Most of the time I'd say it's either the master cyl or the slave cyl starting to go bad, allowing air into the system. A stock, new master cyl or slave isn't that expensive and it's always fixed it. I have tried rebuilding both, and half the time it doesn't work, so I end up buying a new hydraulic cyl anyway.
Sometimes you get lucky and it's just low fluid, requiring a refill and a good bleed. I used to use my Mityvac, but I have found it's easier to backflush w/a 60 ml syringe & a short length of clear plastic tubing hose-clamped to the slave bleeder nipple. The back flush method was suggested by another member, and after trying it, I have found it works better/more-quickly to bleed the clutch slave/master setup than my Mityvac use did, not sure why, maybe something to do w/the design of the system & air becoming trapped where the upward-movement of fluid helps the air bubbles/pockets to dislodge and migrate upstream to the master cyl.
Sometimes you get lucky and it's just low fluid, requiring a refill and a good bleed. I used to use my Mityvac, but I have found it's easier to backflush w/a 60 ml syringe & a short length of clear plastic tubing hose-clamped to the slave bleeder nipple. The back flush method was suggested by another member, and after trying it, I have found it works better/more-quickly to bleed the clutch slave/master setup than my Mityvac use did, not sure why, maybe something to do w/the design of the system & air becoming trapped where the upward-movement of fluid helps the air bubbles/pockets to dislodge and migrate upstream to the master cyl.
Last edited: