Hydraulic Jacks

[Ted in Ne-OH]

I have a couple of 12Ton hydraulic jacks that crap out when trying to lift my little tractor. How hard is it to rebuild them and is there a tutorial on the web some place. Fluid is good.
 

[rufus80]

What kind are they, US or China/Japan? If US go to a hydraulic service shop and buy a kit. If China/Japan go buy another jack, not worth time or money fixing.
 

[fredfromwyo]

If the jack doesn"t leak oil, I always just pump them up as high as they will go, valve closed, and turn them upside down and go off and leave them. Hours later I open the valve, while still upside down, and colapse whatever amount it had jacked. Set jack upright a few minutes and repeat the procedure, and it seems that every time they will jack some higher, and seems after four or five cycles of this they seem to work. One good tip: always close the valve and park right side up. works for me.
 

[PJH]

I'm gonna try that Fred - thanks
 

[LenND]

Do like Fred said but instead of leaving jack set for a while just open valve and push jack down by hand or foot. What your doing is getting rid of air in the line. But your problem may be inside. There is either a single cup leather or a set of O rings on the end of the piston that are wore . So when the jack gets to the load the fluid seeps past them.