Cummins/Onan — Break-in period after new rings or pistons
Maintenance · Engine
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Run the engine for 15 to 20 minutes at no load.
- Run about 1/2 hour at 1/3 load.
- Run 2 to 3 hours at 2/3 load.
- Then resume regular operation.
- Avoid light loads during balance of the break-in period to best seat rings for oil control.
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.