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Cummins/Onan MJA, MJB, MJC — Water Pump Disassembly

For the Cummins/Onan MJA, MJB, MJC.

Applies to: Cummins Onan Mjc

Procedure

  1. Loosen the pump's end plate screws and remove the end plate.
  2. Pull the impeller and shaft out with a pair of pliers.
  3. If further disassembly is necessary, remove the pump from the engine by loosening the 2 capscrews on its mounting base.
  4. Loosen the set screw on the side of the pump 3 or 4 turns and tap it lightly to free the cam from the pump body.
  5. Lift out the cam and wear plate.
  6. Drive the 2 water seals out from the drive end of the pump. NOTE: Remove these only if they are to be replaced.

Tools required

  • Pliers

Source: manual:968-0500 Onan MJA MJB MJC Service Manual (10-1964).pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.