New master cylinder wont work??

Rusty is correct. But, if you haven't refreshed the brake fluid in 3 years, you should flush thru new fluid anyway since glycol absorbs moisture and rusts the innards once it absorbs too much. Oops, make that every 2 years since you live in IN. You can go a little longer if you use DOT 4, or forever if you use DOT 5 (silicone) like me.