Cummins/Onan 12.5 RDJC / 15.0 RDJC — Returning a Unit to Service
Maintenance · Generator set
For the Cummins/Onan 12.5 RDJC / 15.0 RDJC, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan 12.5 RDJC, Cummins/Onan 15.0 RDJC, Cummins/Onan RDJC
Before you start
- Do not smoke or allow any ignition source while servicing batteries
Procedure
- Remove the cover and all protective wrapping; remove the plug from the intake and exhaust outlet.
- Check the warning tag on the oil base and verify that the oil viscosity is still correct for the existing ambient temperature.
- Clean cooling fin areas.
- Clean and check the battery; measure specific gravity (1.260 at 80°F [27°C]) and verify level is at the split ring.
- Charge until the correct value is obtained; add distilled water if level is low. Do not overcharge.
- Connect the starting battery (ground terminal last).
- Prime the fuel system.
- Remove all loads before starting the engine.
- Start engine and observe oil pressure gauge and charge rate ammeter.
- After start, apply load to at least 50 percent of rated capacity.
Tools required
- Battery hydrometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Specific gravity 1.260 at 80°F (27°C)
Full service-parts list: Cummins/Onan RDJC →
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.