Acura 01469-SEP-A00 Power Brake Booster

In addition to the specified intervals, the brakes should be inspected every time the wheels are removed or whenever a defect is suspected. Any of the following symptoms could indicate a potential brake system defect: The vehicle pulls to one side when the brake pedal is depressed; the brakes make squealing or dragging noises when applied: brake pedal travel is excessive; the pedal pulsates; or brake fluid leaks, usually onto the inside of the tire or wheel. Disc brakes can be visually checked without removing any parts except the wheels. Remove the hub caps (if applicable) and loosen the wheel lug nuts a quarter turn each. Raise the vehicle and place it securely on jackstands. Remove the wheels. Now visible is the disc brake caliper which contains the pads. There is an outer brake pad and an inner pad. Both must be checked for wear. Measure the thickness of the outer pad at each end of the caliper and the inner pad through the inspection hole in the caliper body. If any brake pad thickness is less than specified, then all brake pads must be replaced. If you're in doubt as to the exact pad thickness or quality, remove them for measurement and further inspection. Check the disc for score marks, wear and burned spots. If any of these conditions exist, the disc should be removed for servicing or replacement. Before installing the wheels, check all the brake lines and hoses for damage, wear, deformation, cracks, corrosion, leakage, bends and twists, particularly in the vicinity of the rubber hoses and calipers. Install the wheels, lower the vehicle and tighten the wheel lug nuts. Sit in the driver's seat and perform the following sequence of tests. With the brake fully depressed, start the engine - the pedal should move down a little when the engine starts. With the engine running, depress the brake pedal several times - the travel distance should not change. Depress the brake, stop the engine and hold the pedal in for about 30 seconds - the pedal should neither sink nor rise. Restart the engine, run it for about a minute and turn it off. Then firmly depress the brake several times - the pedal travel should decrease with each application. If your brakes do not operate as described, the brake booster has failed.

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 airtightness 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. Disassembly of the power unit requires special tools and is not ordinarily performed by the home mechanic; if a problem develops, it's recommended that a new or factory rebuilt unit be installed. To remove the booster, first remove the brake master cylinder, then disconnect the hose leading from the engine to the booster, being careful not to damage the hose. For 2003 and earlier models, remove the two mounting bolts for the bracket that secures the fuel line above the booster, the starter cable retainer, and the mounting bolt for the bracket that secures the windshield wiper relay above the booster. For 2004 and later models, remove the air filter housing and detach the brake lines from the clip against the firewall. Working inside the vehicle, locate the pushrod clevis pin connecting the booster to the brake pedal and remove the lock-pin and clevis pin to disconnect the pushrod from the pedal, then remove the four booster mounting nuts holding the brake booster to the firewall. Working outside the vehicle, carefully guide the booster out until the studs and pushrod clevis clear the holes in the firewall, then remove the booster from the engine compartment, taking care not to bend any brake lines or damage the booster studs. If a new power brake booster unit is being installed, measure the length of the pushrod from the center of the clevis hole to the booster's mounting surface, including the gasket in the measurement, and compare it with the required value. Check and adjust the booster pushrod-to-master cylinder clearance to avoid brake drag or excessive brake pedal travel. Using a hand-held vacuum pump, apply a vacuum of 30 in-Hg to the booster and measure the pushrod protrusion from the master cylinder mounting surface, then measure the distance from the mounting flange to the end of the master cylinder and from the end of the master cylinder to the bottom of the pocket in the piston. Subtract the measurements to determine the pushrod clearance, which should be zero; adjust the pushrod length as necessary. For 2004 and later models, install the booster, tighten the retaining nuts, and connect the pushrod to the brake pedal using a new lock-pin. Install the master cylinder and brake hoses and lines, adjust the brake pedal freeplay, and bleed the brakes. The remainder of the installation is the reverse of removal, ensuring to tighten the booster mounting nuts and use a new lock-pin for the clevis pin. Finally, check and adjust the brake pedal height and carefully test the operation of the brakes before placing the vehicle into normal service.

To remove the brake master cylinder, start by taking off all engine and cowl covers as equipped, followed by the strut brace. For models from 2004 and later, remove the mounting bolts for the fuse/relay box in the engine compartment and set it aside. Disconnect the electrical connector for the fluid level sensor and use a syringe to extract as much fluid as possible from the reservoir. Place rags under the fluid fittings and prepare caps or plastic bags to cover the ends of the lines after disconnection, taking care to avoid spilling brake fluid, which can damage paint. Use a flare nut wrench to loosen the fittings at the ends of the brake lines where they enter the brake master cylinder, then pull the brake lines slightly away and plug the ends. Remove the brake master cylinder mounting nuts and carefully pull the brake master cylinder off the studs, ensuring no fluid spills. If installing a new brake master cylinder, transfer the reservoir from the old one, using new seals as needed. Before installation, bench bleed the new brake master cylinder by clamping it in a vise and attaching bleeder tubes to the outlet ports, filling the reservoir with the recommended brake fluid. Slowly push the pistons into the brake master cylinder to expel air, repeating until no bubbles are present. After removing the bleed tubes, install plugs in the open ports and the reservoir cap. Install a new rod seal onto the brake master cylinder, applying silicone grease, and then mount the brake master cylinder over the studs on the power brake booster, tightening the nuts only finger tight initially. For older models, measure the distance from the piston pocket to the end of the brake master cylinder on both the old and new units. Thread the brake line fittings into the brake master cylinder, ensuring they are tightened without stripping the threads. Fully tighten the mounting nuts and brake line fittings, then fill the reservoir with fluid and bleed the brake master cylinder and brake system by having an assistant depress the brake pedal while loosening the fittings to allow air and fluid to escape. After completing the bleeding procedure, rinse the area under the brake master cylinder with clean water to prevent damage from brake fluid. Finally, the remainder of the installation follows the reverse order of removal, and it is crucial to test the operation of the brake system before returning the vehicle to normal service.