Chevrolet 89040285 Power Brake Booster Assembly

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Start the engine and turn it off after one or two minutes. Slowly depress the brake pedal several times and observe if the pedal goes down farther the first time but gradually rises after the second or third depression, indicating an airtight booster.

To perform an operating check on the brake booster, start the engine and depress the pedal. If the pedal goes down slightly, the operation is normal. Next, depress the brake pedal several times with the engine running and ensure that there is no change in the pedal reserve distance. For an air tightness check, start the engine and turn it off after one or two minutes. Slowly depress the brake pedal several times and observe if the pedal goes down farther the first time but gradually rises after the second or third depression, indicating an airtight booster. Additionally, depress the brake pedal while the engine is running and then 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. To remove the brake booster, disable the airbag system and disconnect the battery. Detach the vacuum hose and remove the master cylinder. Then, remove the left side under-dash panel and the retaining clip securing the booster rod to the pedal. Remove the four nuts holding the brake booster to the firewall and slide the booster straight out until the studs clear the holes. Finally, pull the booster and gasket from the engine compartment. For installation, reverse the removal steps, using a new gasket and tightening the booster and master cylinder mounting nuts to the specified torque.