Unscrewed the "DO NOT ADJUST" port from HF Jack (2 tons) - help!

[Debcrow]

I actually did this very same thing with the "Do not" screw on a HF aluminum jack.

I bought the aluminum jack because I got tired of hauling the heavy old steel jack around.
After about a year and a half it started to slowly bleed down after jacking something up. I took all of the valving out of it to see if there was anything gumming up the sealing surfaces when jacking allowing the slow bleed down.
After cleaning all of the surfaces and looking for scoring or damage I could not find any and it still bled down slowly.
OK, I thought, perhaps the overload had something allowing the bleed down. So I marked the screw under the "do not adjust" cap and turned out counting the turns. Everything looked good. Put it back to the place it was. Jack still bled down slowly so I assumed there was a problem with the cylinder seal. At this point I decided the jack was not worth all of the effort I had already put into it. So I decided to test it to destruction to see how it would fail and see what had failed. Took it to work and placed it between two very large structural beams and jacked it as hard as I could. Never failed or bypassed with the amount of pressure I could exert on it...but still slowly bled down.
Tossed the jack in the scrap heap.

 

[jayemm]

With regard to the aluminum harbor freight jack failure that leads us into the difference between “reliability engineering” and “structural safety margins”. It’s certainly possible to design something with beefy safety margins for structural loads and then absolutely screw the pooch on reliability engineering. A company needs to build parts to print, test like they fly, and have a work order process and quality control system to catch deviations from the known good formula. Even if all that happens just perfectly, given a large enough sample size bad things will happen. Six Sigma quality products kill people all day, and it’s the best quality money can buy. Point being it’s way less dangerous than staircases and heart attacks. Someone has to get hit by lightning eventually. Fortunately it sounds like your son didn’t get hurt, basic common sense helps a lot here.

The easy to find internet failure of a HF jack letting go was due to a circular clip popping off a cross shaft attached to the hydraulic ram, allowing two tabs to be liberated as shown below. This is a reliability engineering problem. It is also why PFMEA (process failure mode and effects analysis) is important. Typically something changes like coating thickness, groove cutting tool profile, snap ring supplier, and out pops a new failure mode nobody but Murphy planned for. It wasn’t a structural problem, it was a reliability and quality problem.

Everyone should do what they think is best for themselves. In some possible scenario a guy decides touching the pressure relief screw on his jack was dangerously irresponsible so he falls down the stairs or crashes his car on the way to harbor freight to buy a fresh replacement. Perhaps he tosses out his perfectly reliable steel jack and replaces it with an aluminum one like below, opening up a new failure mode possibility. Also like the single pump design. Lifts to full height in 7-8 pumps.

Personally, I don’t mind the occasional sketchy lift using arborist rope and a bowline knot, but I try to avoid standing directly under it. Some folks are crazy enough to climb K2 when they know it has a 23% mortality rate. Smoke ‘em while you got ‘em and yeah they come with a warning label.

To prevent this I replaced all of the snap rings on my HF US General aluminum jack I bought in 2010. Must say it's been a good jack. Also replaced the soft button head screws with hardened socket head capscrews/ locktite in important locations. Finally took one of the side handles and mounted it in the rear for balanced ease of carrying and painted the side plates blue because I didn't like an all silver jack.

 

[N_Jay]

Great thread. Especially the fear of setting the bypass to just barely lift a vehicle well under the specified limit. (Common sense and safe solution)
There is being careful, and there is poring out a gallon of milk one day after the "Best By" date without a smell or taste.

 

[Hohn]

Watching the fuel filter on a Airbus A320 be replaced wants me to never want to fly again.

You should see how I fixed B-1b fuel systems.

 

[Hohn]

Best read ever, thank you GJ for the entertainment. Lots of good common sense answers here, and a whole bunch of FUD. I’m an actual aerospace engineer who has designed and flown hardware to space. Half the people on this thread would need a change of pants if they knew what type of flaws are acceptable and how skinny the safety factors are for crewed flights. Go have a look at NASA-STD-5012 if you are curious.

For ground hardware like a jack, HF would be crazy to make the metallic structure subject to possible failure at max bypass pressure (screw all in). It probably has at least a 4-to-1 factor on the max rated load. You’re more likely to be injured using the stairs or texting while driving. Maybe lay off the beers in your home shop if you care about safety. Y’all ever worry about heart disease? Use your own judgment, and this isn’t advice or a recommendation. Fu*k it, Fly it boys and girls.

We’re going to be friends, I can tell.

 

[cparke]

I have this same Harbor Freight (HF) 2 ton jack and made this same mistake today, sort of.

The jack in question is pictured and featured in this repair video:

I thought the adjust value was also the fill valve, since the actual fill valve is painted over red and looks like it is just part of the metal like there is no fill valve (HF design style wouldn't surprise me if they did that). However, now I know from the video that there actually is a disguised plug closing it.

I said "sort of" because before opening the adjust valve, I wasn't totally ignorant or stupid of the cap's "Do Not Adjust" warning message. I checked if this was actually an adjust valve first and had a specific position; I found that it was simply screwed in all the way! I've removed and re-inserted it several times, and it always stops at the same turn position as when I first opened it, so I'm pretty sure that was the correct assessment and the original setting. So for this jack, closing it back to the same setting was a no-brainer, which is why I went through with opening it, and I'll bet HF just figured they made the spring weak enough and don't perform any real tests at the factory. That's Harbor Freight for you. Warning of course that other versions or builds of this jack obviously might not be that way.

It also makes sense that I don't think the jack was quite adjusted correctly at the factory either. Now that I've learn from this thread what the adjustment screw is for; I've found at lot of their tools, torque wrenches as another example too, simply do not perform to their specifications and eventually break because of that. I also have their recalled 3 ton jack stands too, probably should get them replaced. They actually honor their lifetime warranty on covered items if you bring them in, but I think many people forget or don't bother and just toss it (I did the same thing at one time).

Finally, further regarding the original adjustment setting on this jack, I have a car listed by the manufacturer's certification of origin at 4750 lbs. This 2-ton floor jack used to be able to lift that, but recently I've noticed leaking and it can't do it anymore, and also the fluid has become black. I was trying to drain and re-fill the jack through the adjustment opening after taking out the ball and spring to fix this, but having back luck getting fluid in and out of course and just gave up and then searched for this thread to learn more about that opening.

I may attempt again to drain the fluid in this jack again, replace the O-rings and refill it to get the experience of restoring it. However, if I find afterwards that this jack can lift that too heavy car again, then I will open the adjustment screw a bit until it can't, and then a little more, making it safer than when it was new. I know now that I need to get a 2.25 ton or better floor jack to lift that car properly, but I should be able to still use it on the other car rated at 3285 lbs, which is also a very low profile vehicle that I got this floor jack for in the first for.

 

[OldDoItAll]

Fireworks are marked "Do not hold in hand" but... how do you get em from one place to another?

 

[racecougar]

Finally, further regarding the original adjustment setting on this jack, I have a car listed by the manufacturer's certification of origin at 4750 lbs. This 2-ton floor jack used to be able to lift that, but recently I've noticed leaking and it can't do it anymore, and also the fluid has become black. I was trying to drain and re-fill the jack through the adjustment opening after taking out the ball and spring to fix this, but having back luck getting fluid in and out of course and just gave up and then searched for this thread to learn more about that opening.

I may attempt again to drain the fluid in this jack again, replace the O-rings and refill it to get the experience of restoring it. However, if I find afterwards that this jack can lift that too heavy car again, then I will open the adjustment screw a bit until it can't, and then a little more, making it safer than when it was new. I know now that I need to get a 2.25 ton or better floor jack to lift that car properly, but I should be able to still use it on the other car rated at 3285 lbs, which is also a very low profile vehicle that I got this floor jack for in the first for.

Aren't you lifting one end or side at a time?

 

[NORTON'S SHOP]

Fireworks are marked "Do not hold in hand" but... how do you get em from one place to another?

Armpit? Numerous orifices that one has on their body? Many workarounds are available.