4 Ton Floor Jack Wont Pick up Load

[Farmer2]

Hi Folks, I have a 4 ton large floor jack that is full of fluid and was working fine until the other day. I can jack it up all the way and then hear the bypass fluid go by when I reach its limit on height.

If I put under my car it will attempt to raise it but it seems like it is bypassing again and wont raise any further. I have tried to bleed and also filled fluid. I have not unscrewed any other screws besides the plug with the vent hole in it to top off fluid.

This pump was rebuilt professionally 8 years ago and no issues until now.

I should say that it all started when I noticed after raising my car it would creep down and not hold then it got to the point of not even jacking back to that point.

Any help would be appreciated!
Thanks, Dave

 

[6PTsocket]

Sounds like the seals are shot. They are not hard to rebuild and kits are available on line for anything but the cheap imports. Since it was rebuilt once I assume there must be a kit. The one thing you don't want to touch is the adjustment screw for the bypass. If the price isn't too bad,have it professionally rebuilt again. I assume it is not leaking and you checked the fluid level. Good luck.

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[Art From De Leon]

Perhaps the release valve isn't fully seating. Open it fully open and pump the jack a few times in case a grain of sand somehow is lodged on the seat.

 

[gdocktor3]

Message the member Hiball. He'll tell you everything you need to know, plus some.

 

[Hiball]

I would need a little bit more info to fully give you a starting point that might prevent a total tear down, let's at least start with the Make and Model, so I can know what kind of hydraulic delivery system I'm dealing with.

 

[Farmer2]

Sorry for the long away, work has been crazy!
It is a Walker J series 93657.

Refresher, full fluid, pumps all the way up with no load, with load-as soon as it touches my frame on the truck it just pumps with no raising. Very easy effort to pump. It was rebuilt by a hydraulic pump guy about 15 years ago.

Does it need to be rebuilt again or can I get away with certain parts to get it back in shape?

Thanks, Dave

 

[Farmer2]

Pics of cylinder rams.

 

[Hiball]

Sorry for the long away, work has been crazy!
It is a Walker J series 93657.

Refresher, full fluid, pumps all the way up with no load, with load-as soon as it touches my frame on the truck it just pumps with no raising. Very easy effort to pump. It was rebuilt by a hydraulic pump guy about 15 years ago.

Does it need to be rebuilt again or can I get away with certain parts to get it back in shape?

Thanks, Dave

If it was mine, I would elevate the rear of the Jack and pull the Power side valve and make sure you don't have a piece of debris preventing the lower ball from seating.

 

[Farmer2]

Ok, status is in. I ordered the rebuild kit from hydraulic parts supply and tore into the hydraulics. It was in need of soft goods for sure.
The reason I could not pump up was that the three cups on the power piston were on wrong, well 2 of the three. the first was the correct way and the back two weer on backwards. Went through it all and sealed it up. Put it together this past Saturday and it works excellent!

Thanks Hiball for the parts recommend and advice from all for this project.
It was pretty straight forward once I got the huge nut off the tank ;-)

Dave

 

[Farmer2]

Oh yeah and I recommend everyone to stamp the model make and such into the solid steel frame so as not to ever lose the important info that gets lost in a label!