Cummins/Onan — Rotor Loosening

For these Cummins/Onan models: 4CFKM, 4CFKM/4CKMR (50 Hz), 4CFKMR, 4CKM, 4CKM/4CFKMR (60 Hz), 4CKMR, 5CKM, 5CKM/SCKMR (60 Hz), 5CKMR, ACFKM/4CFKMR (50 Hz), ACKM/4CKMR (60 Hz).

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Procedure

1. Loosen thrubolt 2-3 turns leaving an 1/8 in. (3 mm) gap between bolt and rotor using a 3/4 in. socket wrench.
2. Use a strap wrench on rotor windings and socket wrench on thrubolt (or place wrench on thrubolt and strike wrench with lead hammer using a medium force blow) to loosen the bolt.

Source: manual:TP5394 Kohler Gen Service 4CKM 5CKM (12-1994).pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.