Sears 3 ton floor jack - changed fluid won't work??
 

I changed the hydraulic jack oil in my sears 3 ton floor jack. I dumped the old oil into an oil container. Noticed a spring fell out of the drain hole, I reinstalled the spring through the drain hole, then filled with hydraulic jack oil and replaced the drain plug. I then turned the handle to the right (lock position) and pumped and pumped, no joy. I then removed the drain plug and turned the handle 1/2 turn to open and bleed the system. I pumped and pumped and with each stroke, some oil came out. I then refilled with oil and reinstalled the drain plug. I locked the handle in the lift position and pumped and pumped, no joy. what am I doing wrong?

The plug you removed was not a drain hole, it is a check ball location. There should be at least one 1/4" ish ball in there and sometimes two. The ball goes in first then the spring. If there are two, install the small one first , large one then spring.

you are so right, I located the two balls, one small one and one larger one. the spring is tapered. so, is the order of installation:

1. install small ball
2. install large ball
3. install spring with larger side facing down?

here is a link that shows how to properly install the check balls in a floor jack if you happen to have removed the wrong plug (like I did).

HYJACKS.COM/JACKS BASICS PAGE/H7.HTM

Thanks for the link.

jack service
 

Thanks for a very informative link .

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for a sears craftsman three ton floor jack, this information is correct. the link I listed HYJACKS.COM/JACKS BASICS PAGE/H7.HTM shows incorrect ball and spring installation diagrams for the sears hydraulic floor jacks.

Did you try the online Sears parts site? There might be a breakdown there.

As for the spring, take a look at the plug that was removed, usually there is a rubber gasket disc on the end, take a look for a spring imprint.

It's one of those " I 'd have to see it " deals. If the small side is too small, the spring might flip to one side of the ball and keep it from seating. If the large side is against the ball, it might hit the bore before it contacts the ball.

The small ball lets fluid from the reservoir into the pump on the up stroke, the large ball lets fluid leave the pump and keeps it in the lift piston. Think of the way a mechanical fuel pump works.

Thanks, I"ll check the Sears site for more information. At first, I put the little ball in, then spring, then big ball......no joy. So then I followed the first set of instructions posted and installed the small ball, followed by the larger ball, then the spring with the large side of the spring facing up. VOILA! the jack works! I have it holding up the right front of the 560SEL overnight just to make sure it won't leak down when I do the brake pads tomorrow. so far, so good........


Note to self: never remove the check valve mechanism, only change the hydraulic jack oil through the oil filler cap/hole.

USE A JACK STAND! never rely on just the jack

for sure, I'd like to have a garage lift so that I don't have to deal with floor jacks.