Cummins/Onan CFP5E / CFP7E — Drain and Flush Cooling System
Maintenance
For the Cummins/Onan CFP5E / CFP7E, from the Cummins/Onan owner's manual.
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Before you start
- Do not remove pressure cap from hot engine.
Procedure
- Remove coolant expansion tank pressure/fill cap to vent system.
- Unplug engine heater power supply before draining.
- Place container holding at least 10 gallons under engine heater.
- Disconnect engine heater coolant hose and allow coolant to drain.
- Flush with clean fresh water or heavy-duty heat exchanger cleaner.
- If using soapy water solution, flush again with clear water.
- Reconnect engine heater coolant hose.
- Fill with 50% water and 50% ethylene-glycol or propylene-glycol antifreeze.
Tools required
- container Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 50% mixture protects to -37° C (-34° F)
Source: Cummins/Onan owner'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.