hydraulic cluch question

I've got a hydraulic clutch setup on my CJ6 using an 80s era CJ master and a speedway motors pull type slave. It works well, but under lots of clutching, seems to pump itself up, as if all the fluid isn't being pushed back to the master. Never seemed to have this happen with other clutch slave setups. If I undo the hydraulic line, the slave goes right back in. Almost seems to be a pressure holding check valve in the master. Could this be the case? The thing I worry about is it riding the throwout bearing on the pressure plate fingers. Anyone have any thoughts?

 

Maybe your return assist spring has lost it's tension or you need a stronger one.

 

I assume the master is on the firewall higher than the slave? And the level in the reservoir is at the right height?...........some systems are sealed some are vented and provide for either venting or space in the reservoir for the fluid to return.........You could also have a small leak at one end that on the return stroke is sucking air. Try bleeding it again and and reseal all the fittings.

 

Tarry, you have me thinking now....the cap may allow air into the reservoir, but not allow it to escape creating a small pressure in the system. The system is "mix n match" components. It doesn't ever hold enough pressure to release the clutch, just enough to have no play at all which makes me worry about the throwout bearing. Hmmmm..vent the cap, and heavier return spring may do the trick..thanks guys.

Frank