Cummins/Onan — Piston Ring Fitting
Repair & overhaul · Piston and rings
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Do not use rings which require too much filing.
Procedure
- Check ring gap by placing each ring squarely in its cylinder at the bottom of its travel.
- File slightly oversize rings as necessary to obtain the correct gap.
- Use standard size rings on a .005 inch oversize piston.
- Space each ring gap one third of the way around the piston from the preceding one.
- Fit bottom groove with expander and oil control ring, two upper grooves with compression rings.
- Install the chrome-faced ring in the top groove.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Ring gap per Assembly Torques and Clearances section
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.