How to Bleed Air From a Jack

You can bleed air from a hydraulic jack.

A hydraulic jack uses oil under pressure to lift heavy objects. These jacks are commonly used both at home and auto service centers, as well as for many industrial lifting applications. They come in a variety of shapes and sizes, with some looking like bottles, hence the name "bottle jack," and others with long lifting arms called floor jacks. When hydraulic jacks are full of oil but no longer lift properly, the most common culprit is air in the mechanism. Bleeding air from the jack will restore it to proper functioning.

Things You'll Need

• Wrench if applicable

Instructions

1. Release the pressure in the jack by opening the release valve. Allow the jack ram to fully settle into its base.

2. Remove the hydraulic oil filler screw. Some jacks will have a finger screw that can be turned, while others may need a wrench or a screwdriver that will loosen it. These screws will be located on the body of the jack, and are used for refilling the hydraulic oil cylinder. If the screw is on the side, the jack must be placed on its side so that once the screw is removed the oil filler hole is on the top. This will allow air to escape without spilling oil.

3. Pump the handle vigorously up to 10 times with the oil filler screw removed. This action will purge and bleed the air from the hydraulic system. Trapped air may bubble out as it leaves the system, so keep your distance when pumping the handle.

4. Replace the oil filler screw tightly.

Tips & Warnings

• Once the oil filler screw has been removed, the oil level can be checked, and if needed, oil can be added. Refer to the specific filling instructions for your type of jack.

• Wear gloves when handling hydraulic oil. Pressurized oil may spurt from the oil filler hole, so keep your eyes safe and wear safety glasses as well.

References

• Voyager Web: Hydraulic Jack Troubleshooting Guide, Page 3
• Craftsman Floor Jack: Know your Jack Figure 3--PDF File