To bleed brakes, open each caliper’s bleeder screw in turn, starting with the wheel the manufacturer specifies, usually the one farthest from the master cylinder, and push fluid through until it comes out with no air bubbles, keeping the master cylinder reservoir topped up the whole time. You can do it with a helper pumping the pedal, with a one-person vacuum or pressure bleeder, or by gravity. Bleeding removes air that makes the pedal soft and spongy.
What you need
- Fresh brake fluid of the type printed on the reservoir cap or in the manual (DOT 3, DOT 4 or DOT 5.1 are glycol based; silicone DOT 5 must never be mixed with them)
- A box wrench for the bleeder screws and a length of clear tubing
- A catch bottle, rags and gloves; brake fluid damages paint
- A helper, or a vacuum or pressure bleeder
How to bleed brakes with two people
- Fill the reservoir to the full mark and keep it from running dry.
- Fit the tubing to the first bleeder and put the other end in the bottle with a little fluid in it.
- Have your helper press the pedal and hold it down.
- Open the bleeder a quarter turn, let fluid and air out, then close it before the pedal is released.
- Repeat until clear fluid with no bubbles comes out, then move to the next wheel in the specified order.
- Tighten the bleeders, top up the reservoir and check for a firm pedal before driving.
One-person and gravity bleeding
- Vacuum bleeder: a hand or air-powered pump on the bleeder draws fluid and air through while you watch the reservoir.
- Pressure bleeder: pressurizes the reservoir so fluid pushes through each open bleeder in turn.
- One-way valve tubing: lets you pump the pedal yourself without drawing air back in.
- Gravity: open a bleeder and let fluid drip through slowly; simple, but slow, and most useful for a fluid refresh.
Which order?
The traditional order is right rear, left rear, right front, left front, working from farthest to nearest the master cylinder, but many vehicles with ABS or a diagonal split system specify their own order. Use the sequence in the service manual. Calipers with more than one bleeder are bled as the maker’s instructions describe.
ABS and new parts
Air trapped in the ABS unit may need a scan tool to cycle the valves while bleeding. Always bleed after replacing calipers, hoses or the master cylinder, or after the reservoir has run dry.
How often to change brake fluid
Brake fluid absorbs moisture over time, which lowers its boiling point and can corrode parts. Follow the replacement interval in your owner’s manual, and flush it sooner if it is dark or after heavy towing or track use.
Brake upgrade for heavy-duty GM trucks
For 2013-2025 Chevrolet and GMC 2500 and 3500 trucks, the SSBC-USA B8-Barbarian rear caliper upgrade kit ($2,031.00) replaces the rear calipers with 8-piston calipers machined from billet aluminum. It bolts to the stock axle with OEM hardware, works with the factory hydraulics and ABS, and ships fully assembled with high-friction, low-dust semi-metallic pads; each caliper has four stainless bleeders.
More on brakes: how long do brake pads last and sticking brake caliper symptoms.
More guides: ABS light · drilled vs slotted rotors · brake pedal goes to the floor or feels spongy · rear disc brake conversion · clutch master cylinder symptoms.
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