A clutch master cylinder is a component found on most modern manual transmission systems. This component converts non-hydraulic pressure into hydraulic pressure. A failing clutch master cylinder can have significant effects on a transmission's performance, from maintaining speed to engaging the clutch.
The clutch master cylinder may develop leaks in its seals that create a pressure drop when the clutch is depressed. This may prevent the clutch from releasing. Leaks in the clutch master cylinder may also cause the clutch to engage early; for example, when the vehicle is attempting to accelerate from a stop, it may lurch suddenly as the transmission slips a gear and stalls out.
Soft Clutch Pedal
A clutch pedal that is experiencing pressure problems due to a failing master cylinder may feel soft when it's depressed. A driver may notice the pedal showing less than normal resistance when attempting to shift gears. This problem can also be caused by leaks in the master cylinder's clutch slave cylinder attached to the clutch pedal along with the master cylinder.
A clutch that slips has difficulty maintaining gears. In a newly installed clutch this condition can be caused by a blocked master cylinder port. Blockages can occur from road particles fouling vehicle components or a fluid leak from another part of the vehicle finding its way into clutch components. Drivers may experience this as a spontaneous loss of speed when the vehicle is on the road or difficulty in accelerating from an idle position.