Floor jack help

[Braindamage1]

Need your help. Have read all the posts and still can't figure it out.

Have an old Craftsman 1 1/2 ton jack, 727.12102. Same as a Blackhawk SJ-2 best I can figure.

Won't jack up well, sometimes not at all. Higher it gets, less lift I get per stroke. Plunger feels mushy until it bottoms out. No leaks, full of oil, no air in the system.

Do I need to rebuild this? Don't see others with same issue.

Sentimental value so don't want to junk this old timer.

Thanks

 

[Roberts210]

No, no, no, do not junk your Craftsman jack. It's probably a Shinn-Fu. Is it green?

 

[Hiball]

Yes, the Oem is Blackhawk and a SJ2 in disguise, well before shinn fu acquired the Blackhawk label. When you say it's "full of oil" that may very well be your problem, too much oil can cause poor performance, a weak pump seal will amplify that effect. If it's in good shape, I would hesitate to freshen it up.

 

[Braindamage1]

Well, let some oil run out so now it's not quite so full. Also removed the cap and spring over the pump so I could cycle it by hand and see if it was doing anything (thought about taking it off but didn't want to budge).

NOW IT PUMPS UP but I sure can't figure out why.

 

[Braindamage1]

Figured I'd try to post a pic, let's see if this works.

 

[Hiball]

Well, let some oil run out so now it's not quite so full. Also removed the cap and spring over the pump so I could cycle it by hand and see if it was doing anything (thought about taking it off but didn't want to budge).

NOW IT PUMPS UP but I sure can't figure out why.

Too much oil + sealed reservoir = pump seals couldn't overcome the vacuum created by the lack of head space, which is why the lifting performance worsened with every pump.

 

[Braindamage1]

Got it!! Appreciate the help.

 

[Roberts210]

It's green! Looks like a winner.

 

[Roberts210]

I rebuilt this jack for my buddy who needed a good jack but who is not very tool conscious. He left the jack in a shed on his farm for four months and now he can't rotate the handle. Where he left the jack it was probably out of the weather, except for very high wind and rain, but cows use that shed and it is VERY possible the jack got pissed on. It's possible it was pissed on multiple times. He went to jack up his truck, and the saddle would go up but he couldn't lift the truck. I am out of State, so can only advise him via email. I told him to try to rotate the handle CCW.

Here is his email from this morning: I also tried to free up the green hydraulic jack. I put a lot of liquid wrench at the meeting point between the (white) handle and the (green) body of the jack. And I used a pipe wrench to try to move it - no such luck! I could wiggle both gears maybe 1/8" with my finger, but couldn't move that handle even a thousandth! Couldn't believe I couldn't budge it - even waited 45 minutes and tried again - without any success. It is really locked up!