[Shop-talk] Hydraulic Jack Diagnosis

[Donald H Locker]

That's an odd set of symptoms. An inability to raise a load sounds like
air in the hydraulic system. Leaking seals or valves would cause a load
to drop with oil passing through the seal/valve.

With no load, the air pressure doesn't collapse the bubble so the jack
rises; but with a load, any pressure collapses the bubble instead of
raising the load. The fact that it holds after it was raised supports
this hypothesis.

I think just opening the oil filler screw (and maybe topping the oil)
will fix it.

HTH,
Donald.

On 2022-05-22 14:03, Jeff Scarbrough wrote:
> Just trying to keep from going down the wrong rabbit hole..   On
> Thursday, I think I blew up the TR6 differential.  I pulled out my handy
> Craftsman 3.5 ton floor jack (50145) and discovered it will not raise
> any weight.  It will pump up with no load, and does not seem to creep
> down under the load of my immense personal bulk.  To me, this indicates
> a pump problem - seals or valves.  It is full of oil, and has worked
> well for the last 25 years or so.
>
> I found a kit that seems reputable for $30 (
> https://www.hcrcnow.com/shop/seal-kits/product/8118
> <https://www.hcrcnow.com/shop/seal-kits/product/8118> ) that contains
> all the seals to rebuild it, but that place doesn't carry oil.  I can
> get any number of different brands of jack oil locally, so I don't think
> that's going to be a problem.
>
> Any other thing I might check before I pull the trigger?