How to Rebuild a Sea Water Pump on an 8.1 Mercruiser 2002 Cobalt 246

The 2002 model year Mercruiser 8.1 L Cobalt 246 marine engine has both a closed cooling system that carries heat from the engine, and a seawater system that carries the heat away from the closed cooling system. There's an oddity, though -- the seawater pump is the borrowed from the Mercruiser 6.2 L gasoline engine, with which it shares the idea of using seawater to cool the coolant. The process to rebuild the system requires you do no more than remove the pump, replace the parts that need replacement and put the pump back into place.

Things You'll Need

  • Gear puller
  • 13 mm socket
  • Seawater pump repair kit
  • Flat tray
  • Solvent cleaner
  • Air compressor
  • Seawater pump pulley
  • Engine oil
  • Thread locking adhesive
  • Clean cloth
  • Soapy water
  • Torque driver
  • Foot-pound torque wrench
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Instructions

  1. Removal and Rejuvenation

    • 1

      Loosen the hose clamps and remove the two hoses from the back of the pump, using a flat-head screwdriver. Tag the hoses, so you can identify them during reinstallation. Remove the serpentine belt from the seawater pump pulley.

    • 2

      Attach a gear puller to the pulley. Turn the central screw of the gear puller to press the pulley from the shaft. Remove the six bolts from the back of the seawater pump using a 13 mm socket.

    • 3

      Remove and discard the O-ring on the pump's back plate. Remove the seawater pump bearing housing. Remove the impeller. Remove the retainer from the front of the pump shaft. Remove the retainer ring that holds the pump shaft and rear oil seal in place. Press the bearing shaft out of the housing, from the impeller side. Remove the rear oil seal from the housing.

    • 4

      Submerge the metal parts -- the bearing housing, the shaft and the pump bearing housing -- in a flat tray filled with a solvent cleaner. Scrape any gasket material or gasket sealer from the sealing surfaces of the pump parts. Blow dry the pump parts with compressed air.

    • 5

      Inspect the bearing housing surfaces where the bearings come in contact with the housing, for evidence of the bearing outer races turning within the housing. Inspect and, if necessary, replace the seals in the bearing housing and pump body with parts from the seawater pump replacement kit. Inspect the pump body for cracks.

    • 6

      Inspect the sides of the impeller for wear on the tips of the blades and cracks. If there are cracks in the impeller blades, or if the blades are "set" in a curved position, replace the impeller. Turn the pump pulley over and look for excessive wear. Replace the pulley, if needed

    Reinstallation

    • 7

      Place the rear oil seal into the bearing shaft housing so that the side that has the spring is toward the main pump body. Lubricate the bearing shaft assembly with engine oil.

    • 8

      Slip the tolerance ring on to the shaft and press into the small end of the pump. Apply a thread-locking adhesive to the outer edge of the ring. Place the retainer seal on the shaft and press it firmly into place in the small end of the pump body. Wipe away any excess adhesive with a clean cloth.

    • 9

      Lubricate the impeller with soapy water and push the impeller into place in the pump housing. Install the O-ring into the groove on the large end of the pump body. Align the pump body with the screw holes on the pump back plate and thread the six screws into place by hand.

    • 10

      Tighten the screws to 88 inch-pounds with a torque driver. Bolt the seawater pump and bracket to the engine. Install the four bolts, tightening them to 30 foot-pounds with a foot-pound torque wrench.

    • 11

      Attach the hoses to the back side of the seawater pump, using the hose clamps. Tighten the clamps securely. Press the pulley onto the pump shaft and reinstall the serpentine belt.