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Rebuilding a hydraulic Jack... cornfuzed..


Rogan

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Nope, I don't have a manual, and I don't know wtf I'm doing. All I can say is that it works when it wants, and that's not good enough.

Its a Central Hydraulics motorcycle Jack.

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It doesn't leak, and it appears to be full of fluid. However, I don't know what all these are for:

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Left side, no idea. Allen plug pukes oil when I open it. Right flat tip screw thingy when you take it out has a flat tip screw adjuster inside.

Any help? Sometimes the Jack works full stroke pump. Sometimes, partial stroke. Sometimes it doesn't hardly move.

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A simple way to blead most jacks is to leave it in the lower or released position with the valve open and then pump it for a while. This will usually cycle the air out of the valve. Works on a lot of jacks and pumps but not gauranteeing it would work on all.

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Manual hydraulic jacks are pretty simple creatures. It'd be easier if we had X-ray vision. You have a reservoir. You have a pump which draws oil from the reservoir & forces it through a check valve into the piston cylinder. You have a release which is nothing more than a bypass from the cylinder back into the reservoir. If it lifts & holds & releases when you turn the handle, then that part is ok.If there's oil in the reservoir, that should be all that required.It is possible to blow the O-rings out of the cylinders but that's pretty obivious under load. I used to blow the seals out of jacks jacking up boat cradles... with 40 foot Concordia yawls in them! The yard sent them out to be "rebuilt" but I don't think the did anything more than add oil.The pump... there could be a blown seal in the pump. My brother has had some luck matching O rings at the auto parts or hardware store by trial & error... he says something about jacking up train engines is tough on jacks. There could be something wrong with the check valve.

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I read it, once I found it online. Still, though, it doesn't really break down what I need broken down to troubleshoot. I think it's all in the cylinder assembly, maybe a piece of trash or something in the fluid that occasionally doesn't allow the valve to close completely.. I dunno..

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