Cummins/Onan — Heat Exchanger Filling
Maintenance · Heat exchanger (optional)
From a Cummins/Onan operator's manual covering: 12.0MDJF-53CR, 12.0MDJF-53CR4, 12.0MDJF-54R, 12.0MDJF-55DR, 12.0MDJF-57R, 15.0MDJ F .. .4R 196 D, 15.0MDJF, 15.0MDJF-3CR, 15.0MDJF-3CR4, 15.0MDJF-5DR. Check it applies to your exact model before use.
Applies to: Cummins/Onan 12.0MDJF-53CR, Cummins/Onan MDJF (Onan J-series diesel) engine, Cummins/Onan MDJF engine
Before you start
- After running 10 minutes the closed cooling system is pressurized and hot; open the 14 lb pressure cap slowly to vent pressure.
Procedure
- Remove fill cap.
- Open fill vent valve (turn counterclockwise).
- Remove vent plug (Spec A through C).
- Fill with coolant.
- Close fill vent valve (turn clockwise).
- Replace vent plug and fill cap.
- Operate unit 10 minutes at full load; watch for leaks.
- Shut down; slowly open the 14 lb pressure cap and check water level; fill to top with coolant.
Specs & values
- 14 lb pressure cap
Full service-parts list: Cummins/Onan 12.0MDJF-53CR →
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.