naku delikado yan! check your vacuum hose from alternator to hydrovac. pwede mong tanggalin yung hose from hydrovac and place your finger sa opening (car is idling). if it sucks your finger then ok yung vacuum. ikabit mo ulit yung hose sa hydrovac. kung nauubusan ka palagi ng brake fluid at no signs of leak sa lines, chances are may leak yung master cylinder mo at yung fluid pumapasok na sa hydrovac. pag di ka nauubusan ng fluid yung master cylinder mo may prob na marahil ribbed (may kanal) na yung loob ng cylinder na pumipigil sa pag-brake mo. palitan mo na agad.