Cummins/Onan — Returning the Generator Set to Service
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
- Reconnect negative battery cable last.
Procedure
- Check oil tag and change oil if viscosity is not appropriate for expected temperatures.
- Reconnect starting battery, negative cable last.
- Replace raw water pump impeller if over one year old.
- Service air filter element if dirty.
- Reinstall serpentine belt if equipped (see Service Manual).
- Engage PTO clutch if equipped.
- Perform required maintenance.
- After connecting battery, complete pre-start checks and prime fuel system.
- Start and run the generator set.
- Turn on line circuit breaker or distribution panel when ready to power loads.
Tools required
- Insulated wrench Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Replace raw water pump impeller if over one year old
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.