Cummins/Onan — Sea Water Pump Disassembly
Repair & overhaul
From a Cummins/Onan service manual covering: 2.5 MAJB-53BR, 2.5 MAJB-53CR, 3.0 MAJB-1R. Check it applies to your exact model before use.
Applies to: Cummins/Onan MAJ, Cummins/Onan MAJB engine
Before you start
- Disconnect starting battery cables when repairs are made
Procedure
- Remove the belt guard, belt and pulley.
- Remove the 2 capscrews securing the pump to its bracket.
- Remove the pump end plate screws, end plate, and gasket.
- Pull out the neoprene impeller using 2 screwdrivers or pliers.
- Loosen the set screw on the pump body, tap it lightly, and lift out the cam and wear plate.
- Remove the plastic end cap/seal from the pump body (pulley end of shaft).
- Remove the bearing and shaft retaining rings at the pulley end of the pump body.
- Push the shaft and bearing assembly out the pulley end of the pump body.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan MAJ →
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.