filling bottle jacks

[caterpillar guy]

How do you fill a bottle jack so it doesn't. Either not go all the way up, or after you release it it goes back up part way on it's own, from the oil being under pressure from pushing it back down.
 

[Jaden]

Fill to the oil level screw with the jack in it's normal upright position. If the ram springs up, you've got air trapped. Work it up and down a few times with the oil fill screw out.
 

[H2OK9]

With the jack sitting upright (never fill a bottle jack while laying on its side) on its base and the ram fully retracted, (all the way down) remove the fill plug. fill the jack with hydraulic jack oil. I found the easiest way to do this is fill a squirt oil can full of fluid and use this to fill the jack. after the jack is full to fill hole, open the valve and pump the jack slowly for 10 to 20 strokes on the plunger. (this will help bleed the air if jack was sitting on its side or empty). recheck the oil level, and making sure it isn't overfilled, replace the plug. If the seals and cups are in good shape, the jack should be ready for use.
 

[Ted in NE-OH]

Look at a post below for a discussion on Hydraulic Jacks and how to get the air out.
 

[Stephen Newell]

I just had to do that a few days ago for the first time. I took the fill plug off and it would only take a few drops. I figured out that if I lifted the arm as I was filling the fluid would go in. Then with the arm up I put the plug back in and let the arm go down and repeated the process. May not be the correct procedure but it worked.
 

[caterpillar guy]

I'll try the filling method. Thanks The one I had trouble with if I got enough fluid to run the ram out fully it would then push the ram out when down. If I took the fill plug out it would work fine until the plug was put back in. If I pushed the ram down then put the plug in it would create a vacuum and not let the oil into the plunger to push the ram out.