By January 5, 2012 Read More →

How to drain a slave cylinder

The slave cylinder is part of the hydraulic clutch manual transmission vehicles. When the master cylinder or the slave cylinder began to leak fluid, it must be replaced by the brake fluid. Adding new fluid will introduce air into the system, creating a soft or nonexistent when clutch pedal is depressed. To purge air from the hydraulic clutch system, you must release the air from the slave cylinder. The following article describes the three ways to drain a slave cylinder.

1. Drain manually secondary cylinder

  • Lift the end of the motor vehicle with two jack stands to gain access to the drain valve, also called the “Pitcock”.
  • Have an assistant sit in the car and press the clutch to the bottom
  • Slide under the vehicle and locate the slave cylinder . It is located inside the transmission on some vehicles and out of the transmission in others. Look in your owner’s manual of your vehicle if you need help locating the slave cylinder.
  • Loosen the drain valve with a wrench and have a container ready to catch the brake fluid to leak.
  • Tighten the valve once it seems that all air is out.
  • Release the clutch pedal . It is likely to stay on the bottom and have to throw it out.
  • Repeat pressing the clutch to the bottom, opening the drain valve to purge air and closing the clutch to feel normal again.
  • Check the brake fluid is at the right level and add more if necessary.

2. Drain a slave cylinder with a vacuum pump.

  • Get a manual vacuum pump at your local auto parts
  • Raise the vehicle with jack stands to access the drain valve
  • Have an assistant sit in the car and press the clutch to the bottom
  • Loosen the drain valve and put the vacuum pump
  • Pump the brake fluid in a container until bubbly air
  • Close the drain valve
  • Pull the clutch pedal up, sending brake fluid to the slave cylinder, and try playing with the pedal . If it feels soft, drain more air.
  • Check the brake fluid is at the right level and add more if necessary .

3. Drain a slave cylinder with a hose

Get a hose or a thin plastic tube in your home or auto parts store of your pets

Raise the vehicle with a jack stand .

Put one end of the hose into the drain valve and insert the other end into a container half full with new brake fluid .

Have an assistant to press the clutch pedal to the bottom, while you loosen the screw on the slave cylinder . The air will flow into the container making bubbles in the brake fluid, making it impossible to re-enter the slave cylinder.

Tighten the screw of the cylinder and then ask the assistant to release the clutch pedal .

Repeat the process until no more bubbles are formed in the container .

Check the brake fluid is at the right level and add more if necessary .

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