hi,here's my problem,i've put four mastercylinders on my van in six months,they work fine for 3 to 4 weeks ,then the pedel starts going to the floor,the brakes were bled by the dealer who also replaced the mastercylinder,installed new flexible hoses,a proportioning valve,one bad wheel cylinder,checked the antilockbrake system and charged me $700.00 for the service.the problem still exist,but the dealersays they don't know what else to do. i have a great minivan but can't drive it with no brakes.i would appreciate any advice on what might be causeing this problem, how would you go about bleeding the abs system?[img]smileys/smiley6.gif[/img]