Bleeding Car Brakes
Whenever a line is disconnected from any wheel, it is necessary that the wheel cylinder be bled. If the hydraulic line is disconnected from the master cylinder or the brakepedal has a spongy feeling, each wheel cylinder must be bled to expel air from the system.
- Home Repair Tips -
Brake Servicing :
Begin at the corner furthest from the driver and proceed in order toward the driver. (Right rear, left rear, right front, left front.)
Locate the bleeder screw at the rear of the caliper body (or drum brake wheel cylinder.) Remove the rubber cap from the bleeder screw and dont lose it!
Place the box-end wrench over the bleeder screw (10mm for discs, 8mm for drums.) An offset wrench works best since it allows the most room for movement. (If you do not have an offset wrench, avoid pushing the wrench head to the bottom of the bleeder screw since the wrench may interfere with other parts during movement. Allow a standard wrench to sit near the top of the bleeder screw contact point.)
Place one end of the plastic hose over the nipple of the bleeder screw.
Place the other end of the hose into the disposable bottle.
Place the bottle for waste fluid on top of the caliper body or drum unit. Hold the bottle with one hand and grasp the wrench with the other hand.
Instruct the assistant to "apply." The assistant should pump the brake pedal three times, hold the pedal down firmly, and respond with "applied." Instruct the assistant not to release the brakes until told to do so.
Loosen the bleeder screw with a brief Ό turn to release fluid into the waste line. The screw only needs to be open for one second or less. (The brake pedal will "fall" to the floor as the bleeder screw is opened. Instruct the assistant in advance not to release the brakes until instructed to do so.)
Close the bleeder screw by tightening it.
Instruct the assistant to "release" the brakes. Note: Do NOT release the brake pedal while the bleeder screw is open, as this will suck air back into the system!
The assistant should respond with "released."
Inspect the fluid within the waste line for air bubbles.
Continue the bleeding process (steps 11 through 16) until air bubbles are no longer present. Be sure to check the brake fluid level in the reservoir after bleeding each wheel! Add fluid as necessary to keep the level above the seam line. (Typically we repeat this process 5-10 times per wheel when doing a standard bleed.)
Move systematically toward the driver right rear, left rear, right front, left front - repeating the bleeding process at each corner. Be sure to keep a watchful eye on the brake fluid reservior! Keep it full!
When all four corners have been bled, spray the bleeder screw (and any other parts that were moistened with spilled or dripped brake fluid) with brake cleaner and wipe dry with a clean rag. (Leaving the area clean and dry will make it easier to spot leaks through visual inspection later!) Try to avoid spraying the brake cleaner DIRECTLY on any parts made of rubber or plastic, as the cleaner can make these parts brittle after repeated exposure.
Test the brake pedal for a firm feel. (Bleeding the brakes will not necessarily cure a "soft" or "mushy" pedal since pad taper and compliance elsewhere within the system can contribute to a soft pedal. But the pedal should not be any worse than it was prior to the bleeding procedure!)
Be sure to inspect the bleeder screws and other fittings for signs of leakage. Correct as necessary.
Properly dispose of the used waste fluid as you would dispose of used motor oil. Important: used brake fluid should NEVER be poured back into the master cylinder reservoir! Dispose of the fluid as you would motor oil.
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