition and tire pressure. If there are faults in the anti-lock braking system, the system must be repaired at a service station.

When braking, the car pulls to the side

• Oil got on the brake pads on one side of the car.
• The piston is completely or partially jammed in the caliper.
• Brake pads with different friction materials are used on different sides of the vehicle.
• The caliper mounting bolts are loose.
• Steering or suspension components are worn or damaged.

Brake noise when braking

• The brake shoe friction lining is completely worn out.
• Severe corrosion of the brake disc (may occur if the vehicle has not been used for a long time).
• A stone got into the gap between the brake disc and the brake shield.

Brake pedal travel too long

• The master brake cylinder is faulty.
• There is air in the hydraulic brake system.
• The brake booster is faulty.

Pedal softness when braking

• Damage to rubber hoses of the brake system.
• The master brake cylinder mount is loose.
• The master brake cylinder is faulty.
• There is air in the hydraulic brake system.

When pressing the brake pedal, you need to apply significant force

• The brake booster is faulty.
• The brake booster vacuum hose is disconnected or damaged.
• Damage in one of the circuits of the hydraulic brake system.
• The caliper piston is jammed.
• The brake pads are not installed correctly.
• The brake pads installed are not the correct type.
• The brake shoe linings are dirty.
• On models with diesel engines, the vacuum pump is faulty.

The appearance of strong vibration when braking on the brake pedal or steering wheel

• Severe wear or warping of brake discs.
• Complete wear of brake shoe linings.
• The caliper mounting bolts are loose.
• Steering or suspension components are not securely fastened.

Constant braking of wheels

• The piston in the brake caliper is jammed.
• The parking brake is not adjusted correctly.
• The master brake cylinder is faulty.

Rear wheel locking under moderate braking

• The rear brake pads are dirty.
• The rear brake discs are warped.