I rebuilt this old sears jack (made in US) when lift my truck I would day it lifts the vehicle 25% of maximum, then stops even though I am pumping. I have rechecked the fluid level now actually have too much in it but no changes . I appreciate any ideas, thanks
Sears jack will lift vehicle partially then stop
- Thread starter vmaxman61
- Start date
firebirdparts
Well-known member
Generally, they quit when the fluid runs out. if you're sure that's not the case, then you should assume it quits when the relief valve opens. Maybe there's a third option, somebody else can give that.
BillK
Well-known member
Cycle it all the way up and down a few times with no load on it and see what happens.
My guess is it's low on fluid or it needs bled out.
Spareparts
Well-known member
When all the way down the resovior should be full, like was posted before cycle it up and down a few times
with the fill cap off to relieve the air. Sounds like it has air in it.
with the fill cap off to relieve the air. Sounds like it has air in it.
Spareparts
Well-known member
Their was a guy on here that rebuilt/restored jacks forgot his name, maybe someone here remember's name.
Thomas on restored 30's shop might remember.
Thomas on restored 30's shop might remember.
isb cornbinder
Well-known member
A few of the floorjack I freshened up had scoring in the cylinder barrel. Sometimes the piston seals will work over the damage. This sounds like your jack has a leak-back situation.
I would caution using this jack until it is totally right. My friend spent the rest of his shortened life in a wheelchair in assisted living when a repaired jack failed and crushed him.
I would caution using this jack until it is totally right. My friend spent the rest of his shortened life in a wheelchair in assisted living when a repaired jack failed and crushed him.
Rst277
Well-known member
Never trust any jack! Use the jack stands!
In regards to the issue how would you address it? Rebuild and hone cylinder? As I recall the cylinder wall looked great but I believe what your suggesting is the issue
isb cornbinder
Well-known member
One of the guys I worked with put a cylinder seal in backwards. The tailgate lift made a feeble effort to lift and failed a few centimeters off the floor. I don't think this is your problem, but check anyway.. My son had the brakes done at a local brake and muffler shop. The Technician put the brake piston seals in backward. My son applied the brakes and his vehicle rolled through a redlight. This was 20 years ago.
This is not your problem, but an example of a bad modification.
I understand wanting to restore a jack. There are costs and liabilities. Keep the low cost of a new jack in mind.
I did a near perfect job of restoring my floor jack. BUT, it would not lift my 1940 Ford rear axle. I discovered that the jack handle had bee shortened by 20 inches. i added 2 feet of length and suddenly the jack worked., it was all mechanical advantage. that was lost.
This is not your problem, but an example of a bad modification.
I understand wanting to restore a jack. There are costs and liabilities. Keep the low cost of a new jack in mind.
I did a near perfect job of restoring my floor jack. BUT, it would not lift my 1940 Ford rear axle. I discovered that the jack handle had bee shortened by 20 inches. i added 2 feet of length and suddenly the jack worked., it was all mechanical advantage. that was lost.
Attachments
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Hydraulic Jack Rebuild Common Questions and Answers.
Ive put this thread together to Essentially Assist in Reducing the amount of Questions that i tend to field over and Over.. via PM/Email or in the General Tool Discussion section. Hopefully this will make it Easier for the Membership to find Answers to some of the More Common Questions. I did...
www.garagejournal.com
that would be Hiball: I believe he also posted some step-by-step rebuild threads.
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Thanks I have confirmed fluid issues by bleeding and refilling without any change. The jack will only raise approximately 25% of capacity , again this is after a rebuild. There are no leaks. As mentioned I did tighten the overload screw before disassembly to determine overload setting. At this point I may have to tear it down and recheck seals. Before doing that is it worth rechecking the overload screw? I suppose just to be sure that I did not set it correctly? At this point I do have the metal caps in place but I suppose worth the effort to recheck
dfiler2
Well-known member
When you say 25% of capacity, do you mean for height or weight?
bluedog225
Well-known member
There is also jack oil with leak stop. May get more life out of old jacks.
isb cornbinder
Well-known member
Jack oil may be an opportunity to rename ATF. ATF is inexpensive. Jack oil, may be a lot more.
The very large company I worked in, for 35 years, used ATF for all hydraulics, including air tool lube.
We had IR big impacts, some over 20 years old. These impacts served more time than any 50 DIY guys would in the same 20 years. Be an informed consumer. Be careful of a situation that does not exist and a cure in a bottle fix.
On the subject of leak down, if there is a leak, it may be bi-passing the piston seal and not appearing outside of the cylinder.
I have seen apprentices put the piston seal on backward because it made assembly easier.
bluedog225
Well-known member
A fiver w for 12 ounces. Delivered.
I have disassembled the jack to be sure all parts were in correctly and they were. I will preface this to say that I did not however disassemble the pump valve. The pump still lifts approximately 25% of height then it will not lift any high but the pump works and it seems like I am pumping air. I would appreciate any other ideas. The rams seal is NOT leaking period, Can it be leaking around the pump valve? Ideas are greatly appreciated