Need help with larin floor jack

[psu927]

Bought it an an auction, thinking it worked (40 bucks I know I overpaid) and it lifts with no weight but as soon as you put weight on it it won't lift at all no matter what. Also, as I loosen the release valve with the handle, the valve doesn't stop until the teeth actually disengage. I didn't see if it comes all the way out but don't think it's supposed to do that. What should I do here? It's the 3 ton model and i think it was made in 05.

 

[FoMoCoPower]

We had a Larin forever,it was a good jack,until I loaned it out and it came back severely broken.

 

[sdowney717]

check the pump seals. I repaired a couple of bottle jacks where the o rings were worn. result is it ***** in air instead of oil on every priming up stroke.
So on the downstroke, all it will do is pump air.
Then of course it cant lift any weight. I also use ATF in my jacks.
I bought o rings at autozone and carquest. Napa likely also has o rings.

 

[Pat]

I have had this happen when the jack was just plain low on oil.

 

[psu927]

So I have to tear the assembly apart to get to the seals?

 

[sdowney717]

post a picture. Mostly the pump seal is just pull the pump out of the bore.
Seal is either on the piston pump metal cylinder or in the bore itself. If it is like a bottle jack, it will be just the oring gone bad, not the cup at the end of the piston. Some jack just have multiple orings

 

[Hiball]

Bought it an an auction, thinking it worked (40 bucks I know I overpaid) and it lifts with no weight but as soon as you put weight on it it won't lift at all no matter what. Also, as I loosen the release valve with the handle, the valve doesn't stop until the teeth actually disengage. I didn't see if it comes all the way out but don't think it's supposed to do that. What should I do here? It's the 3 ton model and i think it was made in 05.

More than likely the Overload is the problem, The teeth should never disengage. Check to see that its not missing some teeth or there severly bent. Even with a poor sealing Oring the jack would still work under load if theres no other problems with the valve system. Its far easier to move oil than AIR, Again... Check the Overload. I have a thread stickied at the top that covers the majority of the common import lines.

We had a Larin forever,it was a good jack,until I loaned it out and it came back severely broken.

95% of the jacks that come into my shop all carry the same story, "This jack worked great till i loaned it to a Friend"

 

[sdowney717]

The two bottle jacks and one old Larin floor jack I fixed had worn out o-rings in the pump piston. the Larin was like the bottle jack in design just laid on its side.
There is a cup bolted to pump handle driven piston bottom and a single sealing o-ring higher up.
I theorized that when lifting up the pump piston using the pump handle, air was easier to flow into the piston pumps chamber than thicker oil so it airlocked the ram main lifting piston. Air flowed past the worn oring, the bottom pump piston cup seals tightly only on the down stroke. Replacing the o-rings on all 3 of these made them work great.

I dont know what type of Larin jack he has.

 

[Hiball]

The two bottle jacks and one old Larin floor jack I fixed had worn out o-rings in the pump piston. the Larin was like the bottle jack in design just laid on its side.
There is a cup bolted to piston bottom and a single sealing o-ring higher up.
I theorized that when lifting up the pump piston using the pump handle, air was easier to flow into the piston chamber than thicker oil so it airlocked the piston. Air flowed past the worn oring, the up seals tightly only on the down stroke. Replacing the o-rings on all 3 of these made them work great.

Most of your bottle jacks use a Piston Pump cup, Im sure that larin uses a Rod seal (Oring groove machined inside cylinder) The Orings that is above the Piston Cup on bottle jacks is not used for sealing and used more as a Wiper. Now if your Piston cup is worn to the point where its not doing its job and its relying on the High Oring to pull and push oil its not being used properly and your jack is not working to its full capabilities.

 

[sdowney717]

Maybe they are not working to utmost capability.
I would expect that if the cup on the bottom of the piston was bad, then oil would come out at the top of the pump piston on the downstroke under a heavy load, which I don't see happening.
The cups just looked ok as far as I recall. perhaps they have hardened up some what with age. They do lift up the cars fine. I even lifted the keel of my 17000 lb boat with the 12 ton bottle jack. I was working on the worm shoe and had to move some support blocking.
Dont use pine, use oak. It is quite a site to see pine crushing under heavy load.

 

[Hiball]

Maybe they are not working to utmost capability.
I would expect that if the cup on the bottom of the piston was bad, then oil would come out at the top of the pump piston on the downstroke under a heavy load, which I don't see happening.
The cups just looked ok as far as I recall. perhaps they have hardened up some what with age. They do lift up the cars fine. I even lifted the keel of my 17000 lb boat with the 12 ton bottle jack. I was working on the worm shoe and had to move some support blocking.
Dont use pine, use oak. It is quite a site to see pine crushing under heavy load.

The beauty about Hydraulic jacks, Especially the import lines as they are designed to work sloppy. Even if Oil is bypassing on the Piston cup on the downstroke it still might not be visible because the oring at the top is keeping in down and essentially its not under load unless the Ucup has completely failed. Its another reason i push quality jacks and even imports that utilize Ucups on the Pump or Ram. Even a hardened Ucup will flex outward enough under pressure to minimize blow by under load. A 12 Ton jack should lift 17000lbs without fail if the Ram cup is good and all valves are seating properly as your only at 70% of its rated load.

 

[psu927]

good info guys. I should mention it looks like the jack was never used. It's not scratched and the teeth on the head look like they never saw a car frame. (paint looks almost new). The only sign of wear is the one wheel has a chip out of it. (someone dropped it I guess) Also if it helps, mine is the one that also has the foot pedal for quick lifting. Also looks never used.

 

[sdowney717]

Try this, pump jack up with no load
Put heavy weight on the jack
Does the jack drop back down?
Take weight off jack, does it pop back up, does it act like a spring?

 

[psu927]

145 lb weight jumping on it no bounce.

 

[sdowney717]

well, I was thinking more like 1500 lbs or the rated capacity to see it the relief overflow valve was a problem. I think the way this works is to keep you from lifting more weight than the jack is made to lift, and if the weight on the jack exceeds a certain value to keep it from being crushed. So it has a relief valve that just lets the oil flow out of the lifting ram. You just dont weigh enough to test it.

I would guess if that valve was adjusted wrongly, then when you put a very heavy weight on the jack, it would steadily lower down.

It appears there is no air in the jack cause then it would be spongy.

 

[Hiball]

145 lb weight jumping on it no bounce.

well, I was thinking more like 1500 lbs or the rated capacity to see it the relief overflow valve was a problem. I think the way this works is to keep you from lifting more weight than the jack is made to lift, and if the weight on the jack exceeds a certain value to keep it from being crushed. So it has a relief valve that just lets the oil flow out of the lifting ram. You just dont weigh enough to test it.

I would guess if that valve was adjusted wrongly, then when you put a very heavy weight on the jack, it would steadily lower down.

It appears there is no air in the jack cause then it would be spongy.

Man you guys are killing Me, pull the Overload Valve and count the revolutions from its position to completely closed, Let me know what it is. IF you unable to determine which valve is the overload, Take a picture and post it up. This is the first place you need to look, IF no problems are found you will have to tear into the jack.

 

[GeorgiaHybrid]

The two bottle jacks and one old Larin floor jack I fixed had worn out o-rings in the pump piston.

Just thought I would let you know, Hiball has probably fixed more jacks this morning than you have in your entire career. You might want to listen to what he is saying....

 

[sdowney717]

Yeah, I figured that out earlier. But listening about what?
My jacks are all working now. Changing the o rings made them work. I agree the cups are likely worn and dont seal as good as when new, but they are likely difficult to find.

 

[Hiball]

Yeah, I figured that out earlier. But listening about what?
My jacks are all working now. Changing the o rings made them work. I agree the cups are likely worn and dont seal as good as when new, but they are likely difficult to find.

No Worries, Im sure the OP is thankful for your help and i can respect anyone who tries to fix there problems instead of junking them and buying new. Im only cutting out the trial and error methods you've discussed and trying to point the OP in the correct direction to remedy his problem as quickly as possible. BTW those piston cups are readily available.

 

[psu927]

I'll tear into it this soon and post an update