Master cylinder, Joe, Master Cylinder. It needs to be replaced. Dan Nees cookiedan@domain.elided 1979 Scout II 345, 727, D44's w/3.07's, 4" Triangle lift. 1971 Scout II 304, D30/44, D20, power steering. http://members.tripod.com/~IHCaholic/scoutindex.html Now with Pictures!