Bottle jacks help mechanics lift heavy vehicles. The tool is part of almost any mechanics arsenal. Bottle jacks use hydraulic leverage to lift vehicles, and completes the task more quickly than any other jack. Without a jack, mechanics can be without means to fix a vehicle. Bottle jacks' purchase or repair is expensive, so try fixing it yourself before buying a new one or paying for repair.
Check to see what the weight limit is on your jack. It should be written on your jack or in the documents that came with it. Check the weight of the car. It is often written on the driver's door panel. Don't lift a vehicle with a jack that can't handle the weight. You might injure yourself or your property.
Extend the jack fully by pumping it with no weight. If the jack is so damaged that it can't do that, then have someone pull on it as you pump. You can also open the release valve, which is located on the opposite side of the pump and pull the piston out. Now you can extend the jack without any pumping. While the valve is open, check to see if there is any oil build-up. You should see a bit, but not much. If there is dirt or other substances, you have a bad seal. Look near the bottom of the piston to see if there is any damage. If there are cracks, you need to take the jack to a repair shop.
Open the jack's oil reservoir filler cap inside the valve. Make sure the hydraulic oil is at least a quarter-inch below the hole. Fill it to the quarter-inch mark, but not higher. The cap is the uppermost cap in the jack. You might need to open it with a screwdriver.
Wipe down the jack with a cloth. Open the release valve; quickly pump the jack's handle several times. Check to see if any oil is leaking. Close the valve; pump the jack to its full height. Open the release valve again to bleed the jack if it still won't rise. If you see a leak, trace it to the seal that is generating it. Take it to a professional to replace the seal.
Try lifting a vehicle with your jack. Your pump might not be latching if it still won't lift. You will need a new jack or a repairperson might be able to fix it.
Work in a dry and clean area.
Only go under a vehicle that is lifted by a jack if you have jack stands. Hydraulic fluid can burn. Don't try to fix your jack around open flame.