Series 3 Clutch no pressure

Hi all, hoping someone can help
With the issue on my 1980 series 3. Last month I replaced my master and slave cylinders on the clutch. All was working fine, probably only driven 100 miles or so since changing them. Last weekend I drove to my brothers which is only about 1 mile away( again no problems ) when I got back in to come home there was no pressure on the clutch pedal. I looked under the hood and fluid was leaking out of the breather hole in the reservoir cap. Since then I’ve taken both master and slave off but still can’t get any pressure in the pedal. Anyone have any ideas what can be causing this? It goes in and out of gear with the engine off. Is it possible the parts I fitted are just faulty. Or is it likely to be a problem with the clutch or gear box? I’ve bleed the system up and Confident I’ve got all the air out. Any help would be gratefully received.
Many thanks

George

Sounds like the seal in the master cylinder has gone, a new seal kit might cure it or you may need a new master. Where did you get your replacement from?

Col

Thanks for your reply, I just got it on eBay.

There are some rubbish master and slave cylinders for sale on line, try to get a brand name one if yours can't be sorted.

Col

Did you set the free play up correctly at the master cylinder?
With pedal up on its return spring pushrod should have a gap betwee its end and piston of master cylinder 1.5mm from memory , seems strange that the system now has excess fluid in.