Michigan 3SI Tech/Info Pages

Bleeding The Brakes

"How-To" by Ken Middaugh

NOTE: Before bleeding your brakes, please make sure that you understand all of the steps in the process.  If you have any questions, please email me.  Good luck!

Brake bleeding or slave cylinder bleeding is really easy. It is necessary for a few reasons:

  1. If fluid level gets too low, air bubbles are introduced into the system, air bubbles increase the 'spongy' brake pedal feel or could cause the clutch not to release completely during shifting.
  2. Brake fluid absorbs water over time, water is corrosive to components and lowers the boiling point of the fluid.
  3. fluid becomes dirty.

Bleeding replaces the old, dirty, water-saturated, and air-bubble-ridden fluid with new clean fluid. It should always be done whenever the 'closed' hydraulic system is opened such as a brake job, caliper or slave cylinder rebuild or replacement, hose replacement, etc. It should also be done as preventative maintenance.

On our ABS cars, you're supposed to bleed the brakes with the car running.   The order is (sitting in the drivers seat):  right rear, left front, left rear, right front.

To bleed the clutch slave cylinder, you need to remove the battery & windshield washer fluid bottle.  The slave cylinder is on top of the transmission between the engine and the firewall.

Usually, you need two people to bleed hydraulic systems -- one to open & close the bleed screws, the other to press the pedal. Here are the steps for brakes or clutches:

  1. Attach small hose to the bleed screw on top of brake caliper or slave cylinder, place the other end into a catch container.
  2. Top off fluid in reservoir; brake and clutch reservoirs are always in the engine compartment on the firewall on the drivers side.
  3. Open bleed screw 1/4 to 1/2 turn.
  4. Depress pedal (clutch or brake) all the way to the floor.
  5. Close screw.
  6. Release pedal.
  7. Go back to step 2.

Actually, you don't have to do step 2 with every pedal press. Usually you can go 5 to 10 pedal presses before you have to fill the reservoir. Just be sure to not let the fluid drain completely out since this will introduce air bubbles into the lines; the very reason you're bleeding is to remove the bubbles. Also, empty the catch can often. When the fluid entering the catch can is clean, you can stop repeating the steps and move on to the next caliper.

If you want to do this alone, there are one-person bleeder products available, such as hoses with checkvalves. This means that you can open the bleed screw and not have to close it with each pedal push. Hence, one person can bleed their clutch/brakes unassisted.

My favorite of this type of product is Speedbleeder bleed screws-- I installed them on the brakes & the slave cylinder.