My Harbor Freight aluminum jack is leaking. I'm assuming it would be best to use Viton O-rings in it when I rebuild it. My question is how do you size the O-rings? Should they be snug on the piston, or should they be a little loose on it?
My Harbor Freight aluminum jack is leaking. I'm assuming it would be best to use Viton O-rings in it when I rebuild it. My question is how do you size the O-rings? Should they be snug on the piston, or should they be a little loose on it?
Don't know for sure but it's a good bet that the "o" rings are square and not true "O" rings.
Are you sure its leaking or has most the fluid gone into the reserve tank?
Sperlo;
It leave a puddle on the floor, so it's leaking out by the piston rod.
jimbbski,
The rings in there now are round cross section O-rings.
I would think you would want it makeing secure contact, without excessive drag, and not loose. But that's just speculation.
Interesting jack rebuilding post. http://garagejournal.com/forum/showthread.php?t=51105
O rings are sized by ID, then cross section.
I've been told that HF (amazingly) has rebuild kits or parts for these. If you look in the back of the manual, they've got diagrams. Wouldn't using cheap probably-not-viton HF parts be in the spirit of buying a "good enough" HF jack in the first place?
I'll have to check with HF and see. I've had this for the best part of 10 years, so I would be surprised if they still have the exact same jack, but it doesn't hurt to ask. I'm trying to figure out how thick the cross section should be compared to the size of the piston groove. Should the cross section be large enough that it goes oval when the piston is pushed in the cylinder, or does the hydraulic pressure push the ring into the corner next the cylinder wall? looking at the Garage Journal thread helps some. My jack has 2 o-ring grooves. one of them is wide enough for the O-ring and a plastic support ring, just like is pictured in that thread.
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