Leaking Craftsman 3.5 ton floor jack

[stanward]

Hello,

I have a leaking 3.5 ton Craftsman Floor Jack that I really do not want to get rid of. Here are the steps in me trying to repair it:

1. Purchased corresponding seal kit from Shinn Fu America and installed.
2. Jack still leaked so left it on the side for 1 year.
3. Want to resurrect the beast, so I tried changing the one o-ring for the ram to see if that helped. No it did not.
4. Noticed scratches on the ram (used floor jack on gravel, gravel scratched the ram heavily which originally caused the leak)
5. Polished the scratches off of the ram to a mirror finish
6. Jack still leaked, believe it is due to over filling of the hydraulic fluid. Purged some out.
7. Jack does not leak when ram is all the way IN (saddle all the way down).
8. Jack does not leak when ram is half-way OUT (saddle at mid-level).
9. Jack leaked when ram is all the way OUT (saddle at highest point).

I tested steps 7, 8, and 9 overnight each time to give it time to leak.

The jack is not overfilled with hydraulic fluid. I think it is a bit underfilled if anything.

Please help! I really like this particular jack.

Stan

 

[Hiball]

Have you verified 100% where the leak is coming from? Hydraulic Oil can do funny things, The leak can start at one end and fool you into thinking its leaking at the other. When you rebuilt the Jack did you remove the Cylinder from the Base?

 

[stanward]

Hello Hiball,

Thank you for responding. Just as an FYI, I did read thru the entire FAQ that you made for leaking floor jacks.

I did confirm 100% that it is leaking at the o-ring seal between the locking nut and the ram. When I tilt the jack over, I can see the jack leaking oil too!

What is the "cylinder" that you're talking about? Is it the main body of the power unit that has a large o-ring on each end?

I did change both large O-rings. I do lubricate the O-rings with hydraulic jack oil upon installation, as I don't want to tear the O-rings.

I notice when I remove the oil fill plug, there is a lot of air pressure built-up in the power unit. Does this mean one of the O-rings is sucking in air? Is this built-up air pressure causing the leak (pushing oil thru the leaking o-ring?

Please help!

Stan

Have you verified 100% where the leak is coming from? Hydraulic Oil can do funny things, The leak can start at one end and fool you into thinking its leaking at the other. When you rebuilt the Jack did you remove the Cylinder from the Base?

 

[stanward]

Here is a photo showing the power unit and where it is leaking.

 

[Hiball]

Hello Hiball,

Thank you for responding. Just as an FYI, I did read thru the entire FAQ that you made for leaking floor jacks.

I did confirm 100% that it is leaking at the o-ring seal between the locking nut and the ram. When I tilt the jack over, I can see the jack leaking oil too!

What is the "cylinder" that you're talking about? Is it the main body of the power unit that has a large o-ring on each end?

I did change both large O-rings. I do lubricate the O-rings with hydraulic jack oil upon installation, as I don't want to tear the O-rings.

I notice when I remove the oil fill plug, there is a lot of air pressure built-up in the power unit. Does this mean one of the O-rings is sucking in air? Is this built-up air pressure causing the leak (pushing oil thru the leaking o-ring?

Please help!

Stan

Any Oil that shows up there is bypassing by on the Main Ram seal, When you rebuilt the Jack previously did you replace the Main Seal? Was is a Standard ucup? Shell/Oring or the Ucup with the Backup (see Picture)





Did you notice any issues with the Cylinder? gouges? Was the fitment good?

The Cylinder is the piece that threads into the Block, I suspect your referencing the Reservoir, Which is the part that is sealed on both ends via Oring on the Base/Tank nut.

The Best case scenario is a very smooth polished Ram, This way the Oring inside the Tank nut can seal any Oil that does happen to pass the Main Ram Seal, But.. if the Cylinder wall is Good, Proper sized Seal is used.. You should have very little blow-by outside of the Over Extension cutouts.

Reservoir Pressure is Normal, This is why you Don't completely fill Reservoirs account there needs to be Head space to control the Air as the oil is pumped from Reservoir to Cylinder and also when the Oil returns upon the Release.

Is this a Quick Lift Jack?

 

[stanward]

Yes, I replaced the main ram seal. It is the ucup (blue in color) you show (I don't remember if it had a backup or not), and is a quick-lift jack (reason why I like this jack so much). The fitment was good between the ram and the cylinder. I called ShinnFu to order another seal kit for this jack, but they are all out of stock and I need to wait until the 13th of this month.

I can take it apart and inspect the cylinder wall again.

With the saddle all the way down, the oil is leaking at the tank-nut o-ring.

I remember this happening before when I first rebuilt this jack, the O-rings wouldn't leak the first time I use it, but once it leaked, the oil kept dripping out. What does this mean?

I did polish the ram to a mirror finish.

Any Oil that shows up there is bypassing by on the Main Ram seal, When you rebuilt the Jack previously did you replace the Main Seal? Was is a Standard ucup? Shell/Oring or the Ucup with the Backup (see Picture)





Did you notice any issues with the Cylinder? gouges? Was the fitment good?

The Cylinder is the piece that threads into the Block, I suspect your referencing the Reservoir, Which is the part that is sealed on both ends via Oring on the Base/Tank nut.

The Best case scenario is a very smooth polished Ram, This way the Oring inside the Tank nut can seal any Oil that does happen to pass the Main Ram Seal, But.. if the Cylinder wall is Good, Proper sized Seal is used.. You should have very little blow-by.

Reservoir Pressure is Normal, This is why you Don't completely fill Reservoirs account there needs to be Head space to control the Air as the oil is pumped from Reservoir to Cylinder and also when the Oil returns upon the Release.

Is this a Quick Lift Jack?

 

[Hiball]

Yes, I replaced the main ram seal. It is the ucup (blue in color) you show (I don't remember if it had a backup or not), and is a quick-lift jack (reason why I like this jack so much). The fitment was good between the ram and the cylinder. I called ShinnFu to order another seal kit for this jack, but they are all out of stock and I need to wait until the 13th of this month.

I can take it apart and inspect the cylinder wall again.

With the saddle all the way down, the oil is leaking at the tank-nut o-ring.

I remember this happening before when I first rebuilt this jack, the O-rings wouldn't leak the first time I use it, but once it leaked, the oil kept dripping out. What does this mean?

I did polish the ram to a mirror finish.

If Oil is getting "On top" of the Ucup due to Poor fitting etc.. it will allow oil to accumulate there, But if you have the Proper sized oring and a good finish on the Rod Portion of the ram, it should control any Non pressurized oil which would be what you have with the Lift arm Down. I asked earlier if you removed the Cylinder, The Reason I asked is if your not careful you can "Flat Spot" the Cylinder when removing and this will definitely cause sealing issues when the Ucup reaches that area. At this Point If your 100% sure the oil is coming from the portion between the Ram/Inner tank nut seal, Its time to dismantle and snap some pictures of the Seal, How its sitting etc..

 

[stanward]

I haven't removed the cylinder. I only removed the reservoir and the ram itself.

I haven't done a complete rebuild (sorry if I mislead you), as I have some white plastic rings from the kit that I don't know where they go.

I will take the power unit apart again and take some pictures later tonight.

Thank you!

 

[Hiball]

I haven't removed the cylinder. I only removed the reservoir and the ram itself.

I haven't done a complete rebuild (sorry if I mislead you), as I have some white plastic rings from the kit that I don't know where they go.

I will take the power unit apart again and take some pictures later tonight.

Thank you!

IRC there should be a Oring with a mated backup under the Cylinder where it threads into the block. Maybe some pictures of what you have left? Does the Quick lift still work as it should?

 

[stanward]

Thank you for being so patient with me. I don't understand how a hydraulic bottle jack works, so most of this terminology is new to me.

I have attached the extra parts. This jack does have a backup to the ucup (I checked the exploded parts view pdf file from ShinnFu).

http://www.shinnfuamerica.com/ProductDetails/Omega_Lift_Equipment/Magic_Lift_Service_Jacks/25030/360

 

[Hiball]

Thank you for being so patient with me. I don't understand how a hydraulic bottle jack works, so most of this terminology is new to me.

I have attached the extra parts. This jack does have a backup to the ucup (I checked the exploded parts view pdf file from ShinnFu).

http://www.shinnfuamerica.com/ProductDetails/Omega_Lift_Equipment/Magic_Lift_Service_Jacks/25030/360

Those little fat Orings are for the Valves, Did you change the Orings in in the End of the Ram for the Quick Lift? Looks like there are some of them, Possibly Pump Seals? And im Not 100% familiar with Shinn fu kits, there may be extra pieces for different series etc..

What did you replace?

 

[stanward]

I replaced both large O-rings for the reservoir, the o-ring for the large case nut. I replaced the ucup and backup. I also replaced the small o-ring in the piston that pumps from the handle.

I noticed the ram is damaged. I circled it in red in one of the photos below.

I'm thinking I may have damaged it when I replaced the ucup and backup. I don't remember.

 

[Hiball]

I replaced both large O-rings for the reservoir, the o-ring for the large case nut. I replaced the ucup and backup. I also replaced the small o-ring in the piston that pumps from the handle.

I noticed the ram is damaged. I circled it in red in one of the photos below.

I'm thinking I may have damaged it when I replaced the ucup and backup. I don't remember.

Pull the Snap Ring so I can see the ID fitment of the Ucup, Then remove the Ucup, Backup and Guide and take some pictures. What is that material that you circled? Metal shavings? Do you see any gauges in the Cylinder? Any Marks on the flared portion of the Ucup?

The 3 grooves you see in the Cylinder Wall are there to stop the Ram from Over extending, When the Seal hits that area under load it allows it to bypass. If you look inside the Tank Nut there probably is a weep hole that gives the oil a path back into the reservoir. I would pull the Tank Seal (The one inside the Nut/Part number "I") and verify that its sealing the rod portion of the Ram correctly.

 

[stanward]

The "metal shavings" I circled is not shavings, it's gouges in the ram because I had a hard time taking the ucup off of the ram.

I had a hard time taking off the ucup and stuff, instead of using a hammer and chisel, I used my shop press.

The ucup is very tight on the ram!!!!!

 

[stanward]

Sorry, I failed to reply to your questions.

I don't see any gouges in the cylinder. The flared portion of the ucup looks very good, no gouges or scratches there.

The metal round piece after the backup ucup looks scraped.

 

[Hiball]

The "metal shavings" I circled is not shavings, it's gouges in the ram because I had a hard time taking the ucup off of the ram.

I had a hard time taking off the ucup and stuff, instead of using a hammer and chisel, I used my shop press.

The ucup is very tight on the ram!!!!!

Its Hard to say... Can you rotate the Seal by hand when its on the Ram? It shouldn't be that difficult to remove, But doesn't appear to be flared inward on the Face and the OD looks good. What are the measurements on the Back up the Ucup? Do you have a caliper to measure the Ram where the Ucup sits (ID)?

 

[Hiball]

Sorry, I failed to reply to your questions.

I don't see any gouges in the cylinder. The flared portion of the ucup looks very good, no gouges or scratches there.

The metal round piece after the backup ucup looks scraped.

Yeah I seen that.

I will say this.. That Ram doesn't have a very clean surface for the UCup to seal against on the ID, Looks Rough.

 

[stanward]

Its Hard to say... Can you rotate the Seal by hand when its on the Ram? It shouldn't be that difficult to remove, But doesn't appear to be flared inward on the Face and the OD looks good. What are the measurements on the Back up the Ucup? Do you have a caliper to measure the Ram where the Ucup sits (ID)?

I can measure where the ucup seal sits (0.969").

The diameter where the metal cylinder sits (is it a backup u-cup?) is 1.015".

When the ucup is on the ram, I can spin it by hand. But to remove the ucup from the ram is another story. I couldn't pull it off.

 

[Hiball]

I can measure where the ucup seal sits (0.969").

The diameter where the metal cylinder sits (is it a backup u-cup?) is 1.015".

When the ucup is on the ram, I can spin it by hand. But to remove the ucup from the ram is another story. I couldn't pull it off.

And what kind of measurement do you get from the Actual Ucup on the "bottom side" ID?

Im guessing that's a 24MM x 40MM cup, Which should measure roughly 24.5MM on the bottom side ID.

 

[stanward]

Blue ucup measurements:
ID: 0.981"
flared ID: 0.906"

OD: 1.569"
flared OD: 1.6"

 

[Hiball]

Blue ucup measurements:
ID: 0.981"
flared ID: 0.906"

OD: 1.569"
flared OD: 1.6"

Hmm.. I would double check the Oring inside the Tank nut, Remove it and check the fitment on the Ram itself. Prior to removing it.. Look inside and make sure the Oring has a portion of its sealing surface "Outside" of the Groove. Maybe the wrong Cross Section? Dunno its difficult to diagnose over the internet.

 

[stanward]

Hmm.. I would double check the Oring inside the Tank nut, Remove it and check the fitment on the Ram itself. Prior to removing it.. Look inside and make sure the Oring has a portion of its sealing surface "Outside" of the Groove. Maybe the wrong Cross Section? Dunno its difficult to diagnose over the internet.

You are right, I checked the fitment of the o-ring and it doesn't have a proper fit. The cross section of the o-ring is too small.

I will be ordering new O-rings from The O-ring Store (you can buy small quantities and they have a generous selection).

Thank you for your help!

Stan

 

[Hiball]

You are right, I checked the fitment of the o-ring and it doesn't have a proper fit. The cross section of the o-ring is too small.

I will be ordering new O-rings from The O-ring Store (you can buy small quantities and they have a generous selection).

Thank you for your help!

Stan

Very good..

 

[stanward]

I finally got around to installing the new o-ring I bought from The O-Ring Store.

So far, the floor jack hasn't leaked (replaced the o-ring last week).

Thank you for your help in this.

Stan