Cummins/Onan — Refilling the Cooling System
Maintenance · Engine Cooling System
From a Cummins/Onan operator's manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDKB, Cummins/Onan MDKBH
Before you start
- Low coolant level can cause severe engine damage. Make sure the system is full.
- Filling a hot engine with cold water can cause cracks in the manifold, head and block.
Procedure
- Close the block drain cap and reconnect the pump inlet hose, then fill the system through the engine fill neck to the bottom of the fill neck.
- Start and run the engine for a couple of minutes to dislodge air pockets, then shut it down.
- Add as much coolant as necessary and secure the pressure cap.
- Refill the recovery tank up to the COLD mark.
Full service-parts list: Cummins/Onan MDKB →, Cummins/Onan MDKBH →
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.