Clutch Slave Cylinder
Found in manual transmission vehicles, the clutch slave cylinder transmits mechanical force from the clutch pedal to the clutch plate without using complicated rods and levers. In order to do this task, this cylinder is filled with brake fluid. However, over time, the fluid inside will leak out. You'll know you need to bleed and replace the slave cylinder if the clutch pedal feels spongy and soft. Your only option to fix this problem is to replace the seals and refill the brake liquid. Unfortunately, more air will get inside once you replace the liquid. To get the air out, you need to bleed the clutch slave cylinder. Here's how:
What you'll need:
- Hose or vacuum pump
- Brake fluid
- An assistant
Step 1: Locate the bleeder valve.
Also referred to as the bleed nipple or petcock, the bleeder valve can be easily seen once the vehicle is securely jacked up on jack stands.
Step 2: Let your assistant step on the clutch pedal.
In order to bleed a clutch slave cylinder, you'll need the help of an assistant because you need someone to step on the pedal while you're under the vehicle.
Step 3: Locate the slave cylinder.
While your assistant is stepping on the clutch pedal, get under the vehicle and locate the cylinder. This component is attached either on the inside or outside of the transmission and is usually mounted with bolts.
Step 4: Loosen the bleed nipple or valve to let air bleed out.
Once you've located the cylinder, you can now let the air bleed out. Depending on the technique you wish to use, you can bleed the cylinder by doing it manually, by using a hose, or by attaching a vacuum pump.
Manual - If you want to do it manually, use a wrench to loosen the bleed valve. Make sure a container is placed underneath to catch the brake fluid. Let the air out and tighten the valve after a few minutes. Let your assistant alternately release the pedal and see if it's still feels spongy. If it does, open the valve again to let the air out and tighten it again after a few minutes. Repeat this process until the clutch doesn't feel spongy anymore.
Using a hose - If you're using a hose, open the bleeder valve and attach the hose. Put one end of the hose in a container that's half-filled with new brake fluid. Then let your assistant step on the pedal as you loosen the cylinder's bleed screw. This will allow the air to flow out of the clutch slave cylinder and into the container. You'll know the air is out if you see bubbles on the brake fluid inside the container. Tighten the bleed screw and ask your assistant to release the pedal. Repeat the process until you don't see new bubbles on the liquid's surface.
Using a vacuum pump - Ask your assistant to step on the pedal while you loosen the bleeder valve and attach the vacuum pump. With a container underneath, pump the brake fluid into the container until you don't see bubbles anymore. Then close the valve. Ask your assistant to release the pedal and see if it still feels soft. If it does, you need to pump out more air.
Step 5: Check the brake fluid level.
Once you've successfully removed air from the clutch slave cylinder, check the reservoir and see if there's enough brake fluid. Add more fluid if the amount is below the acceptable level.