Cummins/Onan — Replacing Spark Plugs
Maintenance · Ignition
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HGJAA, Cummins/Onan HGJAB, Cummins/Onan HGJAC, Cummins/Onan HGJAD, Cummins/Onan HGJAE, Cummins/Onan HGJAF
Procedure
- Thread spark plug in by hand until it seats.
- Torque to 13 Nm (10 lb-ft) if new.
- Torque to 24 Nm (18 lb-ft) if being reused.
- Check and reset gap to 0.025 inch (0.6 mm).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Spark plug torque 10 lb-ft (13 Nm) new
- Spark plug torque 18 lb-ft (24 Nm) reused
- Gap 0.025 in (0.6 mm)
Full service-parts list: Cummins/Onan HGJAA →, Cummins/Onan HGJAB →, Cummins/Onan HGJAC →, Cummins/Onan HGJAD →
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.