How to Bleed the Clutch on a Car

by Don Bowman

A hydraulic clutch consists of a brake fluid reservoir, a master cylinder and a hydraulic brake servo called a slave cylinder. On most cars, the slave cylinder is located on the outside of the transmission, but on some it is located in the bellhousing and is shaped like a bellows. In any event when the clutch is pushed, fluid under pressure travels from the master cylinder to the slave cylinder, which pushes a rod outward and applies pressure to the throwout bearing arm and disengages the clutch. Note that if a clutch is replaced and the flywheel turned, the hydraulic slave cylinder is not likely to have enough travel to properly disengage the clutch. It could ruin your day when the job is complete and it doesn't work. The hydraulic slave cylinder only moves so much and is not adjustable like non-hydraulic models. Taking just a few thousandths off does not seem like enough to make a difference, but it makes a huge difference. If the flywheel is scored up, replace it and the slave cylinder.

Step 1

Raise and support the front of the vehicle with jack stands. Check the clutch reservoir and make sure it is full of fluid. Loosen the bleeder screw on the slave cylinder and let it gravity-bleed to start with. When it has a steady drip, close the bleeder screw.

Step 2

Push the clutch in and out several times and feel the pressure. If the clutch feels good start the car and see if it will go into gear. If it does, it is finished. If it does not go into gear, then a helper is needed to push the clutch.

Step 3

Fill the clutch reservoir as needed and loosen the bleeder screw once more. Have the helper push the clutch down one time to the floor and do not let it up until he is told to do so. Once he says the clutch is to the floor, close the bleeder screw. Have the helper pump the pedal five or six times and leave it all the way up.

Step 4

Repeat Step 3. If the pedal is left up with the bleeder open, it will suck in air and complicate things. Do this several times, checking the fluid level in between until the clutch goes properly into gear and all the air is exhausted.

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