Engine Hoist Slow Leak - Help me Fix it!

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joe_m

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I have an engine hoist - a rather expensive one, not the red Horror Freight model - that has an invisible leak or something. I used it early in the year to move a 1-ton lathe, no problems at all. Last week I was moving a 200 pound grinder and I noticed that it was very slowly lowering itself as if I had let off the pressure. Problem is, I hadn't let off the pressure. I checked and it was still shut. So with no load I jacked it up so the arm was parallel to the ground and left it overnight (which turned into three days) and when I went back the arm was all the way down on the ground.

There is no hydraulic fluid leaking anywhere. Not a single drop.
BEFORE I moved the lathe I actually dropped it in such a way that the small inner rod came out of the cannister on the shock-absorber looking piece. Some hydraulic fluid leaked out then but I put it back together and it moved the lathe without a problem. Could it be low on fluid or is there maybe something else going on that's causing it to slowly leak inside but not outside? Maybe a problem with the on/off valve (that little knob with the piece of metal you turn with the pipe-shaped "wrench" to let the pressure off)?

thanks
Joe
 
It sounds like the valve is leaking by internally much like when you open the valve using the pipe handle. Have you tried opening the valve a couple of turns and just pumping for a moment, trying to circulate the oil and perhaps flush or dislodge any foreign matter that might be inside? I have a floor jack that does this sometimes and usually I can get it to seal after a few pumps and then re-tighten the valve closed (notice I said usually, not always, as sometimes it gets the best of me). You could of course always disassemble the pump control valve and check it for debris or a cut O-ring.

Good Luck!
 
I'll give it a shot.

I was hoping for something like "Oh, that's simple - just turn that knob to the left while humming the theme from Heavy Metal." :)) But if it doesn't involve buying a new hoist I'll give your method a shot. There may be, probably is, an air bubble in there from when I tipped it over. I'm surprised there isn't a fill valve anywhere - the only two things on that piece are the on/off valve and something with a red cap that says quite clearly DO NOT ADJUST. In my younger days such a bold warning would have been a clear invitation to start fiddling with it, but I've grown wiser and lazier.....
 
Joe, you're throwing me a little with your description of the "small inner rod came out of the cannister on the shock-absorber looking piece." If it is built like the hoists I have seen, there is a long cylinder with the ram extending out of it and connected to the boom. If the ram came out, then there is a problem inside the cylinder, because the ram should be connected to a piston. The piston shouldn't come out of the cylinder.

Got pics?
 
On rams and bottle jacks, a leaking control valve is usually the result of a deformed valve seat. On the imports, that seat is often not the best of materials, and deforms over time. that deformation is accelerated by over-tightening the valve. For that reason, I always treat that valve very gently. Mine seem to last.
I understand on some of the better jacks that seat is replaceable, but I've never torn one down. I expect if it is replaceable, a replacement part can by made by a machinist (that's you). Otherwise, those replacement rams aren't that expensive. Buy a new one and tinker with the old one. Once you have made the original ram into a good spare, you will never need it.

Google "Bottle jack repair" for more info
 
Well I'll try not to embarrass myself by saying the doohickey came off the thingamajig and red koolaid spilled out. :)) Here's a pic.
Normal operation you pump the lever and part A comes up out of part B and lifts the long arm (boom.)

Here's a description of how I broke it. I don't care if you laugh, but don't go telling the rest of the world what I did please, I have a reputation to uphold.
I tried to push the assembled hoist, minus the two long legs, across the desert sands from my garage to my workshop. That was, of course, a stupid move. I hit a rock or maybe a small lizard and it tipped over. When I lifted it, I lifted the long arm (the boom) and not the body. So of course when it was upright and I lifted my arms, I lifted the boom all the way up, pulling part A completely out of part B. At that time part B, no longer being restrained by part A, swung forward. When it reached parallel to the ground the hydraulic fluid started to come out the hole on top where part A used to be. Part A couldn't hold it in because part A was dangling from the boom which was being held up over my head.
So standing there with the boom over my head, part A dangling in the wind, and part B hanging down with red stuff dripping from it, I did the normal thing and reached for part B to try and save the precious hydraulic fluid. Of course that meant releasing the long arm and part A, which was over my head. Luckily I was bending forward to grab part B so when the boom fell it only hit me in the shoulder and upper back. That's about the time that the sands shifted and the entire assembly once again flipped over on its side......

Eventually I managed to grab ahold of part B and hold it semi-upright as I dragged the entire assembly the final 50 feet onto the workshop porch where I was able to walk it back up to vertical. Then I relifted the boom with one hand, propped up part B with my leg, and with the other hand guided part A back into part B as I lowered the boom. It wasn't easy, but I got it reassembled. Then I decided that maybe I should put some more hydraulic fluid in to make up for what was lost. So I dragged the two legs out and put them on (to stabilize it) and once again I lifted the entire boom up - but of course part A wouldn't come out of part B this time. I don't know why, it came out so easily before. So I put it through it's paces with various pieces of junk laying near the porch and it seemed to work. I drove the lathe out to the shop on the traiiler and used the hoist to move it into the shop - no problems with the hoist, so I figured I was safe and just forgot about it until now.

That's my story and I'm sticking to it.
Joe

HOIST.jpg
 
Take out the butterfly shut off valve and see if it is damaged or has a ring in the tapered face. A lil sandpaper to dress uo the valve, a squirt of cleaner to get the particles off, and give er a try. My TSC Hoist will cut a ring if I use the suppled tool, so I just use finger tight, unless I am lifting something heavier. Worth a look, it saved me a time or two.
Bob
 
OH, so that's what you mean! Simply put, "you broke it"!!! LOL

I am surprised to hear the ram actually came out of the jack, I figured there was some kind of a retainer. After hearing this my first thought is you probably now have quite a bit of contamination inside the jack. As suggested you may wish to google how to rebuild the jack and give it a good cleaning and re-fill with clean oil. Of course be prepared to source another jack, just in case!

Good Luck!
 
Joe,
Like Tony I am surprised that there isnt a piston on the end of "shaft A" to prevent that happening. However based on "your story" there a couple of things to go looking for. All of which will require some "fiddling". You could have foreign material in the cylinder possibly damging the seals. you may have damaged the seals when you put "A" back into "B". There may be some debris under the release valve preventing it from seating properly, or damage to the seat. Did you top it up with the correct oil? Start by screwing the release knob all the way out and check for dirt/damage. If the rod came out of the cylinder before it should do so again. Pull that and have a look at the seals. Drop the oil, clean everything spotless, and refill with the specified hydraulic fluid, quite possibly auto transmission fluid based on your "kool-aid" description.

Cheers Phil
 
OK, thanks for all the good tips. I'm pretty sure I didn't get any dirt inside it - the end never dug into the ground and I wiped part off before reinserting. That doesn't mean I didn't damage the seal on that hole though.

I took the suggestion to open the valve and pump a bunch of times. Then I closed the valve and cranked it up until the boom was parallel to the ground. I'll leave it there overnight and measure it in the morning to see if there is a leak.

I never added any more fluid - and I'm guessing on the color because I'm colorblind - because I couldn't get part A to come out of part B again once I inserted it. I did google bottlejack repair (thanks for that suggestion too) and found a tutorial on refilling. Based on that I relooked at the hoist and what I thought was a silver rivet on a silver cylinder turned out to be a silver painted rubber plug about 2/3 up part B, so I'm guessing that's where I can refill it at if need be. Tomorrow when I see how much it's dropped, I'll take out that plug and see if I can tip it enough to get some fluid out, and take that to the auto parts store to make sure I get the right stuff.

The interesting part (to me at least) is that after the impromptu disassembly I was able to use it to lift a lathe with no problem. The leak didn't show up until now - 5 months later.

thanks again for the suggestions.
Joe
 
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