Floor Jack Repair??

Hey all,

I was given 2 floor jacks by a relative a few weeks ago. I started investigating into one tonight as to why it doesn't want to lift and what I found is this:

JACK #1

Jack shows no visible signs of leaking (IE dust/dirt buildup)

Seems to be nearly full on oil.

Seems to jack no harder/easier than my working floor jack.

I tried it tonight, and with the "fill plug" removed, if you stroke the handle, you can see the fluid go down slightly (like it is pumping the oil) but as soon as you lift the handle back up to take another stroke you can see the oil level in the reservoir rise, like the fluid is not entering the cylinder itself.. as it makes NO ATTEMPT to raise. Lift/lower valve seems to be closed all the way.


JACK #2

I have not looked too deep into this one yet, but this one as you stroke the handle, the jack will raise, and as soon as you bring the handle back up, the jack falls back to original location.. IMMEDIATELY.. not slowly.. it drops as slow/fast as you pump the handle. Again, shows little/no signs of leaking oil.

Both of these jacks appear to be of pretty good quality, so if I could fix em reasonably I'd sure like to..

Anyone got any pointers on where to begin with either unit? I have a feeling they both have about the same issue.

TIA,

Brad

I would expect a bad seal/o-ring on the plunger- let"s the oil bypass instead of going to the lift cyl. You"re pumping the handle but not moving the oil.

Sounds like a bad check valve on no.2, maybe
someone took it apart and a little ball fell out?

These jacks have been abused!!!! What I mean is they have been used to lift way more than they were rated for. Ex. 3ton rated jacks made to try and lift 8 to 10 ton. Rolled or damaging inner
"O" rings. gg

Jack 1 has a leaking intake check valve, #2 has a leaking exhaust check valve. Probably dirt and or/ rust. Draining, flushing with diesel, and new oil may fix them. I may have diagrams to show the location of the valve plugs.

I'm with JMS...The plastic seals inside the cylinder are prolly crumbling and leaking . I fixed several with seals from a big hydraulic parts co in Los Angeles, A.C.DePuydt

i'd also be looking at check valves and orings.

soundguy

Thanks so far guys..

UPDATE: I played with jack #1 today.. I got it to go up, but will not stay up very long. It acts like whatever "closes" to hold the pressure for it to rise is not functioning properly.

I called it a early night tonight, as I'm not feeling all that energetic today (little sleep last night and got up way too early) So, tomorrow I will take my camera along and snap a picture or 2, and maybe you fine men can guide me a little bit on what to do from there.

Thanks again
Brad

http://www.hyjacks.com/H7.HTM

You can spend countless hours messing with a jack and get no-were BTDT,, take it completely apart and be done with it... You will learn how it works , how simple it is, will find rust and moisture in the reservoir that can only be removed by disassembley,,,Worst case you will loose 1 hour of your time.

Thanks for the positive comment, but I think others are more right- they took care of both the up and the down, especially the check valve comment. Either way, the problem is in the pumper thing, not the main lift cyl. Some years ago I built a hyd press...about 500 lbs steel. posted some pix here- it is in archives. Someone bellyached that it was not painted.....did I care?...Anyway, bought a 20 ton jack for it, my land renter needed a 2 inch bearing pushed off of a shaft- I got it off, with a 3 foot cheater bar...very first push on that 20 ton jack. Ruined it. Bought a 30 ton. Will never break that one....upper press frame is 1 1/2 inch plated beam.

Thanks for the link Hobo.
What I have found a couple of times is bits of plastic holding a check ball open.

Here is a link that I came across on jack repair.
Floor jack repair

Thanks for the links guys..

The more I look, the more I think this is a project i can easily tackle. The more I READ, the more I think someone else thought the same thing and dropped a part or 3 somewhere.

I guess best bet is to wipe the barn dust off the stickers and see what brand they are, and hopefully find a parts breakdown to see what is missing (or not missing)

I'll post a update later..

Brad

The one that I had which did that had a bad seat on one of the internal ball check valves. Took it aprt and refaced the seat, cleaned and reassembled and it works great now. It was full of metal machining debris which caused the seat to be damaged.

Some more info that may help

http://www.marcorubber.com/oring_guide_old.htm

http://www.columbiaerd.com/static_axial_external_sealdesign.html

http://www.allsealsinc.com/nationalorings.html

I highly recommend folks play with o-rings and get a handle on measuring them go to the size chart and cross them over... are pay $5 for a 10 cent o-ring from yer local tractor dealer... Most common o-rings can be found in a universal o-ring kits



http://www.google.com/products/cata...i=psqhTdXuJ8aztweB_dj0Ag&ved=0CDgQ8wIwAg#

I have found dirty/sticky check valves on them. The older jacks had drilled passage ways with spring and balls. The newer designs have a removable cartridge assembly with both checks in them.

I repaired hydraulic jacks for many years. The
valves are spring loaded ball bearings. the
valve seats get pounded out and have to be
re-machined, or they get corroded or full of
sludge or varnish, and won"t hold. If the
rubber/plastic/leather seals are OK, or replaced,
then the problem is the valves. Professional
jack repair shops have reamers to clean/polish/
re do the valves. I had brazed old valve balls,
(ball bearings) to brass rods and used fine
lapping coumpound to clean up valve seats with
much success. Still 2 or 3 of 10 old jacks
ended up being non repairable.
I got some seals from "Martin Fluid Power"
www.mfp.com