Just was given a couple of floor jacks. Bad news is one doesn't lift up and the other barely lifts the truck. I have put fluid in them. There is no id on them. Just wondering if anyone has had to (or can you?) over haul a hydraulic jack. Any pointers would be appreciated!

I just got a free jack as well.Did you know there is 2 places to look at the fluid? Mine has a big regular screw driver head in the base.And one plug on the pulp it self.The one on the pump is the one you want to put fluid in.Yours may just have air in it.My guess is you have a seal thats leaking.Jack up something and leave it for a hr or so and measure it when you start.The old jack i have will drop a few inches in 2 hrs.And it leaks ,does yours?Do you have a hydraulic dealer close to home?They may have a seal you need?

Didn't know that about the second plug! Thanks! No leaks as of yet.

Another trick to purge the air is to fill them with oil and then leave the valve open like you are lowering them and then pump the handle a few times, it will help work the air out of the system.

Also make sure your using the right oil too... I got desparate once and used ATF on a jack and got it to work but over time the ATF degraded badly. So I had a hell of a time trying to purge all the ATF out and reload with a good grade of Hydraulic oil. Once I did this I got full travel again! As for air bubble in the system you might have to leave the fill plug out and carefull raise and lower a few times to get the air out. Like mine I got air caught in it fill it and shoved the rubber plug back in... Well never the less it only travelled about half way and then when I released (lower) it shot the plug out with air pressure... My jack is really old and needs to be replaced or I need to pull the welder out and weld it back together...:eek:

safety first :smart:my brother was lifting the back so i could inspect the drums.he looked over to me and said, "its getting really tough". of coarse, i called him a puss and told him to lift my truck. the next thing i know the jack breaks and he ended up punching the asphalt. i never seen him so mad at me! but the jack said gm goodwrench 2.25 ton

That sucks... you right safety is a priority number one! Like in my case I always have a set of jack stands ready ot catch my ride...

i had a jack related problem yesterday when i went to jack up the engine with the shop crane. the dang thing wouldnt pump up for crap so i was forced to get a new 8 ton long ram at northern tool. i think the internal seals blew out? im going to take it apart and see if i could by chance source the seals at the local bearing/seal house. they can usually find one by od and id. i may get lucky and find that its just o rings? ive dealt with hydraulics but ive never messed with a chinese jack before.