sears floor jack 328-12040

[Coreo19]

new to the forums but have been reading threads here for a while.

I recently bought a old sears 2 ton floor jack model # 328.12040 made in japan. the jack will lift up a car fine but will leak down in about 3 minutes. I have read just about every thread hiball has made concerning floor jacks but I am still stumped.
I assumed the jack was leaking through either the check valves one big steel ball with a little steel ball under it or through the release valve. I pulled all 3 balls out and inspected the balls and its seat pretty close and could not find anything wrong with either. the overload was set 1 turn out ( well within spec from what I have read).

my question is can fluid be leaking past the main ram seal without leaking fluid outside the ram and onto the floor?

thanks for any help you can give me!

 

[Hiball]

new to the forums but have been reading threads here for a while.

I recently bought a old sears 2 ton floor jack model # 328.12040 made in japan. the jack will lift up a car fine but will leak down in about 3 minutes. I have read just about every thread hiball has made concerning floor jacks but I am still stumped.
I assumed the jack was leaking through either the check valves one big steel ball with a little steel ball under it or through the release valve. I pulled all 3 balls out and inspected the balls and its seat pretty close and could not find anything wrong with either. the overload was set 1 turn out ( well within spec from what I have read).

my question is can fluid be leaking past the main ram seal without leaking fluid outside the ram and onto the floor?

thanks for any help you can give me!

Absolutely.

 

[Maui]

I have an old sears Craftsman floor jack and jack stands that I bought as a set back in college over 25 years ago for working on my car. It still works just fine. But it will slowly loose pressure if I leave it under load long enough (over an hour or so). And it doesn't leak a drop on the floor. So my guess is that yours is doing the same thing, just much faster.

 

[Coreo19]

Correct. Mine is leaking down within 1-3 minutes. Regardless of how much weight is on it.

Hiball-thanks for the quick reply. I will try rebuilding it then.

 

[mike5511]

Old thread I know, but has anybody tried just replaceing the o-ring that is leaking without buying the whole kit? I have the same model as the O.P. Sears 328.12040.

 

[Hiball]

Old thread I know, but has anybody tried just replaceing the o-ring that is leaking without buying the whole kit? I have the same model as the O.P. Sears 328.12040.

While I’m not a fan of replacing individual components, especially when talking about seals that require a complete tear down to get to anyways. If your referencing the pump rod seal, which doesn’t require a complete tear down, I suppose it’s OK, but if warranted I would rather see all seals replaced, this way you know what you have.

If it’s $$$ issue, learn how to measure seals and save some money. The majority of people selling these Sears Yasui jacks kits are operating at considerable markups.