Compatible — Water Pump Assembly - Type M32-0115 Neoprene Impeller

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

Procedure

1. Install the ceramic part of the two piece seal assembly in the pump housing with rubber side toward the bearings
2. Coat the inside of the water pump housing and the outside of the ball bearing races with grease
3. Insert the water pump shaft into the pump housing and install the internal retaining ring in the drive pulley end of the housing
4. Install the spring portion of the two piece seal on the pump shaft and secure in place with the external retaining ring
5. Install the wear plate so that the notch in the plate fits into the machining in the pump housing
6. Coat the inside of the impeller housing with grease
7. Install the impeller in the impeller housing by twisting it clockwise while pushing it into place
8. While holding the gasket in place against the pump housing, install the impeller housing securing it with four screws removed during disassembly
9. Mount the pump on the engine and attach the hoses
10. Align the pump drive pulley with the crankshaft drive pulley and tighten the set screw

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.