Morris Minor Owners Club

could i block the breather hole to stop leacking, if so what would hapen long term wise with the break fluid.

Hi I have replaced the brakes and bled them. however every time i push the breake peddle down the break fluid keeps jumping up, and jumpung through the breather holes in the lid of the master cylinder. it is a 1971 morris miner pickup and i would like to know what you think the problem could be and ...