How to Bleed Air from Car Brakes?

[LaMackenzie]

The sequence for bleeding air should follow the order of right rear wheel, left rear wheel, right front wheel, left front wheel, and then the clutch master cylinder. Locate the bleeder screw on the brake caliper, remove the dust cap from the bleeder valve, and connect the bleeder port to a drain bottle using a rubber tube. First, press the brake pedal continuously 5 to 6 times, then hold it down. Immediately loosen the bleeder screw on the right rear wheel brake caliper and quickly tighten it again. Repeat this process until brake fluid shoots out in a straight line from the bleeder screw.

[LaEli]

Hey bro, bleeding brakes requires teamwork! First, top up the brake fluid reservoir with fresh DOT4 fluid, but don't tighten the cap completely. Connect a transparent hose to the bleed nipple and insert it into an empty bottle. Have your buddy pump the brake pedal about a dozen times until it feels firm, then hold it down. Quickly loosen the bleed screw to let air bubbles escape, right? Tighten the screw immediately once the fluid flows bubble-free. Crucial reminder: follow this sequence - right rear → left rear → right front → left front. After finishing, double-check the reservoir fluid level. Last time I did this, the brake pedal felt noticeably firmer afterwards. Though it's a hassle, it's absolutely vital. If you're unsure, better play it safe and visit a repair shop - safety first!

[HarmonyFitz]

Bleeding the brake system requires proper technique. Prepare a plastic water bottle filled halfway with old brake fluid as a collection container. Attach one end of a clear tube to the bleeder valve and submerge the other end below the fluid surface in the bottle to prevent air backflow. Have someone in the car slowly press the brake pedal all the way down and quickly release it, repeating several times. When the pedal is fully depressed, they should shout 'Open', at which point you immediately loosen the bleeder screw. Once the bubbles in the tube turn into a steady stream of pure fluid, shout 'Close'. Older vehicles' brake lines tend to trap air, so I often need to cycle through this process two or three times to completely purge the system. After finishing, test drive at moderate speed - perform several hard stops at 40 km/h to check if the brake dive feels firm. A spongy pedal indicates remaining air in the system.

[SanSamantha]

Remember to wear gloves throughout the process as brake fluid is highly corrosive. Use an open-end wrench matching the bleeder valve size, typically 10mm or 8mm. Clean the bleeder valve dust before attaching the tube to prevent contaminants from entering the system. The person pumping the brakes should wait 2 seconds between each pedal release to allow fluid to flow back, and coordinate movements with verbal commands during depression. The biggest risk is incomplete air removal or introducing new bubbles, so always use a filter when topping up with new fluid. Once I forgot to test drive after bleeding and nearly rear-ended at the first traffic light - now I always test with three sets of emergency stops before considering the job done.

[LaRebecca]

Using the pressure bleeding method is more labor-saving. Buy a hand-operated pressure bleeding tool, connect it to the oil reservoir, and pressurize it to 0.5Bar. Then, loosen the bleed screws on each wheel one by one, letting the oil flow out with the air. This method doesn't require pumping the brakes and can be done by one person, making it especially suitable for emergency situations during travel. Last time on the Sichuan-Tibet line when the brakes became soft, this method saved me until I reached the repair shop. Be careful not to exceed 0.8Bar when pressurizing, as old brake lines might not withstand it. Once the oil flows without bubbles, immediately tighten the screws. Don't forget to keep topping up the oil reservoir during the process; if it goes below the MIN line, air will get in again, and all the effort will be wasted.

[StElena]

Common pitfalls for beginners: Using the wrong oil causing rubber parts to swell—different DOT grades must never be mixed; failing to perform a bleed test after bleeding, leaving bubbles trapped in the ABS pump; overtightening the drain plug and stripping the threads. My repair shop handles two or three cars daily with bleeding mistakes, the worst case requiring replacement of four brake lines. True professionals connect a diagnostic tool to activate the ABS pump's bleeding procedure—manual bleeding at home removes at most 80% of the air. Last time, a BMW repair required three attempts to fix brake noise due to incomplete electronic parking brake bleeding.