Saturn 15214486 Power Brake Booster ASSEMBLY

In addition to the specified intervals, the brakes should be inspected every time the wheels are removed or whenever a defect is suspected. Symptoms indicating a potential brake system defect include the vehicle pulling to one side when the brake pedal is depressed, squealing or dragging noises when the brakes are applied, excessive brake pedal travel, pulsating of the pedal, or brake fluid leaks, typically onto the inside of the tire or wheel. Begin by loosening the wheel lug nuts, then raise the vehicle and place it securely on jack stands before removing the wheels. Each caliper contains two pads (an outer and an inner), which are visible with the wheels removed. Check the pad thickness by looking at each end of the caliper and through the inspection window in the caliper body; if the lining material is less than the specified thickness, replace the pads. If it is difficult to determine the exact thickness, remove the caliper(s) and pads for further inspection. Clean the pads with brake cleaner and re-measure them, then measure the disc thickness with a micrometer to ensure it has service life remaining; replace any disc thinner than the specified minimum thickness and check for scoring, gouging, or burned spots. Before installing the wheels, inspect all brake lines and hoses for damage, wear, or leakage, and ensure they are clear of sharp edges and moving parts. All models have rear drum brakes; with the rear wheels removed, ensure the parking brake is off and tap on the outside of the brake drums to loosen them before removing the drums. Clean the brake assemblies and note the thickness of the lining material on both front and rear shoes; if any lining is thinner than specified, replace all brake shoes, especially if they are cracked or soaked with brake fluid. Ensure all brake springs are connected and in good condition, check the wheel cylinders for fluid leakage, and inspect hoses and connections for signs of leakage. Wipe the inside of the brake drums with a clean rag and check for score marks or deep scratches; if imperfections cannot be removed, the drum must be machined. If all parts are in good condition, install the drums, wheels, and lower the vehicle. To check the brake booster, sit in the driver's seat and perform a series of tests: with the brake fully depressed, start the engine and observe if the pedal moves down slightly; with the engine running, depress the brake pedal several times to ensure the travel distance does not change; then, with the engine off, hold the pedal for about 30 seconds to check for sinking or rising. Restart the engine, run it for about a minute, and turn it off, then firmly depress the brake several times to see if the pedal travel decreases with each application; if not, the brake booster has failed. For the parking brake, park the vehicle on a steep hill with the parking brake set and the transmission in Neutral; if the parking brake cannot prevent the vehicle from rolling, it requires attention.

To perform an operating check, depress the brake pedal several times with the engine off to ensure there is no change in the pedal reserve distance, then start the engine; if the pedal goes down slightly, operation is normal. For an air tightness check, start the engine and turn it off after one or two minutes, then depress the brake pedal several times slowly; if the pedal goes down farther the first time but gradually rises after the second or third depression, the booster is airtight. While the engine is running, depress the brake pedal and stop the engine with the pedal depressed; if there is no change in the pedal reserve travel after holding the pedal for 30 seconds, the booster is airtight. The power brake booster is not rebuildable and must be replaced if a problem develops. Begin by disconnecting the cable from the negative terminal of the battery, then disconnect the vacuum hose check valve from the power brake booster. Unbolt the under hood electrical center and set it aside, followed by removing the battery and the battery tray assembly. When the engine is completely cool, disconnect the hose from the coolant reservoir and the sensor wiring harness from the master cylinder. Remove the master cylinder mounting nuts, carefully pull it from its studs, and position it aside without disconnecting the brake lines. Disconnect any wiring harnesses from the booster and, for automatic trans axle-equipped models, move the trans axle control module out of the way. For ABS-equipped models, clean the areas around the ABS module fittings, disconnect the wiring from the module, and place rags under the module to catch any spilled brake fluid. Disconnect all hydraulic lines from the module, making notes of their locations to assist in assembly, and seal all openings to prevent contamination. Loosen the ABS modulator mounting nuts and pull the unit from its bracket, then remove the mounting bracket. For all models, remove the plastic cover from beneath the steering wheel, which is secured by screws and clips, and working under the instrument panel, remove the clip from the brake booster push rod. Remove the foam insulator from the brake pedal assembly, then remove the four brake booster mounting nuts. Pull the brake booster forward and toward the center of the engine compartment to remove it, ensuring to pull out the foam washer if it didn't come out with the booster. Installation is the reverse of removal; before installing the new booster, lubricate the push rod pin on the brake pedal arm with multipurpose grease, connect the push rod to the brake pedal, and install the clip. Finally, bleed the brakes and test the operation of the brakes thoroughly before placing the vehicle into normal service.

Start by depressing the brake pedal several times with the engine off to ensure there is no change in the pedal reserve distance. Next, depress the pedal and start the engine. If the pedal goes down slightly, the operation is normal.