Help with floor jack, leaked and won't pump?

You need jack fluid which a "real" parts store will have.

Jacks are simple, just be careful and watch CAREFULLY for check balls and springs.

The no1 thing that will "gotcha" is this:

Most jacks operate "sealed." That means the reservoir where the fluid rests has an air bubble, and as you extend the jack, that air pressure is reduced, as the fluid is removed, and pushed into the cylinder, extended. The "worst case" scenario would be if you filled it clear up so there was NO air. It would immediately pull a vacuum and "hydraulic lock" on the suction / reservoir side, and the pump would lose prime.

The other end of the story is not enough fluid, simple.......it pumps the jack up until it sucks air.

So you have to balance the amount of fluid in there "just enough" and "not too much."

I have one old import floor jack that I could "never get right". (I think it was designed wrong and never WAS right) So finally I simply "ran" it with the FILLER CAP LOOSE which acts like a vent. Yes, it leaks, and yes, I have to add fluid once in awhile.