Cummins/Onan — Bleeding Air from the Cooling System
Maintenance
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Fill radiator with 50-50 mix of ethylene glycol anti-freeze and water.
- Remove plug or sender from water manifold on top of engine to vent trapped air; replace when water emerges.
- Remove plug on top of water pump housing to vent trapped air; replace when water emerges.
- Fill radiator to proper level.
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.