Sunex 3-ton floor jack leaks - Rebuild? If so, how? Or toss and replace... but with what?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

1998_K1500_Sub

Nitro Junkie
Supporting Member
Joined
Jan 28, 2019
Messages
2,149
Reaction score
3,250
Location
Rural Illinois
We've got a NAPA 3T floor jack p/n 520-3003 which appears to have been mfg'd by Sunex (pix attached). We've had it... jeez, 20-25yrs maybe.

Lately it's started leaking oil and so it won't lift to full height. Of course we put more oil in it but it leaked out in no time.

Has anyone rebuilt a floor jack... is it reasonably straight-forward?

It appears a rebuild kit is available, but I know nothing about the quality of its parts. Heck, I know nothing about floor jacks but they can't be too complex.


I haven't looked at the cylinder closely to see if it's pitted / rusted, but just guessing I would say "not"... our shop stays reasonably dry, there's no salt tracked into it in the winter, and we leave the cylinder completely retracted (jack "down") when not in use. All the same, I need to check it.

(edit) I haven't checked YouBoob™ to see if anyone's posted a video on this particular jack.
 

Attachments

  • NAPA 520-3003 - dorsal view.jpg
    NAPA 520-3003 - dorsal view.jpg
    782.9 KB · Views: 7
  • NAPA 520-3003 - ventral view.jpg
    NAPA 520-3003 - ventral view.jpg
    782 KB · Views: 7
  • NAPA 3ton jack part no 520-3003.pdf
    836.2 KB · Views: 1
Last edited:

Hipster

I'm Awesome
Joined
Mar 7, 2017
Messages
3,388
Reaction score
5,853
Location
Liberty, NC
The likely hood of finding a rebuild kit might be slim. When I get into stuff like that I usually end up at a heavy equipment hydraulics shop. They usually have boxes and boxes of o-rings and quad-seals metric and sae you can sort through to get what you need. Bring the seals you need to replace and a vernier caliper so you can measure stuff.
 

1998_K1500_Sub

Nitro Junkie
Supporting Member
Joined
Jan 28, 2019
Messages
2,149
Reaction score
3,250
Location
Rural Illinois
Thats a nice old jack. They are a simple bottle jack turned sideways. Go for it!

It is a nice jack.. fast-lift when unloaded, decent lift height, good control when lowering...

I stand nothing to lose by taking it apart. I'm just wondering if it's a bear putting these back together (compressing an O-ring to fit into a cylinder), or if during disassembly there's something that I really should take good notes about so that I can re-assemble (location or orientation of orifices,...).

As usual, I assume the best approach is "take a ton of pictures, measurements and notes."

We've put new cups in hydraulic cylinders before, so sorta "been there done that".


(edit) Found a good video here...

xc_hide_links_from_guests_guests_error_hide_media
 
Last edited:

Hipster

I'm Awesome
Joined
Mar 7, 2017
Messages
3,388
Reaction score
5,853
Location
Liberty, NC
It is a nice jack.. fast-lift when unloaded, decent lift height, good control when lowering...

I stand nothing to lose by taking it apart. I'm just wondering if it's a bear putting these back together (compressing an O-ring to fit into a cylinder), or if during disassembly there's something that I really should take good notes about so that I can re-assemble (location or orientation of orifices,...).

As usual, I assume the best approach is "take a ton of pictures, measurements and notes."

We've put new cups in hydraulic cylinders before, so sorta "been there done that".
It's not that difficult. You want to lubricate everything going back together. I usually check end end of the bores for burrs and clean up with a fine round file followed by a piece of 220-320 grit sandpaper before final clean up if there already isn't a chamfer there. Slide the o-rings down the shafts. Don't roll them.

If you happen to have to split a case and need an oddball gasket you can still buy gasket material in roll form, make a template or use old gasket, and cut a new gasket with a razor knife or exacto.

I have repaired all kinds of stuff like this from porta-power pumps and hydraulic rams I use for work, to outboard trim and Mercruiser trim cylinder's and pumps, bottle jacks etc. for not more than $10-15 dollars worth of o-rings.
 

xXxPARAGONxXx

Supporting Member
Supporting Member
Joined
Nov 27, 2021
Messages
1,311
Reaction score
2,599
Location
Houston, Texas
We've got a NAPA 3T floor jack p/n 520-3003 which appears to have been mfg'd by Sunex (pix attached). We've had it... jeez, 20-25yrs maybe.

Lately it's started leaking oil and so it won't lift to full height. Of course we put more oil in it but it leaked out in no time.

Has anyone rebuilt a floor jack... is it reasonably straight-forward?

It appears a rebuild kit is available, but I know nothing about the quality of its parts. Heck, I know nothing about floor jacks but they can't be too complex.


I haven't looked at the cylinder closely to see if it's pitted / rusted, but just guessing I would say "not"... our shop stays reasonably dry, there's no salt tracked into it in the winter, and we leave the cylinder completely retracted (jack "down") when not in use. All the same, I need to check it.

(edit) I haven't checked YouBoob™ to see if anyone's posted a video on this particular jack.
If a jack is rebuildable, Lazzar’s would likely have a rebuild kit for it.

I had a cheap Chinese built floor jack before. When it came time to rebuild it, it went into the trash. Couldn’t find the part numbers for seals, etc. Of course, this is why they are sold for so cheap. Evidently, one Chinese design is sold by many different manufacturers. They might vary the design slightly (different design of wheels, handle bars), but it’s generally the same.

This time around, got a Hein-Werner HW93652 3-ton hydraulic floor jack for general work, and an ATD ATD-7390 5-ton hydraulic floor jack for behemoth tasks.

Both rebuildable, so basically will never need a new floor jack.

Definitely recommend spending the money to buy a rebuildable jack (again, look at Lazzar’s beforehand to confirm it is rebuildable).

And yeah, if the jack is on its way out, no harm disassembling it. The worst that can happen is that you find it irreparable and have to buy a new one.

Lazzar’s also has great customer service. You can call them; they are very helpful. They also want your business! I left a seal kit in my [website] shopping cart, and they called me a day or so later asking me if I needed any help. I didn’t answer; they left a voicemail. But, I did end up calling back eventually, asking for that salesman, and buying it. He asked me how I knew to ask for him. I told him because of the voicemail.
 
Last edited:

PlayingWithTBI

2022 Truck of the Year
Supporting Member
Joined
Jan 3, 2019
Messages
9,552
Reaction score
14,679
Location
Tonopah, AZ
I haven't rebuilt any floor jacks, I have rebuilt hydraulic cylinders, pumps, and motors. Generally the seal on the shaft is a wiper seal. A good quality cylinder, pump, or motor will have a bushing which the shaft rides on. If the bushing is worn, the seal won't last very long at all. On cheap ones, it's just better to replace the whole thing. Some of them aren't made anymore and kits for our bigger pumps were upwards of $10K for an Oilgear PVV540 so, it's critical to keep everything hospital clean when opening one up! Keep it clean! :waytogo:
 

1998_K1500_Sub

Nitro Junkie
Supporting Member
Joined
Jan 28, 2019
Messages
2,149
Reaction score
3,250
Location
Rural Illinois
Thanks everyone. I'll tear into next week, first opportunity.

We've got a Walker p/n 93662 10-ton jack that's also been leaking a bit of oil. Once I get this NAPA/Sunex jack working I'll tear into the Walker. It's a nice jack... 25" lift, air assist. If someone told me it weighed 300# or more I wouldn't doubt it.
 

thinger2

I'm Awesome
Joined
Jul 6, 2019
Messages
1,562
Reaction score
3,936
Location
Tacoma
My 1950s Walker 4 ton ton air over hydrualic.
This thing is a beast but the air side blew out.
Took it to a hydrualic shop in Tacoma Wa.
They had it for week but they went through the whole thing and rebuilt it for about 400 bucks.
That was at least 15 years ago.
Well worth the money.
I couldnt buy a new one for anywhere near the price of the rebuild.
I know. A 4 ton holding up a bike is just a bit of overkill
 

Attachments

  • 20220513_172849.jpg
    20220513_172849.jpg
    394.6 KB · Views: 8
Top