Re: How to fix a Harbor freight 12 ton hydraulic jack

Fred Cisin

Can we assume that it is a conventional bottle jack used in it?

The most obvious possibilities is that it may be low on fluid, or it may have air in it. (which will let it pump up, but not under load, as the air is compressible)

With the ram fully retracted, the fluid ("hydraulic jack oil", but some try to get aaway with ATF), should come up almost to the hole.

MOST can be adequately bled by pumping with the filler plug open, . . .

On Tue, 23 Feb 2021, sujit roy via wrote:

Hi Have 12 ton HF press. The jack that came with it, has stopped working and I can't figure out how to fix it. There an many YouTube videos but not on this type. This type has a plug on the side. Underneath the plug is a screw. I removed the screw and put back which I think was a no-no.  Does anyone know how to get this type working again? The jack without load seems to go up, but when load is applied it, bounces up and down at the same spot. Sujit

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