am having problems with brakes on my sirion 1.3 el, have bled system , the brake pedal is firm and at the right height when done but as soon as i start the engine the pedal goes to the floor when applied, have tried another master cylinder but that made no difference thought master cylinder may be u/s but was informed that it was ok and that it may be the brake compensator ?i assume that air is getting into system has anybody else had this problem