by 1972nail » Sun May 05, 2019 5:44 pm
Do the pistons move back in easily and release the brake if you release the pressure at the bleed nipple? If it doesn't then the wheel cylinder is sticking. If it does then pressure is being retained in the system. First check that the rear flexible hose is not swollen or damaged internally. That can cause the hose to act like a one way valve. Replacement is the only option. Damage can be caused by clamping the hose to prevent fluid loss while changing the cylinders.
If you are convinced that the hose and cylinders are not the problem then try slackening the rear brake pipe connection at the master cylinder to release any pressure that may be in the rear line. If the brakes release then it's the master cylinder that is holding the pressure on. Be prepared for fluid loss, wrapping a cloth around the connection would be a good idea.
However, It could also be a sticking pedal, but unlikely. But I would still check that there is no carpet or sound deadening around the pedal box and the mechanism.
Editor of the VVOC Magazine ReVival
"When you have a Firenza like mine, who needs any Minis?" copyright David Maxwell 1979.