Ok
I have a 3-ton engine hoist that goes up about 1/2 way and then stops, it won't go any farther. It is an older used one. Could it be low on fluid? This is what I know. 3-ton ram, there is a rubber plug on the upper wall of the cylinder, has a hole for air to move in and out. The pump is the simple hydraulic jack type with a bar going up and down. The relief valve is also located there. I took the relief valve out and there is hydraulic fluid in there (I know cause it squirted me in the face) lol. Do I add more fluid in that relief hole, if so how much? or is there something else I am unaware of?

 

That hole where the rubber plug goes sounds like it's the fill hole for hydraulic fluid. If it is, I think you have to stand the cylinder upright and fill it up to the bottom of the hole. Put the plug back in, then bleed it by opening the relief valve and pumping the lever several times until the all of the air is gone. I'm pretty sure that's how it's done; at least on my hydraulic jacks. Good luck.

 

Make sure the piston is all the way in when you fill it.

 

yes make sure the ram is all the way in and the bleed screw is open a little add fluid replace the plug and pump the handle 10 times opening up the bleed screw until fluid comes out then tighten and enjoy