Rebuilding a Hydraulic Floor Jack

Step 10: Clean the bottle jack unit's passageways

The first photo shows a paper towel I pressed into the cylinder and rotated with a screwdriver without letting the screwdriver touch the sides of the cylinder. (Be careful not to scratch the inside of the cylinder.  A 1/2 inch dowel pin would have been a safer tool to use.)  Jack fluid is clear.  The towel shows how much dirt was in my jack's oil.  In addition to sopping up some dirty oil still in the cylinder, I poured a little clean jack oil into the openings and passageways.  Most of it collected in the opening for the plunger.  At first this oil was cloudy. After a few tries, it was clear. I think this should adequately clean the jack so that it can be reassembled. 

Inspect the seats in the bottle jack unit's body for signs of rust and pitting.  The seats need to be clean and smooth.  When I let sunlight shine into the recesses where there are seats, I saw more dirt.  I used a wooden dowel rod to scrape and break loose any dirt I could find.  I poured some jack oil into the holes to flush the dirt away. 

Second photo--Clean the groove that receives the tank's outer shell. It has some brown dried oil residue. Something brass would be ideal.  It would be tough enough to remove the residue, but would not scratch the machined surface. Someone said jack oil is a vegetable oil. The oil residue is certainly like what I have seen in the kitchen from vegetable oils.