Cummins/Onan 1B Series / 1B Series Plant — Piston ring service

Repair & overhaul · engine

For the Cummins/Onan 1B Series / 1B Series Plant, from the Cummins/Onan operator's manual.

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Procedure

1. Aluminum piston has three compression rings and one oil control ring. If doubt about serviceability of old rings, install new ones.
2. Fit each ring individually to cylinder from crankcase end.
3. Correct gap of ring when properly fitted to cylinder is 0.010 to 0.015 of an inch. If ring is not too large, ends may be filed slightly to correct gap clearance.
4. Thoroughly clean carbon from ring grooves so new ring will roll freely in grooves completely around piston.
5. Tapered type rings will be marked 'Top' or identified in some manner; this mark must be placed toward top of piston.
6. Space ring gaps at equal distance 1/4 of the way around piston one gap from the other.

Source: Cummins/Onan operator'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.

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