Chrysler Repair: voyager brakes, vacuum fittings, master cylinder

Question
on my 97 voyager i have to keep bleeding my brakes every fortnight. despite 2 visits to a garage the mechanic cant find a problem.its not losing any fluid but after a couple of weeks the pedal is on the floor with no brakes at all,  any ideas??

Answer
Hi Dave,
If you aren't loosing fluid (other than bleeding) I would wonder whether you might have a master cylinder that was either not bench bled properly or has a worn seal producing an internal leak. If not that, then similarly with the power brake unit (check the vacuum fittings) as this can cause a "run out" of the unit wherein the pedal goes to near the floor.
Roland