Cummins/Onan — Cooling System Cleaning and Changing Antifreeze
Maintenance
From a Cummins/Onan owner's manual covering: K1800, K2000E, K38, K50, KT38, KTA38, KTA50, KTTA38, KTTA50, KtA38, KtA50, KttA38. Check it applies to your exact model before use.
Applies to: Cummins/Onan K38, Cummins/Onan K50, Cummins/Onan KTA38, Cummins/Onan KTA50, Cummins/Onan K38 and K50 engine
Before you start
- Do not use caustic cleaners in the cooling system. Aluminum components will be damaged.
- Wait until the temperature is below 50 C [120 F] before removing the coolant system pressure cap.
Procedure
- Drain the cooling system. Do not allow the cooling system to dry out. Do not remove the coolant filter.
- Add 3.8 liters [1 U.S. gallon] of Fleetguard RESTORE (or equivalent) for each 38 to 57 liters [10 to 15 gallons] of cooling system capacity and fill with plain water.
- Turn the heater temperature switch to high to allow maximum coolant flow.
- Operate the engine at normal operating temperatures (at least 85 C [185 F]) for 1 to 1 1/2 hours.
- Shut the engine off and drain the cooling system.
- Fill with clean water to flush and operate at high idle for 5 minutes above 85 C [185 F].
- Shut the engine off and drain. Repeat flushing if the water is still dirty.
- Refill the system with new heavy duty coolant and SCA.
Specs & values
Full service-parts list: Cummins/Onan K38 →, Cummins/Onan K50 →, Cummins/Onan KTA38 →, Cummins/Onan KTA50 →
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.