They rarely go bad. I had all kinds of trouble getting a rear master cylinder to get pressure. Was ready to buy another. I had 4 different very capable people try to help with no results. The mighty vac had it pressured up in 10 minutes. It can totally replace the fluid in the same time span. the vaccuum of the Mighty vac helps you move more fluid and air with each squeeze of the lever. I have since used it, on every bleed job with very little effort or time. Its a must.
