Hydraulic fluid is poisonous. It also dissolves paint well. Be careful not to let the fluid come into contact with exposed skin or eyes. Keep a rag handy to soak up spills, and if it comes into contact with painted surfaces, rinse immediately with plenty of cold water.
Air in the hydraulic system can cause the clutch to not fully engage when the pedal is depressed. Air can enter the system when any of its components are removed, or if the fluid level in the master cylinder reservoir drops below the acceptable level. Air can also enter the system through holes that are too small for fluid to escape. In this case, the system will require a major overhaul.
To bleed the system, you will need an assistant to press the clutch pedal, a clear plastic container, and a piece of flexible clear tubing that fits the bleeder valve. You can also use a self-bleeding kit. This usually consists of a tube or bottle with a built-in one-way valve - this way, air will not flow back into the system when you release the pedal. If you use such a kit, follow the instructions that come with it. In both cases, you will need some fresh brake fluid of the recommended type and a special key for the bleeder valve.
1. Check the fluid level in the reservoir. If necessary, top up to bring the level to the "full" or "MAX" mark. Use only the recommended fluid type and do not mix different types of fluid. Never use fluid from a container that has been unsealed for a long time, as it will have absorbed moisture from the air, making it unusable. You will have to check the fluid level in the reservoir frequently during the bleeding process. If it drops too low, air will enter the system.
2. Set the parking brake. Jack up the front of the vehicle and securely place it on axle supports.
3. Remove the cap from the bleed valve on the slave cylinder (see illustration).
4. Attach the end of the plastic tube to the bleeder valve nipple. Fill the container about one-third full with clean liquid, then immerse the other end of the tube in the liquid.
5. Loosen the bleed valve slightly, then tighten it until it comes out easily.
6. Ask an assistant to depress the clutch pedal several times and hold it in the fully depressed position.
7. With the pedal depressed, open the bleed valve about half a turn. When the fluid stops flowing through the tube into the container, tighten the valve. Press the pedal again, and while holding it depressed, immediately release the valve. Do not release the pedal with the bleed valve open.
8. Repeat this procedure until no more air bubbles pass through the tube. Remember to constantly check the liquid level in the reservoir.
9. Tighten the bleeder valve completely, remove the tube and install the valve cap.
10. Check the fluid level in the reservoir again to make sure it reaches the upper mark, then test drive the vehicle to check the operation of the clutch.