Cummins/Onan — Filling the Cooling System
Maintenance
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HDKA
Before you start
- Do not open the cap or drain while coolant is hot and pressurized.
Procedure
- Verify all drain cocks are closed and all hose clamps secure.
- Remove the cooling system pressure cap.
- Slowly fill the cooling system with the coolant mixture.
- Add coolant to the recovery tank to the full-cold level.
- Start the engine, remove the pressure cap, and monitor the coolant level.
- Add coolant as trapped air is expelled.
- Replace the pressure cap when the level is stable.
Specs & values
- 50/50 ethylene glycol/water mixture
- Do not exceed 50/50 mixture
Full service-parts list: Cummins/Onan HDKA →
Source: Cummins/Onan service 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.