He pulled the jack apart, and realized that the cylinder was just DOM tubing that had not been honed or ground.
He honed the cylinder carefully with a cheap Harbor Freight cylinder hone (using a drill press), and the pictures show a clear difference before and after honing:
"Normally I use recirculating flood honing fluid to remove the refuse but that wasn't practical in this case because it was a blind hole, so I 3/4 filled the cylinder with fluid to at least get the junk away from the honing surface. It would have been much easier if I had unscrewed the cylinder from the base but it resisted all my efforts to do that."
" I should have mentioned in my original post. that if anyone intends to follow my lead and hone a cylinder still attached to the base, that often there is a valve in the base which stands proud a little. To avoid wrecking that valve you need to ensure that you have a hard stop on the lower end of the hone stroke to prevent it bottoming on the base"
" Baum Hydraulics in Omaha has about any seal made and they are cheap. 800-228-9222 or 9288"
This provided a better surface for the seal, and eliminated the previous sponginess in the jack.
"Next time you need to remove the ram cylinder, put the jack base in a large vice (at least 6"), well anchored to the floor, use a large pipe wrench with a long pipe (36") slid over the handle for more leverage. Finally, put the ram back into the cylinder exactly where you are going to apply the pipe wrench (preferably at the very bottom). Get as close to the bottom as you can since the combination of the cylinder screwed into the base and the ram on the inside will prevent distortion. When you put everything back together, use the same method. The internal pressure of a service jack is around 30,000 PSI so that requires a great deal of torque to seal up."
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