Hydraulic Jack Rebuild Common Questions and Answers.

Ive put this thread together to Essentially Assist in Reducing the amount of Questions that i tend to field over and Over.. via PM/Email or in the General Tool Discussion section. Hopefully this will make it Easier for the Membership to find Answers to some of the More Common Questions. I did gain Permission from the Members on any Linked Thread and sent PM's out to some of the Members who have Knowledge in these Areas and will Add/Associate any Returned info with there Name attached (Trying to keep all the Info on the First Page for Ease of Access). Again.. This is Just a Start, Im still working on some of it.. But Frankly im tired of typing.. Enjoy and Hopefully this will alleviate some of the duplicate Questions that tend to pop up.

Thanks for Reading..

How and Why do i need to bleed my Hydraulic Jack?

Hydraulic Jacks need to be bled on occasion, This can be account of a Low Oil situation allowing Air to be ingested, Heavy Movement which can allow the oil to slosh around in the Reservoir or a Weak or Poor Pump seal that will extrude Oil/Air into the system. A General rule of thumb is 1st make sure there is sufficient oil in the Reservoir, then simply put the jack in the Release position and Pump the Handle 6-8 times. What this will do is make the circuit between the Reservoir, Through the Valve system, Through the Release vein and back into the Reservoir all the time purging the lines from any Air.


How much Oil does my Jack Require?

A general Rule of Thumb is on Floor jacks, The oil should rest aprox 5/16" below the fill hole or rest just above the inner cylinder, when peering thru the hole. On bottle jacks the Fill hole is generally on the Reservoir aprox 3/4 of the way up, It should be filled till oil starts to trickle out of the hole when the jack is in the Upright position. Always Check oil levels with the Jack arm lowered or Bottle jack Ram retracted.

My Jack feels Spongy and is suffering from Poor Lift performance, What to do?

1. Check the Oil level.
2. Bleed if Necessary

Ive Checked the Oil level and Bled the Jack and its still not working correctly.

1. Check for signs of leakage.. This is a Indication that a Seal is or has failed.
2. Unfortunately the Next step requires you to tear into your jack and Inspect the Individual Seals. There are some Tutorials Available to cover some of the Most Popular Models.
3. Typical Import, Yasui/Torin.. Probably makes up the majority of Jacks out there with only subtle changes between Models.
4. Georgia Hybrids 93632 which also covers your 93642/52 etc as a Whole with only Subtle Changes between the models such as type of Seal used (Leather versus Poly) along with Hydraulic unit variations.

Where do i get parts?

There are a Tons of Online Dealers that are willing to Assist you, Check your Phonebook for Local Hydraulic Shop. Its always best to patronize Local businesses in todays Economy. If the Price seems out of line, Dont hesitate to contact me via Pm as i do keep most of the Common sizes in stock.

I removed the Hydraulic unit from the frame, But

1. Now i cant get the Tank Nut off... Grr... Ok first and Foremost, Make sure it is a Threaded Nut, Some Jacks use a Internal C-clip to get to the Ram. If its Threaded The Thread is always been Standard (Lefty Loosey/Righty Tighty). These Tank nuts are Extremely tight, because alot of them (not All) need this torque to seal the Reservoir at both ends (Metal to Metal). First and Foremost, a Proper sized Tool will play dividends, If you dont have the proper sized socket/Wrench you can use a Pipe Wrench on the "Hex" style nuts. It will leave teeth marks, If this bothers you... Go buy the Correct Socket.

2. Next you will need a Vise or Press capable of Holding the Unit while you attempt to unscrew the Nut, Dont be afraid to add Leverage, I keep a 6ft piece of Square tubing that slips over a Breaker bar. I also manufactured a piece that mounts between the floor and the nose of the Unit to keep things on the level while i levy on that cheater bar.

What about this Stinking Overload business

Alot of your Hydraulic Jacks utilize a Safety Overload. It is a Valve that is made up of a Seat/Ball or cone/Heavy Spring with a Adjustment on top.

When you adjust the Plug down it compresses the Spring which in turn adjusts the Seating pressure of the Ball/Cone. All of your seals have a Maximum Operating PSI, When the Overload is properly adjusted it is set to OPEN up when the Cylinder PSI exceeds the Working pressure of the Seal. This Setting will Vary from Jack to Jack, Based off of the Cylinder Bore/Spring Tension etc.. Ive found that over the Years these Heavy springs which are compressed for there entire life lose there tension or Backoff and thus lift prematurely. It takes a specialty Press with a gauge and some minor calculations to properly adjust these.. This is why you shouldnt start blindly turning things. IF you feel the need to get into the Overload during a rebuild, I recommend that you first find out the Current setting by adjusting the Nut completely closed, Taking consideration to count the Revolutions. This way when you go back together you can simply tighten it down and back it off apropriately. LET ME BE CRYSTAL CLEAR... A Hydraulic Jack is Only for Lifting the Load, Once its UP, Make sure you use Jack Stands. NEVER.. NEVER trust your life to a Hydraulic Jack, I dont care what the Brand is, What the Tonnage is etc... JACKSTANDS SAVE LIVES.

Common Signs that the Main Ram as Failed

Generally when you see any Leakage around the Tank nut, This is a good sign that either the Seal has failed or is compromised, Hydraulic Jacks utilize a Seal in the Top end that is supposed to handle any light leakage (Start up leakage). Its not designed to handle High Pressure blow-bye, You also find instances where the Load will Drop over time, Obviously the more severe the seal problem the more Noticable the decent will be.

Why do Seals Fail?

A Hydraulic Seals lifetime is determined by many different factors.

1. Frequency of Use, The More it is used, the Longer it lasts.. Doesnt make sense.. I know, Has to do with Elastomers and keeping them mobile and not prematurely Hardening. <-- Way above my Pay grade.
2. Type of Seal/Material Used, Alot of you Older jacks used HUGE Ucups versus alot of the Smaller ones used today, It seems when combined with Heavy usage those things lasted along time. The Same can be said for Leather Piston Cups.. Ive seen jacks with 40-50 years of service.
3. Condition of the Cylinder of which the Seal is operating, Any Pitting, Imperfections that seal has to Ride against is gonna damage the Lip of the Seal.

What type of Seal is this?

Poly UCUP.. these are Made in Piston/Rod and some that can be used as Either. I generally use the Correct one for whatever application im using.




Leather Piston Cup..

Generally these where used in Older Hydraulic Jacks, But can still be found in Hydraulic Operations today.




Another form of UCup, These where common in alot of your current "Quick Lift Jacks", Im unsure whether its a Poly or BunaN Material, It utilizes a Backup that the Seal actually sits inside and will carry a Ridge on the Actual Ram to accept the Backup (Which has a bigger ID to mate to that Ridge)




Picture of Ram with Ridge..



Probably the Worst Seal that can possibly be used on todays Jacks, Ive found them Very prone to Early Failure. I generally try and replace them with a UCUP. Unfortunatly, Sometimes Minor Metal working is Required.




Leather Vee's, Very common in Walker/lincoln/HW/Blackhawk Jacks and can be found on the Pumps and also on used on the Main Rams. The One pictured is off a variety of Walker/Lincoln/HW Pump Pistons.




And of Course your Typical Oring.. The Majority of Modern Day Jacks utilize them in one form or another, This one is a BunaN material.. Which is fine for the majority of your Needs. Alot of Chatter about Viton being a better selection, The only time i step up to Viton is when used on a Cylinder that is gonna be around alot of Heat, That is Where Viton Shines.. Not to mention its more expensive.



What type of Oil do i need? Where do i get it?

Hydraulic Jack oil can be found at any Auto Parts store, Even Wally World Carries it. If you have a bunch of Bulk Oil laying around ISO 32 is a very similar in Weight, Most of todays Oil all carry the important additives to prevent Rust/Foaming etc... etc.. If you live in Antartica or have a unheated garage, lighter weight oil will help you get things moving. My Grandfather used ATF for a long time.. Back when you could get a quart for .79 cents. LOL... I strictly use Jack oil and i buy in Bulk to save money, I know of NO ill affects from Using ATF.

Why does my Handle on My Floor Jack steadily Rise when under Load

Handle Feedback is a Sign of a Valve Issue, Generally the Upper Ball is not Seating properly and causing High Pressure oil to feedback into the Valve and since the Path to the Reservoir is Blocked by the Lower Ball/Seat it transfer back into the Pump Piston, Which is Connected to your Handle and the Rest is History.

Ball seats? What are you talking about? How do i fix it?

Here is a Good Tutorial about Valve Seats and How they Operate.

If you are having Handle Feedback issue or want to inspect your Seats, You first need to inspect them.. This will Require that you drain the Oil or at Mininnum sway the Oil away from the Valves. Then you must Remove the Balls/Weights/springs etc.. and look for any particles that would prevent the Ball from Seating. Its not always a Bad Seat... Sometimes parts of a Seal (especially a deteriorating seal) will make its way through the system and find itself in between the Ball/Seat.

Procedure for Re-seating the Ball Seat... Insert Proper Sized ball into the Valve, Find a Punch aprox the size of the Ball and "Lightly..I repeat Lightly tap the punch, Remove.. Visibly Inspect, Try the Jack.. Repeat as needed, it is Possible to OVERSEAT. If.. there is substantial Damage or someone has put the wrong components in the Jack and damaged the Seat you need to proceed to the Next step.

Valve Lapping Compound.. and either Buy the Correct Tool or Make your own by using your steady hands and Good eye to center and epoxy the Rod to the Ball as close to center as possible. All this Valve work is done by Hand and you can actually feel the cutting when rotating the stem, Again.. Small Cutting times and Re-inspect... Repeat as needed. Serious Grooves.. will have to be addressed by utilizing Carbide tipper cutting balls or a Machine shop.. If you get to this point.. Sit back and make sure you not gonna invest more than the jack is worth.

Here is a Good Thread where a Member "Jeeper" detailed his Rebuild and Valve work on a Valve Seat.

Piston, Rod Seal WTH are you talking about?

Lets Start First with a Piston Seal.. Basically a Piston Seal is a Seal that is Located on the End of Pump Piston/Ram, The Key Word is End.. When the Pressure hits that Seal it Pushes the Ram Outward. Below is a Picture of Ram (Out of a Napa Jack IRC, Im kinda limited on what i have here at the House to use as Pictures)



This Specific seal is one of the Cheaper Shell/Oring, But it can be a UCUP, Leather Piston Seal or Vee's.

Lets Talk about Rod Seals.. Woot.. You can find Rod seals in tons of Hydraulic Applications, The Material they are made of varies, (Again Limited on Pictures)



Above you will see the Sealing Location and how a "Rod Seal" works. They are Generally recessed into a Groove and seal the Outer portion of a Rod. They can be made up of many Materials including Poly..


buna/Fabrics/Leather injected with many different materials, Below are some Vee's that fit a 10 ton HW.




They Operate similar to a Piston Seal in the Sense that when the Pressure hits the V Or U shaped Channel it expands to allow for a good Seal.

You will also find whats Called a "Backup" on Some Oring Applications, Its Job is to keep the Oring from Distorting under Pressure. You will find these in alot of "Gland" Sealing applications on Hydraulic Cylinders, and on some of your Yasui Based jacks on the Pump Piston. The Majority of the Time they will be on the Backside of the Pressure, Meaning on a Pump Piston the Backup will be on Top to prevent distortion on the Down stroke where its actually moving oil from the Galley to the Cylinder. On occasion you will find Backups on both sides of the Oring. Ive found that you can generally reuse Backups, Unless they are damaged. Pictures below...

Oring with Backup, 1 side of the Backup generally is Flat, the other Concave to accept the apropriate sized Oring.



Oring on top of Backup.



Split Ring Backup, Easier to Install...

Future......

Thats Right.. More Future....

D@mn.. Im tired of typing already..

1 More for Good Luck..

This is great Hiball. Thanks for taking the time to write this up and for all the help you have provided me (directly and indirectly from reading your posts) and other members. GJ is very fortunate to have an expert and willing resource.

I will be installing the rebuild kit I got from you in the (hopefully)near future, I'll be looking here I'm sure...

For those wondering, Hiball can ask this thread to be unlocked and restore the photos if he choses.