Chevrolet 25878055 Brake Booster

Brakes should be checked either when the wheels have been taken off or if there are signs that something could be wrong; these are whereby the vehicle pulls to the side on application of brakes, squealing or dragging noises, excessive travel of the pedals and pulsating or soft pedals, or if there are signs of brake fluid leakage. Disc brakes can be checked visually by simply removing station hub caps, loosening the wheel lug nuts while the car is on the ground but securely lifted using a jack and two jackstands-then by removing the wheels to get access to the disc brake caliper & pads. The thickness of outer and inner pads must be measured and compared with the indicated values; if, for example, one of the values is less, all the pads must be replaced. There should be inspection of the disc for score marks, wear and burned spots and if there is an indication of a problem, then servoing or replacement is needed. Before the wheels can be reinstalled all the brake lines and hoses should be checked for signs of damages of wear. When wheels have been fixed and the car dropped to the ground, the lug nuts should be tightened to the right level of torque. For the brake booster check, the brake should be fully depressed with the key set in the starting position and seated in the driver's seat: the pedal should move slightly when the engine is started. While the engine is running the brake pedal must not alter in distance travelled after several depressions. Again, after switching off the engine, pressing the pedal for about 30 seconds should give no movement. The decrease in pedal travel should occur after the engine is restarted, and the brake is firmly depressed several times; otherwise the failure lies with the brake booster.