Cummins/Onan 4MCCK / 605MCCK — Cooling System Flush
Maintenance
For the Cummins/Onan 4MCCK / 605MCCK, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 605MCCK, Cummins/Onan MCCK, Cummins/Onan MCCK engine
Procedure
- Remove the thermostats and the water pump cover.
- Partially restrict the pump opening so the cylinder block fills with water.
- Attach the flushing gun nozzle to the thermostat opening and fill the block with water.
- Apply air pressure.
- Repeat the process until water coming from the block is clean.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan 605MCCK →, Cummins/Onan MCCK →
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.