help with rear brake cylinder

[martin53]

Im having trouble with one of the rear brake cylinder. There fine when i bleed them but later when driving the rubber in the bottom cylinder shoots out with brake fluid. Should i replace the rubber piece or is it something else causing this. Oh its on a 53 dodge pickup.

[Dave72dt]

I'm surpised no one has answered this for you before now.  The frist rubber you'll see is a dust cover.  Fluid is not supposed to be comingout of this.  Behind it is the piston that moves the shoe out when  you push the pedal.  Directly behind the piston is a rubber cup that is probably worn or damaged.   The flard side of the cup goes toward the fluid.  Hyd pressure pushes against the flard sides to helpseal it against the cyl.  the cyl may also be scored or rust pitted which will also impair the sealing and allow fluid to go past and escape.  A repair kit may work, often the cylinders are replaced.