Cummins/Onan — Filling Cooling System
Maintenance
From a Cummins/Onan operator's manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DGAB, Cummins/Onan DGAC, Cummins/Onan DGAD, Cummins/Onan DGAE, Cummins/Onan 4A2.3 engine, Cummins/Onan 6A3.4 engine, Cummins/Onan 6AT3.4 engine
Before you start
- Do not open radiator or heat exchanger pressure cap while engine is running.
Procedure
- Verify all drain cocks are closed and all hose clamps secure.
- Remove cooling system pressure cap and slowly fill with recommended coolant.
- Limit fill rate to 3 gallons/minute to allow engine block to fill completely.
- When engine first starts, remove pressure cap and monitor coolant level.
- Add coolant as trapped air is expelled; replace pressure cap when level is stable.
Specs & values
- Fill rate limit: 3 gallons/minute
Full service-parts list: Cummins/Onan DGAB →, Cummins/Onan DGAC →, Cummins/Onan DGAD →, Cummins/Onan DGAE →
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.