How to Rebuild a Bottle Jack

Remove the oil reservoir plug from the jack and drain the oil into a pan. Unbolt the handle assembly and remove it, then pull out the pumping piston attached to the handle. This can be done by hand once the oil is removed, although you may have to put the jack in a vice.

Remove the release valve by unscrewing it fully. Check underneath for a ball or pin used to regulate the flow. Remove this using the pencil magnet.

Remove the overload valve. This is usually a screw close to the release valve. Remove the screw and inside you will find two balls and two springs, although there may be extra dividers and plates in there as well. Make a note of the order in which they come out so you can replace them in the same order later.

Use the pipe wrench to remove the tank nut on the top of the canister. Once this has been removed, the piston will come loose and you will be able to pull apart the piston into its component parts. Most of them are slid inside each other, so make a note of which goes inside which.

Replace the o-rings and washers with those from the rebuild kit or those you have separately. When prying off the o-rings, work on the side away from the sealing surface to prevent damage to the surface itself. It will help with the seal if you soak the o-rings and washers in hydraulic fluid before putting them in place.

Slide the parts of the piston back one inside the other and replace it inside the canister. Tighten the tank nut to hold everything in place.

Replace the balls and springs inside the overload valve. Usually the smallest ball will go in first, followed by the smaller spring and then the larger ball and larger spring. If you have extra plates or dividers then refer to the notes you took as you were removing them.

Replace the ball or pin in the release valve. This is usually just a case of dropping it back in to position. Replace the bolt on top.

Refill the jack with hydraulic oil and bleed air from the system. Bleed the air by opening the release valve and pumping the handle vigorously several times. Then close the valve, pump the jack to its full height, open the valve and let it back down. Repeat this until the jack extends all the way.

Wipe down the jack and then use it to raise and lower a vehicle. Check around the jack for any evidence of fluid on the outside that may indicate a leak. If there is a leak, then there may be an improperly installed seal.