Clutch stuck - Rock Solid (intermittent)

Hi there, hoping for some advise. I have a 1991 Defender 110. This is an intermittent problem, most of the time the clutch is working fine but every now and then it is rock solid. Sometimes this last for quite a while causing real issue, sometimes it only lasts a couple of presses and then is back to normal. I have replaced the slave cylinder but it made no difference so I replaced the master cylinder and it is still doing it. Any ideas would be gratefully received. many thanks Chris

Have you checked the flex hose is not collapsing internally?

Hi Lynall, I haven't checked that. It looks in good condition from the outside but is the a way I could confirm it is ok on the inside? Cheers for your reply

when solid, is it worth taking the slave off and seeing if the fork is jammed manually? maybe it's about to fail?

It looked perfect and is a heavy duty fork, but it is worth a try, might eliminate some parts from the equation. Thanks

Hi, I've replaced the flexi hose but it still hasn't fixed the problem, any ideas would be gratefully received.

If the pedal is solid and you have replaced the cylinders, IMO it suggests something amiss at the fork/pressure plate/bearing.

Have you checked nothing is jamming the top of the pedal under the cover with 6 screws?