Kia 0K52Y43800A Master Vacuum Assembly

Ensuring regular checks are carried out on a vehicle's brakes is important for safety, especially when the wheels are taken off or any brake faults are suspected. Potential signs of malfunction in a braking system include vehicle drifting away, screeching or dragging sounds from the brakes when applied, too long pedaling, pedal pulsations or fluid leakage. The engine and accessories should be switched off and remember to remove the negative terminal cable connected with battery to prevent accidents before any repairs. The battery should be treated with caution because it produces highly flammable hydrogen gas and its electrolyte contains corrosive sulfuric acid. Indicators showing corrosion and loose connections call for removal of a battery for cleaning purposes. Next step is to clean the battery top as well as cable clamps using a solution of warm water combined with baking soda; rinse thoroughly; make sure that the fasteners of battery tray and hold-down clamp are good. The inspection should also include checking drum linings and disc brake pads, condition of discs as well as other parts such as shoes, springs, adjusters, etc., cleaning them up, measuring components as necessary. When power brake boosters fail tests should be performed while they run and after being turned off by attempting to apply brakes according to specifications given by producers. Lastly one can test if parking brake functions properly by parking on an incline with transmission in neutral select position so that it stops vehicles from rolling down hill.

To perform an operating check, depress the pedal and start the engine; if the pedal goes down slightly, operation is normal. Depress the brake pedal several times with the engine running to ensure no change in the pedal reserve distance. 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 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. The power brake booster unit requires no special maintenance apart from periodic inspection of the vacuum hoses and the case, and it should never be disassembled; if a problem develops, it must be replaced with a new one. Remove any vacuum from the booster by pumping the pedal several times with the engine off until the pedal feels hard to push. For models from 2005 or earlier, remove the battery; for 2006 or later models, remove the air filter housing. Clean the area where the master cylinder attaches to the power brake booster, then detach the master cylinder from the brake booster and carefully move it aside while keeping it supported, ensuring not to disconnect the brake lines. Disconnect the vacuum hose from the check valve located on the outside of the brake booster, then working under the dash, disconnect and remove the brake light switch. Remove the clevis pin retaining clip with pliers and pull out the pin to disconnect the brake pedal pushrod from the top of the brake pedal. Remove the nuts attaching the booster to the firewall, then carefully withdraw the brake booster unit from the firewall and out of the engine compartment. Before installing the new booster, measure the booster pushrod-to-master cylinder piston clearance for 2005 and earlier models or booster input rod length for 2006 and later models, adjusting as necessary. To install the booster, place it into position on the firewall, tighten the retaining nuts to the specified torque, and connect the brake pedal to the brake booster pushrod with the clevis pin, securing it with the retaining clip. Installation is the reverse of removal, using a new gasket between the booster and the firewall. For 2005 and earlier models, if a new power brake booster unit is being installed, use a hand-held vacuum pump to apply a vacuum of 19.7 in-Hg to the booster, measure the pushrod protrusion from the master cylinder mounting surface, and calculate the pushrod clearance by comparing the measurements. For 2006 and later models, measure the distance between the power brake booster and the hole in the input rod clevis, adjusting the clevis length as necessary before installing the booster and connecting it to the brake pedal.