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Old 07-15-2010, 07:39 PM   #1
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Default How do you bleed a hydraulic jack?

Put new o-rings in an old Sears floor jack, Now no leaks. What's the process for bleeding the air out and refilling the lost oil?

Looking to buy Par-X tools, please IM me if you have any FS.
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Old 07-15-2010, 09:33 PM   #2
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Default Re: How do you bleed a hydraulic jack?

Stole this from google
Both of the above methods of bleeding your jack are incorrect.

But before I explain a simple bleeding procedure keep in mind that there is a reason for your jack needing fluid in the first place. There is a leak somewhere. Usually the location of the leak is easy to locate. Thoroughly clean the jack. Set it on a piece of cardboard. Pump it a bunch of times (say 20 or more). Now let it sit there without moving it. Depending on the severity of the leak, the cardboard will show fluid within hours or a day or two. Now it's time to be a detective. Carefully examine the jack directly above where the cardboard show fuid. But don't be fooled. Sometimes the leak starts in a certain spot on the hydraulic unit, and then, because of the shape of the said unit and gravity, it runs to another spot where it finally falls on the cardboard. If you cleaned the jack real good, you'll be able to follow the fluid trail by examining it real closely with a flashlight.

Depending on how fast the leak is, you might be waisting your time filling the jack, and bleading the hydraulic unit of air. A profound leak will prevent the jack from operating.

Also, there are other reasons why your jack may not function correctly. Most jacks have an overload valve and a bypass valve. If there is dirt, or sludge, or any foreign particle in the hydualic unit, it could affect the operation of these valves. Are you sure you needed fuid in the first place. The inside of a hydraulic unit need to be surgically clean to have long life and function properly.

Always use hydraulic fluid. Other types of fluid will most likely ruin the seals inside the unit.

Now, as to the bleeding procedure for most jacks:

1. Fill the jack with hydraulic fluid to the proper level. It is possible to overfill the resevoir on some jacks depending on their design. Refer to the paperwork that came with the jack.

2. Leave the Filler Plug OFF. With the Release Valve OPEN (as if you were letting the jack come down), pump the handle about 20 times.

3. Put the Filler Plug ON. CLOSE the Release Valve. Try to jack up the unit. If it works, you are on the right path. Note....I would do steps 1, 2, and 3 a few times.

NOTE: Never raise the Lifting Arm of the jack manually. This will suck air into the hydualic unit. Also, when traveling with the jack in a vehicle, alway have the Release Valve OPEN, and the jack in an upright posistion (take the Handle off if necessary. This can suck air into the hydualic unit when you go over bumps in the road.

If this did not fix your problem, there is most likely an internal problem within the hydraulic unit. If the jack is not an expensive one, don't bother having it repaired. It would be cheaper to go buy another one.

CAUTION...Any jack, leaking or not, can have a catastrophic failure while under a load. ALWAYS USE JACK STANDS. ALWAYS USE JACK STANDS. ALWAYS USE JACK STANDS.
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