Cummins/Onan — Replacing Raw Water Pump Impeller
Maintenance
From a Cummins/Onan owner's manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDDC, John Deere 4045TFM engine, John Deere 6068TFM engine
Before you start
- Do not lubricate with petroleum products which attack impeller materials.
Procedure
- Close the sea-cock.
- Remove impeller cover and gasket; use removal tool if necessary to pull impeller off shaft.
- Install new impeller, twisting clockwise while squeezing into housing.
- Wet pump interior and impeller with water, soap solution, or silicone lubricant.
- Secure cover using a new gasket.
- If strainer is above water line, fill it for faster prime and secure cover.
- Open sea-cock, reconnect negative battery cables, start generator set.
- If it shuts down (Code 7, no raw water flow within 8 seconds), remove blockage and restart.
Tools required
- Impeller removal tool Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Shutdown within 8 seconds if no raw water flow
Full service-parts list: Cummins/Onan MDDC →, John Deere 4045TFM engine →
Source: Cummins/Onan owner's 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.