Firstly you will need to check fliud lines ans slave cyilinder for leak's. The fluid must have gone somewhere?
C10 BLEED THE CLUTCH SLAVE CYLINDER
Remove the clutch reservoir cap and diaphragm. Check the fluid level. Fill the reservoir to or above the step mark. Install the cap and diaphragm.
Depress and release the clutch pedal several times to stabilize the clutch hydraulic system.
With the vehicle in NEUTRAL, position on a hoist.
Remove the bleeder screw cover and attach a vinyl hose to the bleeder hose. Place the other end of the vinyl hose into a clear container partially filled with brake fluid.
Have an assistant depress and release the clutch pedal five times, then hold the clutch pedal down. With the clutch pedal depressed, loosen the bleeder screw to let air escape the clutch system. Tighten the bleeder screw. Repeat this process until no air comes through the vinyl hose.
Tighten the bleeder screw and install the bleeder screw cover.
Slowly pump the clutch pedal several times to verify there is no fluid leakage.
Fig. 12: Bleeding Clutch Slave Cylinder
Courtesy of FORD MOTOR CO.
Depress and release the clutch pedal two short cycles, and three full-travel cycles.
Make sure the clutch reservoir is at the correct level. Refill as necessary.
Does the clutch hydraulic system operate correctly?
Yes : The clutch system is OK. TEST the system for normal operation.
No : VERIFY customer concern. CONDUCT a diagnosis of suspect components.