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How to replace an oil seal in Models 600, 1500 series, 515 and 626 - WKB4299

Article number: 4299


To remove the old oil seals and replace them with new ones.


  • 600 Pump MultiSolvent Delivery System
  • 1515 HPLC Pump
  • 1525 EF HPLC Pump
  • 1525 Micro HPLC Pump
  • 515 HPLC Pump
  • 626 LC System
  • 6000A Pump


Tools Required: 5/16" wrench, 5/22" hex wrench, 9/64" hex wrench, snap-ring pliers, plunger insertion tool, medium-size flat-blade screwdriver, 13/16" spark plug socket.


  1. Remove pump head, head support, and plunger as described in the maintenance section of the operator's manual.
  2. Set flow to .5ml/min. When piston reaches the innermost position, turn flow off.
  3. Insert the medium-size flat-blade screwdriver between the piston and the inner edge of oil seal. CAUTION: Do not use excessive force when inserting screwdriver as this may result in damage to the brass bushing situated behind the oil seal.
  4. Brace the shaft of the screwdriver against the piston. Using the screwdriver as a lever, attempt to pry up the oil seal while simultaneously twisting the handle of the screwdriver.
  5. Keeping the screwdriver blade under the oil seal and the screwdriver shaft braced against the piston, set the flow to .5ml/min. As the piston begins to move forward, it will pull the oil seal forward. When the piston retracts, reach in and remove the oil seal.
  6. NOTE: Repeat steps 3, 4 and 5 until the oil seal is removed.


  1. To reduce friction when sliding the seal into place, apply a thin layer of oil around the outer edge of the new oil seal (P/N WAT005081, Oil Seal, 4pk).
  2. Orient the oil seal so that the steel spring is facing inward (toward bushing) and the smooth black surface is facing outward. Begin sliding the oil seal into the casting.
  3. Use a 13/16" spark plug socket to slide the oil seal completely into the casting until it will move no further and makes contact with the bushing situation behind the seal. The piston should extend beyond the oil seal when the seal is seated correctly.
  4. Reinstall the plunger, head support, and pump head as described in the maintenance section of the operator's manual.


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