Compatible — Water Pump Disassembly - Type 132-0115 Neoprene Impeller

For these models: MDJA, MDJB, MDJC, MDJE, MDJF.

Procedure

1. Remove the pump end plate screws and lock washers, end plate, and gasket
2. Pull out neoprene impeller with a pair of pliers, being careful not to damage the pump body
3. If further disassembly is necessary, disconnect the hoses and remove the two capscrews holding the pump to the engine
4. Lift pump from engine
5. Remove the snap ring from the drive end of the pump shaft
6. Remove the shaft assembly by tapping lightly on the drive end of the shaft using a brass or wood dowel to avoid damaging the shaft
7. Slide the seal and spring assembly off the drive end of the shaft
8. Insert the drive end of the shaft into the impeller end of the pump, guide the shaft through the seal until the shaft shoulders against the bearing
9. Tap lightly on the shaft with a brass or wood dowel until the bearing is out, also remove the oil slinger or O-ring
10. Insert the impeller end of the shaft into the engine end of the pump and guide it through until the snap ring shoulders against the seal seat
11. Tap lightly on the shaft until the seal seat is out
12. The graphite bushing in the end plate may be removed by drilling - do not drill through the end of the cover plate

Source: manual:974-0750_Onan_MDJA_to_MDJF_Marine_Diesel_Engine_Service_Manual_12-1985.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.