Cummins/Onan — Draining and Flushing
Maintenance · Cooling system
From a Cummins/Onan operator's manual — check it applies to your exact model before use.
Applies to: Cummins/Onan GGHE, Cummins/Onan GGHF, Cummins/Onan Modified Ford V-10 WSG-1068 engine
Before you start
- Some coolant is toxic; keep away from children and animals; follow local environmental regulations for disposal.
- The heater element will burn out if engine coolant is removed with heater connected to power source.
Procedure
- Disconnect engine coolant heater from power source if equipped.
- Allow engine to cool, then remove radiator pressure cap.
- Open radiator drain cock and remove water drain plugs (one on each side of engine).
- Place end of water hose in radiator filler; regulate flow equal to outflow from drains.
- Continue flushing until outflow is clear of rust sediment.
- Replace water drain plugs and close radiator drain cock.
- Refill cooling system with recommended coolant.
Tools required
- water hose Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan GGHE →, Cummins/Onan GGHF →
Source: Cummins/Onan operator'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.