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Hydraulic Spring Tester Bleeding Procedure

Hydraulic Spring Rater - 7306 / 7308

Bleeding procedure after piston/seal replacement


  1. Remove lower slider assembly from frame and place on bench upside down.


  1. Loosen hard line fitting at the gauge 1/2 turn.


  1. Remove piston.


  1. Check condition of cylinder bore. Hone lightly as needed.


  1. If bore is good, fill to approximately 1/4" (6.5mm) from top of cylinder wall. (Marvel Mystery oil is used at the factory, however, any lightweight (10wt) oil will work.)


  1. Place a shop towel or rag under the gauge fitting that was loosened.


  1. Insert the new piston/seal assembly into the bore. (Some coaxing of the seal may be necessary. A ballpoint pen slid slowly around the seal edge works great.)


  1. Push the piston down very slowly. This expels the air from the line out through the loosening fitting at the gauge.


  1. Tighten fitting.


  1. Turn slider assembly right side up and hold at a 45-degree angle with the gauge facing up and loosen fitting.


  1. Using slight upward pressure on the piston, push the piston into bore just enough to expel air in the line. Retighten fitting.


  1. Turn slider upside down again and open fitting at gauge line.


  1. Push piston down to expel any remaining air in the line and then tighten fitting. The piston skirt should protrude from the cylinder approximately 3/8" to 1/2" (9.5-12.7mm).


  1. Test firmness of piston by pushing down with palm of hand. The piston should feel solid with no sponginess. If spongy, repeat bleed procedure. There should be slight movement of the needle with hand pressure.


  1.  Make sure fitting is tight and reassemble spring tester.

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