What are the Clutch Master Cylinder & Slave Cylinder all about?
A clutch master cylinder contains a reservoir that stores the brake fluid. It is connected to the clutch slave cylinder through hoses. When you push the clutch pedal, brake fluid flows from the clutch master cylinder to the slave cylinder, applying the pressure necessary to move (engage) the clutch.
It has internal and external seals that can fail. If the external seals wear out, the clutch master cylinder will leak brake fluid, reducing the amount of fluid in the car and causing the clutch to malfunction. You may also find leaked brake fluid down by the clutch pedal (inside the car). If the internal seals wear out, the clutch fluid will continue to circulate inside instead of being directed to the slave cylinder. In that case, the clutch pedal will go all the way to the floor when you apply the clutch.
Keep in mind:
- Whenever the clutch master cylinder is replaced, it is recommended to replace the slave cylinder as well. When the master cylinder goes bad, it is extremely common for the slave cylinder to follow suit.
- Note that some clutch slave cylinders are installed inside the transmission. To replace this type of slave cylinder the transmission has to be removed.
How it's done:
- Inspect clutch master cylinder and slave cylinder.
- Check the condition of brake fluid.
- Inspect the operation of clutch pedal.
- Remove and replace clutch master cylinder and slave cylinder.
- Bleed all air from the master cylinder.
- Test drive the vehicle.
- During an oil change, the mechanic should check the amount of brake fluid. If you feel a change in the way the clutch pedal feels (softer pedal) when stepping on it, you should have a mechanic inspect the clutch master cylinder and hose.
- Clutch fluid should be changed every 24,000 miles.
What common symptoms indicate you may need to replace the Clutch Master Cylinder & Slave Cylinder?
- Clutch pedal goes all the way to the floor.
- Brake fluid leaking around the clutch pedal.
- Not able to change gears.
How important is this service?
The clutch master cylinder stores brake fluid. When the clutch pedal is depressed, the fluid is transferred from the clutch master cylinder to the slave cylinder, which provides the pressure needed to engage the clutch. If the clutch master cylinder is leaking, it won’t hold the proper amount of brake fluid, and there won’t be enough pressure from the fluid to engage the clutch.