Hydraulic Clutch System

Manual transmissions, or stick-shift/standard transmissions, are equipped with a clutch pedal that the driver presses to disengage the clutch. The clutch pedal, then, must be connected to the clutch by some system of components. This can be a clutch cable, or a hydraulic clutch system.

Hydraulic clutch systems are typically easier to press than a clutch cable system, but they are more complicated. In the hydraulic clutch system, the clutch pedal is attached to the clutch master cylinder, which pushes hydraulic fluid through the system with great force. That fluid cannot be compressed, so when the clutch master cylinder presses the fluid through the system, it travels through a hose and moves the clutch slave cylinder. This chain reaction continues as the clutch release fork, which is moved by the clutch slave cylinder, pushes the clutch release bearing (a.k.a. throwout bearing) into the clutch pressure plate, releasing the clutch.

This is a seemingly complicated system, but it is actually very much like any other hydraulic system, including the brakes.

Hydraulic Clutch System Signs and Symptoms of Failure

  • Clutch will not disengage when pressed
  • Grinding noise on every shift or inability to shift gears with the engine running
  • Clutch pedal is light or moves too easily
  • Fluid dripping from the hydraulic clutch system
  • Vehicle attempts to move forward with the clutch pressed
  • Clutch fluid reservoir is low or empty

Related Repair Advice for the Hydraulic Clutch System

  • If the clutch pedal cannot be pressed, the hydraulic system is likely in good working order, but mechanical clutch components may be damaged
  • Many vehicles will use brake fluid for the clutch, but check the owner’s manual and the cap of the clutch fluid reservoir for the proper fluid type when refilling
  • When air is found in the hydraulic clutch system, bleeding the air from the clutch slave cylinder is only a temporary fix, and finding the entry point for the air is required
  • Most hydraulic clutch components can be replaced without removing the transmission, unfortunately, replacement of the clutch or clutch release bearing requires transmission removal to access those components
  • Continuing to drive a vehicle with a defective hydraulic clutch system may result in internal transmission damage, especially synchronizer damage.

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